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Sample records for antiproton beams stopping

  1. Calculated LET Spectrum from Antiproton Beams Stopping in Water

    DEFF Research Database (Denmark)

    Bassler, Niels; Holzscheiter, Michael

    2009-01-01

    significantly differ from unity, which seems to warrant closer inspection of the radiobiology in this region. Monte Carlo simulations using FLUKA were performed for calculating the entire particle spectrum of a beam of 126 MeV antiprotons hitting a water phantom. In the plateau region of the simulated...... antiproton beam we observe a dose-averaged unrestricted LET of about 4 keV/μm, which is very different from the expected 0.6 keV/μm of an equivalent primary proton beam. Even though the fluence of secondaries is a magnitude less than the fluence of primary particles, the increased stopping power...

  2. Calculated LET spectrum from antiproton beams stopping in water

    CERN Document Server

    Bassler, Niels

    2009-01-01

    Antiprotons have been proposed as a potential modality for radiotherapy because the annihilation at the end of range leads to roughly a doubling of physical dose in the Bragg peak region. So far it has been anticipated that the radiobiology of antiproton beams is similar to that of protons in the entry region of the beam, but very different in the annihilation region, due to the expected high-LET components resulting from the annihilation. On closer inspection we find that calculations of dose averaged LET in the entry region may suggest that the RBE of antiprotons in the plateau region could significantly differ from unity, which seems to warrant closer inspection of the radiobiology in this region. Materials and Methods. Monte Carlo simulations using FLUKA were performed for calculating the entire particle spectrum of a beam of 126 MeV antiprotons hitting a water phantom. Results and Discussion. In the plateau region of the simulated antiproton beam we observe a dose-averaged unrestrict...

  3. Measurement of the antiproton stopping power of gold - the Barkas effect

    Science.gov (United States)

    Medenwaldt, R.; Møller, S. P.; Uggerhøj, E.; Worm, T.; Hvelplund, P.; Knudsen, H.; Elsener, K.; Morenzoni, E.

    1991-05-01

    The stopping power of gold has been measured for antiprotons in the energy range 0.2-3 MeV using a novel time-of-flight technique. The antiproton stopping power is found to be less than half the equivalent proton stopping power near the electronic stopping power maximum. In the high-energy limit the two stopping powers merge.

  4. Measurement of the antiproton stopping power of gold - the Barkas effect

    Energy Technology Data Exchange (ETDEWEB)

    Medenwaldt, R.; Moeller, S.P.; Uggerhoej, E.; Worm, T. (Inst. for Synchrotron Radiation, Aarhus Univ. (Denmark)); Hvelplund, P.; Knudsen, H. (Inst. of Physics, Univ. of Aarhus (Denmark)); Elsener, K. (CERN, Geneva (Switzerland)); Morenzoni, E. (Paul Scherrer Inst., Villigen (Switzerland))

    1991-05-06

    The stopping power of gold has been measured for antiprotons in the energy range 0.2-3 MeV using a novel time-of-flight technique. The antiproton stopping power is found to be less than half the equivalent proton stopping power near the electronic stopping power maximum. In the high-energy limit the two stopping powers merge. (orig.).

  5. Antiproton stopping at low energies: confirmation of velocity-proportional stopping power.

    Science.gov (United States)

    Møller, S P; Csete, A; Ichioka, T; Knudsen, H; Uggerhøj, U I; Andersen, H H

    2002-05-13

    The stopping power for antiprotons in various solid targets has been measured in the low-energy range of 1-100 keV. In agreement with most models, in particular free-electron gas models, the stopping power is found to be proportional to the projectile velocity below the stopping-power maximum. Although a stopping power proportional to velocity has also been observed for protons, the interpretation of such measurements is difficult due to the presence of charge exchange processes. Hence, the present measurements constitute the first unambiguous support for a velocity-proportional stopping power due to target excitations by a pointlike projectile.

  6. Antiproton beam polarizer using a dense polarized target

    Energy Technology Data Exchange (ETDEWEB)

    Wojtsekhowski, Bogdan

    2011-05-01

    We describe considerations regarding the spin filtering method for the antiproton beam. The proposed investigation of the double polarization cross section for antiproton to nucleon interaction is outlined. It will use a single path of the antiproton beam through a dense polarized target, e.g. 3He or CH2, followed by a polarimeter.

  7. Beam position pickup for antiprotons to the ISR

    CERN Multimedia

    CERN PhotoLab

    1981-01-01

    The Antiproton Project, launched for proton-antiproton collisions in the SPS (SPS collider), had a side-line for p-pbar collisions in the ISR. A new transfer line, TT6, was constructed to transport antiprotons from the 26 GeV PS to the injection line TT1 of ISR ring 2. Antiprotons were a scarce commodity. For setting up the lines, beam diagnostic devices in the antiproton path had to work reliably and precisely with just a few low-intensity pilot pules: single bunches of about 2x10**9 antiprotons every few hours. Electrostatic pickup electrodes were used to measure beam position. They could be mounted for measurement in the horizontal plane, as in this picture, or at 90 deg, for the vertical plane.

  8. Measurement of the stopping power of silicon for antiprotons between 0. 2 and 3 MeV

    Energy Technology Data Exchange (ETDEWEB)

    Medenwaldt, R.; Moeller, S.P.; Uggerhoej, E.; Worm, T. (Inst. for Synchrotron Radiation, Aarhus Univ. (Denmark)); Hvelplund, P.; Knudsen, H. (Inst. of Physics, Aarhus Univ. (Denmark)); Elsener, K. (CERN, Geneva (Switzerland)); Morenzoni, E. (Paul Scherrer Inst., Villigen (Switzerland))

    1991-05-01

    Our previous measurement of the stopping power of silicon power of silicon for antiprotons has been extended down to 200 keV. The antiproton stopping power is found to be more than 30% lower than that for equivelocity protons at 200 keV. The ''Z{sub 1}{sup 3} contribution'' to the stopping power (the Barkas effect) is deduced by comparing the stopping power for protons and antiprotons. Comparisons to theoretical estimates are made. (orig.).

  9. Measurement of the stopping power of silicon for antiprotons between 0.2 and 3 MeV

    Science.gov (United States)

    Medenwaldt, R.; Møller, S. P.; Uggerhøj, E.; Worm, T.; Hvelplund, P.; Knudsen, H.; Elsener, K.; Morenzoni, E.

    1991-05-01

    Our previous measurement of the stopping power of silicon for antiprotons has been extended down to 200 keV. The antiproton stopping power is found to be more than 30% lower than that for equivelocity protons at 200 keV. The " Z13 contribution" to the stopping power (the Barkas effect) is deduced by comparing the stopping power for protons and antiprotons. Comparisons to theoretical estimates are made.

  10. Measurement of the Z31 contribution to the stopping power using MeV protons and antiprotons: The Barkas effect

    Science.gov (United States)

    Andersen, L. H.; Hvelplund, P.; Knudsen, H.; Möller, S. P.; Pedersen, J. O. P.; Uggerhöj, E.; Elsener, K.; Morenzoni, E.

    1989-04-01

    The stopping power for antiprotons has been measured for the first time. The antiproton stopping power of silicon is found to be 3%-19% lower than for equivelocity protons over the energy range 3.01 to 0.538 MeV. The ``Z31 contribution'' to the stopping power (the Barkas effect) is deduced by comparing the stopping power for protons and antiprotons.

  11. Antiproton-Decelerator (AD)

    CERN Multimedia

    Laurent Guiraud

    1998-01-01

    When the Low-Energy Antiproton Ring (LEAR) was stopped in 1996, because of its costly operation, a cheaper way of continuing low-energy antiproton physics was sought. The Antiproton-Collector (AC), added in 1987 to the Antiproton Accumulator (AA) to provide a tenfold intensity increase, was converted into the Antiproton-Decelerator (AD). Antiprotons from the target at 3.5 GeV/c are decelerated to 100 MeV/c, and fast-ejected to the experiments. Major changes were necessary. Above all, the conversion from a constant-field machine to one with a magnetic cycle, modulating the field by an impressive factor 35. New systems for stochastic and electron cooling had to be added. Beam diagnostics at an intensity of only 2E7 antiprotons was a challenge. In 2000, the AD began delivery of antiprotons to the experiments.

  12. Beam Measurement Systems for the CERN Antiproton Decelerator (AD)

    CERN Document Server

    Angoletta, Maria Elena; Ludwig, M; Marqversen, O; Odier, P; Pedersen, F; Raich, U; Søby, L; Tranquille, G; Spickermann, T

    2001-01-01

    The new, low-energy antiproton physics facility at CERN has been successfully commissioned and has been delivering decelerated antiprotons at 100 MeV/c since July 2000. The AD consists of one ring where the 3.5 GeV/c antiprotons produced from a production target are injected, rf manipulated, stochastically cooled, decelerated (with further stages involving additional stochastic and electron cooling and rf manipulation) and extracted at 100 MeV/c. While proton test beams of sufficient intensity could be used for certain procedures in AD commissioning, this was not possible for setting-up and routine operation. Hence, special diagnostics systems had to be developed to obtain the beam and accelerator characteristics using the weak antiproton beams of a few 10E7 particles at all momenta from 3.5 GeV/c down to 100 MeV/c. These include systems for position measurement, intensity, beam size measurements using transverse aperture limiters and scintillators and Schottky-based tools. This paper gives an overall view of...

  13. Antiproton beam profile measurements using Gas Electron Multipliers

    CERN Document Server

    Pinto, Serge Duarte; Spanggaard, Jens; Tranquille, Gerard

    2011-01-01

    The new beam profile measurement for the Antiproton Decelerator (AD) at CERN is based on a single Gas Electron Multiplier (GEM) with a 2D readout structure. This detector is very light, ~0.4% X_0, as required by the low energy of the antiprotons, 5.3 MeV. This overcomes the problems previously encountered with multi-wire proportional chambers (MWPC) for the same purpose, where beam interactions with the detector severely affect the obtained profiles. A prototype was installed and successfully tested in late 2010, with another five detectors now installed in the ASACUSA and AEgIS beam lines. We will provide a detailed description of the detector and discuss the results obtained. The success of these detectors in the AD makes GEM-based detectors likely candidates for upgrade of the beam profile monitors in all experimental areas at CERN. The various types of MWPC currently in use are aging and becoming increasingly difficult to maintain.

  14. Nuclear Excitations by Antiprotons and Antiprotonic Atoms

    CERN Multimedia

    2002-01-01

    The proposal aims at the investigation of nuclear excitations following the absorption and annihilation of stopped antiprotons in heavier nuclei and at the same time at the study of the properties of antiprotonic atoms. The experimental arrangement will consist of a scintillation counter telescope for the low momentum antiproton beam from LEAR, a beam degrader, a pion multiplicity counter, a monoisotopic target and Ge detectors for radiation and charged particles. The data are stored by an on-line computer.\\\\ \\\\ The Ge detectors register antiprotonic x-rays and nuclear @g-rays which are used to identify the residual nucleus and its excitation and spin state. Coincidences between the two detectors will indicate from which quantum state the antiprotons are absorbed and to which nuclear states the various reactions are leading. The measured pion multiplicity characterizes the annihilation process. Ge&hyphn. and Si-telescopes identify charged particles and determine their energies.\\\\ \\\\ The experiment will gi...

  15. Stopping power of antiprotons in H, H2, and He targets

    DEFF Research Database (Denmark)

    Lühr, Armin Christian; Saenz, Alejandro

    2009-01-01

    The stopping power of antiprotons in atomic and molecular hydrogen as well as helium was calculated in an impact-energy range from 1 keV to 6.4 MeV. In the case of H2 and He the targets were described with a single-active electron model centered on the target. The collision process was treated...... of the corrections to the first-order stopping number, the average energy transferred to the target electrons, and the relative importance of the excitation and the ionization process for the energy loss of the projectile was determined. Finally, the stopping powers of the H, H2, and He targets were directly...

  16. Interaction of antiprotons with Rb atoms and a comparison of antiproton stopping powers of the atoms H, Li, Na, K, and Rb

    DEFF Research Database (Denmark)

    Lühr, Armin Christian; Fischer, Nicolas; Saenz, Alejandro

    2009-01-01

    Ionization and excitation cross sections as well as electron-energy spectra and stopping powers of the alkali metal atoms Li, Na, K, and Rb colliding with antiprotons were calculated using a time-dependent channel-coupling approach. An impact-energy range from 0.25 to 4000 keV was considered....... The target atoms are treated as effective one-electron systems using a model potential. The results are compared with calculated cross sections for antiproton-hydrogen atom collisions....

  17. Time purified/separated antiproton beam at the AGS

    Energy Technology Data Exchange (ETDEWEB)

    Bachman, M.; Barlett, M.L.; Bonner, B.; Borenstein, S.; Bridges, D.; Brown, H.; Buchanan, J.; Clement, J.C.; Daftari, I.; Debbe, R.

    1984-11-15

    A 1 km antiproton beam has been designed for construction at the AGS. The momentum band can be varied between +- 0.3% to +- 1.0%, and the resolution for tagged particles will be deltap/papprox.10/sup -4/ at beam rates as high as 10/sup 6/ p-bar/s. Separation by decay purification will be on the order of 1 p-bar/10(..pi../sup -/+..mu../sup -/). This beam will be used in a detailed investigation of Charmonium including a measurement of the chi widths. We will also search for expected but as yet unseen states, and search for possible I = 1 events which would imply the existence of four quark states. This facility will also lend itself to a wide variety of exciting physics such as the proton form factor including both e/sup +/e/sup -/ and ..gamma gamma.. final states, two-body hadron final states, antinucleus yields, and possibly tagged hadron beams (i.e., ..lambda.., ..gamma.., etc.). When heavy ions become available at the AGS, one can measure various long lived particle yields. Finally, with as many as 10/sup 7/ polarized muons in the beam, one has the possibility to use them for nuclear structure studies.

  18. Time purified/separated antiproton beam at the AGS

    Energy Technology Data Exchange (ETDEWEB)

    Bachman, M.; Barlett, M.L.; Bonner, B.; Borenstein, S.; Bridges, D.; Brown, H.; Buchanan, J.; Clement, J.C.; Daftari, I.; Debbe, R.

    1984-01-01

    A 1 km antiproton beam has been designed for construction at the AGS. The momentum band can be varied between +-0.3% to +-1.0%, and the resolution for tagged particles will be deltap/p approx. 10/sup -4/ at beam rates as high as 10/sup 6/ anti p/s. Separation by decay purification will be on the order of 1 anti p/10(..pi../sup -/+..mu../sup -/). This beam will be used in a detailed investigation of Charmonium including a measurement of the chi widths. We will also search for expected but as yet unseen states, and search for possible I=1 events which would imply the existence of four quark states. This facility will also lend itself to a wide variety of exciting physics such as the proton form factor including both e/sup +/e/sup -/ and ..gamma gamma.. final states, two-body hadron final states, anti-nucleus yields, and possibly tagged hadron beams (i.e., Lambda, E, etc.). When heavy ions become available at the AGS, one can measure various long lived particle yields. Finally, with as many as 10/sup 7/ polarized muons in the beam, one has the possibility to use them for nuclear structure studies.

  19. BEAM STOP DESIGN METHODOLOGY AND DESCRIPTION OF A NEW SNS BEAM STOP

    Energy Technology Data Exchange (ETDEWEB)

    Polsky, Yarom [ORNL; Plum, Michael A [ORNL; Geoghegan, Patrick J [ORNL; Jacobs, Lorelei L [ORNL; Lu, Wei [ORNL; McTeer, Stephen Mark [ORNL

    2010-01-01

    The design of accelerator components such as magnets, accelerator cavities and beam instruments tends to be a fairly standardized and collective effort within the particle accelerator community with well established performance, reliability and, in some cases, even budgetary criteria. Beam stop design, by contrast, has been comparatively subjective historically with much more general goals. This lack of rigor has lead to a variety of facility implementations with limited standardization and minimal consensus on approach to development within the particle accelerator community. At the Spallation Neutron Source (SNS), for example, there are four high power beam stops in use, three of which have significantly different design solutions. This paper describes the design of a new off-momentum beam stop for the SNS. The technical description of the system will be complemented by a discussion of design methodology. This paper presented an overview of the new SNS HEBT off-momentum beam stop and outlined a methodology for beam stop system design. The new beam stop consists of aluminium and steel blocks cooled by a closed-loop forced-air system and is expected to be commissioned this summer. The design methodology outlined in the paper represents a basic description of the process, data, analyses and critical decisions involved in the development of a beam stop system.

  20. Colliding beam physics at Fermilab: interaction regions, beam storage, antiproton cooling, production, and colliding

    Energy Technology Data Exchange (ETDEWEB)

    Walker, J.K. (ed.)

    1977-01-01

    The purpose of the colliding beams experment department at Fermilab was to bring about collisions of the stored beams in the energy doubler/saver and main ring, and construct experimental areas with appropriate detectors. To explore the feasibility of using the main ring as a storage device, several studies were carried out to investigate beam growth, loss, and the backgrounds in detectors at possible intersection regions. This range of developments constituted the major topics at the 1977 Summer Study reported here. Emphasis in part one is on interaction regions, beam storage, antiproton cooling, production, and colliding. 40 papers from this part are included in the data base. (GHT)

  1. Beam Dynamics Studies and Design Optimisation of New Low Energy Antiproton Facilities

    CERN Document Server

    Resta-Lopez, Javier; Welsch, Carsten P

    2016-01-01

    Antiprotons, stored and cooled at low energies in a storage ring or at rest in traps, are highly desirable for the investigation of a large number of basic questions on fundamental interactions. This includes the static structure of antiprotonic atomic systems and the time-dependent quantum dynamics of correlated systems. The Antiproton Decelerator (AD) at CERN is currently the worlds only low energy antiproton factory dedicated to antimatter experiments. New antiproton facilities, such as the Extra Low ENergy Antiproton ring (ELENA) at CERN and the Ultra-low energy Storage Ring (USR) at FLAIR, will open unique possibilities. They will provide cooled, high quality beams of extra-low energy antiprotons at intensities exceeding those achieved presently at the AD by factors of ten to one hundred. These facilities, operating in the energy regime between 100 keV down to 20 keV, face several design and beam dynamics challenges, for example nonlinearities, space charge and scattering effects limiting beam life time....

  2. Simulation of an antiprotons beam applied to the radiotherapy; Simulacao de um feixe de antiprotons aplicado a radioterapia

    Energy Technology Data Exchange (ETDEWEB)

    Prata, Leonardo de Almeida

    2006-07-15

    Results for the interaction of a antiproton beam with constituent nuclei of the organic matter are presented. This method regards of the application of an computational algorithm to determine quantitatively the differential cross sections for the scattered particles, starting from the interaction of these antiprotons with the nuclei, what will allow in the future to draw the isodose curve for antiproton therapy, once these beams are expected to be used in cancer treatment soon. The calculation will be done through the application of the concepts of the method of intranuclear cascade, providing yield and differential cross sections of the scattered particles, present in the software MCMC. Th algorithm was developed based on Monte Carlo's method, already taking into account a validate code. The following physical quantities are presented: the yield of secondary particles, their spectral and angular distributions for these interactions. For the energy range taken into account the more important emitted particles are protons, neutrons and pions. Results shown that emitted secondary particles can modify the isodose curves, because they present high yield and energy for transverse directions. (author)

  3. Non-Gaussian beam dynamics in low energy antiproton storage rings

    Science.gov (United States)

    Resta-López, J.; Hunt, J. R.; Welsch, C. P.

    2016-10-01

    In low energy antiproton facilities, where electron cooling is fundamental, the cooling forces together with heating phenomena causing emittance blow-up, such as Intra Beam Scattering (IBS), result in highly non-Gaussian beam distributions. In these cases, a precise simulation of IBS effects is essential to realistically evaluate the long term beam evolution, taking into account the non-Gaussian characteristics of the beam. Here, we analyse the beam dynamics in the Extra Low ENergy Antiproton ring (ELENA), which is a new small synchrotron currently being constructed at CERN to decelerate antiprotons to energies as low as 100 keV. Simulations are performed using the code BETACOOL, comparing different models of IBS.

  4. A new antiproton beam transfer scheme without coalescing

    Energy Technology Data Exchange (ETDEWEB)

    Weiren Chou et al.

    2003-06-04

    An effective way to increase the luminosity in the Fermilab Tevatron collider program Run2 is to improve the overall antiproton transfer efficiency. During antiproton coalescing in the Main Injector (MI), about 10-15% particles get lost. This loss could be avoided in a new antiproton transfer scheme that removes coalescing from the process. Moreover, this scheme would also eliminate emittance dilution due to coalescing. This scheme uses a 2.5 MHz RF system to transfer antiprotons from the Accumulator to the Main Injector. It is then followed by a bunch rotation in the MI to shorten the bunch length so that it can be captured by a 53 MHz RF bucket. Calculations and ESME simulations show that this scheme works. No new hardware is needed to implement this scheme.

  5. Study of Anti-Hydrogen and Plasma Physics 4.Observation of Antiproton Beams and Nonneutral Plasmas

    CERN Document Server

    Hori, Masaki; Fujiwara, Makoto; Kuroda, Naofumi

    2004-01-01

    Diagnostics of antiproton beams and nonneutral plasmas are described in this chapter. Parallel plate secondary electron emission detectors are used to non-destructively observe the beam position and intensity without loss. Plastic scintillation tracking detectors are useful in determining the position of annihilations of antiprotons in the trap. Three-dimensional imaging of antiprotons in a Penning trap is discussed. The unique capability of antimatter particle imaging has allowed the observation of the spatial distribution of particle loss in a trap. Radial loss is localized to small spots, strongly breaking the azimuthal symmetry expected for an ideal trap. By observing electrostatic eigen-modes of nonneutral plasmas trapped in the Multi-ring electrode trap, the non-destructive measurement of plasma parameters is performed.

  6. Parallel plate chambers for monitoring the profiles of high-intensity pulsed antiproton beams

    CERN Document Server

    Hori, Masaki

    2004-01-01

    Two types of beam profile monitor with thin parallel-plate electrodes have been used in experiments carried out at the Low Energy Antiproton Ring (LEAR) and Antiproton Decelerator (AD) of CERN. The detectors were used to measure non-destructively the spatial profiles, absolute intensities, and time structures of 100-300-ns- long beam pulses containing between 10**7 and 10**9 antiprotons. The first of these monitors was a parallel plate ionization chamber operated at gas pressure P=65 mbar. The other was a secondary electron emission detector, and was operated in the ultra-high vacuum of the AD. Both designs may be useful in medical and commercial applications. The position-sensitive electrodes in these detectors were manufactured by a novel method in which a laser trimmer was used to cut strip patterns on metallized polyester foils.

  7. Collisions of low-energy antiprotons with molecular hydrogen: ionization, excitation and stopping power

    DEFF Research Database (Denmark)

    Lühr, Armin Christian; Saenz, Alejandro

    2009-01-01

    A time-dependent coupled-channel approach was used to calculate ionization, excitation, and energy-loss cross sections as well as energy spectra for antiproton and proton collisions with molecular hydrogen for impact energies 8 < E < 4000 keV....

  8. Secondary emission monitor for keV ion and antiproton beams

    CERN Document Server

    Sosa, Alejandro; Bravin, Enrico; Harasimowciz, Janusz; Welsch, C P

    2013-01-01

    Beam profile monitoring of low intensity keV ion and antiproton beams remains a challenging task. A Sec- ondary electron Emission Monitor (SEM) has been de- signed to measure profiles of beams with intensities below 107 and energies as low as 20 keV. The monitor is based on a two stage microchannel plate (MCP) and a phosphor screen facing a CCD camera. Its modular design allows two different operational setups. In this contribution we present the design of a prototype and discuss results from measurements with antiprotons at the AEgIS experiment at CERN. This is then used for a characterization of the monitor with regard to its possible future use at different facilities.

  9. Report of the Snowmass T4 working group on particle sources: Positron sources, anti-proton sources and secondary beams

    Energy Technology Data Exchange (ETDEWEB)

    N. Mokhov et al.

    2002-12-05

    This report documents the activities of the Snowmass 2001 T4 Particle Sources Working Group. T4 was charged with examining the most challenging aspects of positron sources for linear colliders and antiproton sources for proton-antiproton colliders, and the secondary beams of interest to the physics community that will be available from the next generation of high-energy particle accelerators. The leading issues, limiting technologies, and most important R and D efforts of positron production, antiproton production, and secondary beams are discussed in this paper. A listing of T4 Presentations is included.

  10. Precision measurement of antiprotonic hydrogen and deuterium X-rays

    Science.gov (United States)

    Heitlinger, K.; Bacher, R.; Badertscher, A.; Blüm, P.; Eades, J.; Egger, J.; Elsener, K.; Gotta, D.; Morenzoni, E.; Simons, L. M.

    1992-09-01

    X-rays from antiprotonic hydrogen and deuterium have been measured at low pressures. Using the cyclotron trap, a 105 MeV/c antiproton beam from LEAR was stopped with an efficiency of 86% in 30 mbar hydrogen gas in a volume of only 100 cm3. The X-rays were measured with Si(Li) detectors and a Xe-CH4 drift chamber. The strong interaction shift and broadening of the Lyman α transition and the spin-averaged 2p width in antiprotonic hydrogen was measured with unprecedented accuracy. The triplet component of the ground state in antiprotonic hydrogen was determined for the first time.

  11. Study of X-Ray and $\\gamma$-Ray Spectra from Antiprotonic Atoms at the Slowly Extracted Antiproton Beam of LEAR

    CERN Multimedia

    2002-01-01

    This experiment will study the X-ray spectra of antiprotonic atoms and the $\\gamma$ spectra of residual nuclei after the antiproton absorption. We intend to begin with measurements on selected isotopically pure targets. Strong interaction effects, the antiproton absorption and the atomic cascade are analysed through the measurement of energies, lineshapes, relative and absolute intensities of all observable lines. The experiments are continued to determine st in resolved fine structure levels and in different isotopes of the same element. Coincidence techniques may be applied. All components of the experimental set-up are already existing from previous experiments and we could begin the measurements with any slowly extracted beam of low energy at LEAR.

  12. Physics using cold antiprotons

    Science.gov (United States)

    Hayano, Ryugo S.

    2004-10-01

    Recent progress of low-energy antiproton physics by atomic spectroscopy and collisions using slow antiprotons collaboration at CERN AD is presented. High-precision spectroscopy of antiprotonic helium-a neutral three-body system overlinepe-He2+(=overlinepHe+) produced when antiprotons (overlinep) are stopped in various phases of helium-has tested 3-body QED theories as well as proton-vs-antiproton CPT to within ∼10-8. This was achieved by using a newly-developed radiofrequency quadrupole decelerator. Other ongoing and future experiments using low-energy antiprotons are discussed.

  13. Physics using cold antiprotons

    Energy Technology Data Exchange (ETDEWEB)

    Hayano, R.S. E-mail: hayano@phys.s.u-tokyo.ac.jp

    2004-10-11

    Recent progress of low-energy antiproton physics by atomic spectroscopy and collisions using slow antiprotons collaboration at CERN AD is presented. High-precision spectroscopy of antiprotonic helium--a neutral three-body system pbare{sup -}He{sup 2+}(=pbarHe{sup +}) produced when antiprotons (pbar) are stopped in various phases of helium--has tested 3-body QED theories as well as proton-vs-antiproton CPT to within {approx}10{sup -8}. This was achieved by using a newly-developed radiofrequency quadrupole decelerator. Other ongoing and future experiments using low-energy antiprotons are discussed.

  14. Advanced space propulsion study - antiproton and beamed-power propulsion. Final report, 1 May 1986-30 June 1987

    Energy Technology Data Exchange (ETDEWEB)

    Forward, R.L.

    1987-10-01

    The contract objective was to monitor the research at the forefront of physics and engineering to discover new spacecraft-propulsion concepts. The major topics covered were antiproton-annihilation propulsion, laser thermal propulsion, laser-pushed lightsails, tether transportation systems, solar sails, and metallic hydrogen. Five papers were prepared and are included as appendices. They covered 1) pellet, microwave, and laser-beamed power systems for interstellar transport; 2) a design for a near-relativistic laser-pushed lightsail using near-term laser technology; 3) a survey of laser thermal propulsion, tether transportation systems, antiproton annihilation propulsion, exotic applications of solar sails, and laser-pushed interstellar lightsails; 4) the status of antiproton annihilation propulsion as of 1986, and 5) the prospects for obtaining antimatter ions heavier than antiprotons. Two additional appendices contain the first seven issues of the Mirror Matter Newsletter concerning the science and technology of antimatter, and an annotated bibliography of antiproton science and technology.

  15. Antiproton radiotherapy

    CERN Document Server

    Bassler, Niels; Beyer, Gerd; DeMarco, John J.; Doser, Michael; Hajdukovic, Dragan; Hartley, Oliver; Iwamoto, Keisuke S.; Jakel, Oliver; Knudsen, Helge V.; Kovacevic, Sandra; Møller, Søren Pape; Overgaard, Jens; Petersen, Jørgen B.à; Solberg, Timothy D.; Sørensen, Brita S.; Vranjes, Sanja; Wouters, Bradly G.; Holzscheiter, Michael H.

    2008-01-01

    Antiprotons are interesting as a possible future modality in radiation therapy for the following reasons: When fast antiprotons penetrate matter, protons and antiprotons have near identical stopping powers and exhibit equal radiobiology well before the Bragg-peak. But when the antiprotons come to rest at the Bragg-peak, they annihilate, releasing almost 2 GeV per antiproton–proton annihilation. Most of this energy is carried away by energetic pions, but the Bragg-peak of the antiprotons is still locally augmented with ∼20–30 MeV per antiproton. Apart from the gain in physical dose, an increased relative biological effect also has been observed, which can be explained by the fact that some of the secondary particles from the antiproton annihilation exhibit high-LET properties. Finally, the weakly interacting energetic pions, which are leaving the target volume, may provide a real time feedback on the exact location of the annihilation peak. We have performed dosimetry experiments and investigated the rad...

  16. Antiprotons get biological

    CERN Multimedia

    2003-01-01

    After its final run in September, the first results of the Antiproton Cell Experiment (ACE) look very promising. It was the first experiment to take data on the biological effects of antiproton beams to evaluate the potential of antiprotons in radiation therapy.

  17. antiproton focusing horn

    CERN Multimedia

    1980-01-01

    Was used for the AA (antiproton accumulator). Making an antiproton beam took a lot of time and effort. Firstly, protons were accelerated to an energy of 26 GeV in the PS and ejected onto a metal target. From the spray of emerging particles, a magnetic horn picked out 3.6 GeV antiprotons for injection into the AA through a wide-aperture focusing quadrupole magnet. For a million protons hitting the target, just one antiproton was captured, 'cooled' and accumulated. It took 3 days to make a beam of 3 x 10^11 - three hundred thousand million - antiprotons.

  18. Antiproton Focus Horn

    CERN Multimedia

    1974-01-01

    Was used for the AA (antiproton accumulator). Making an antiproton beam took a lot of time and effort. Firstly, protons were accelerated to an energy of 26 GeV in the PS and ejected onto a metal target. From the spray of emerging particles, a magnetic horn picked out 3.6 GeV antiprotons for injection into the AA through a wide-aperture focusing quadrupole magnet.For a million protons hitting the target, just one antiproton was captured, 'cooled' and accumulated. It took 3 days to make a beam of 3 x 10^11 -, three hundred thousand million - antiprotons.

  19. The CERN antiproton target: hydrocode analysis of its core material dynamic response under proton beam impact

    CERN Document Server

    Martin, Claudio Torregrosa; Calviani, Marco; Muñoz-Cobo, José-Luis

    2016-01-01

    Antiprotons are produced at CERN by colliding a 26 GeV/c proton beam with a fixed target made of a 3 mm diameter, 55 mm length iridium core. The inherent characteristics of antiproton production involve extremely high energy depositions inside the target when impacted by each primary proton beam, making it one of the most dynamically demanding among high energy solid targets in the world, with a rise temperature above 2000 {\\deg}C after each pulse impact and successive dynamic pressure waves of the order of GPa's. An optimized redesign of the current target is foreseen for the next 20 years of operation. As a first step in the design procedure, this numerical study delves into the fundamental phenomena present in the target material core under proton pulse impact and subsequent pressure wave propagation by the use of hydrocodes. Three major phenomena have been identified, (i) the dominance of a high frequency radial wave which produces destructive compressive-to-tensile pressure response (ii) The existence of...

  20. CERN antiproton target: Hydrocode analysis of its core material dynamic response under proton beam impact

    Science.gov (United States)

    Martin, Claudio Torregrosa; Perillo-Marcone, Antonio; Calviani, Marco; Muñoz-Cobo, José-Luis

    2016-07-01

    Antiprotons are produced at CERN by colliding a 26 GeV /c proton beam with a fixed target made of a 3 mm diameter, 55 mm length iridium core. The inherent characteristics of antiproton production involve extremely high energy depositions inside the target when impacted by each primary proton beam, making it one of the most dynamically demanding among high energy solid targets in the world, with a rise temperature above 2000 °C after each pulse impact and successive dynamic pressure waves of the order of GPa's. An optimized redesign of the current target is foreseen for the next 20 years of operation. As a first step in the design procedure, this numerical study delves into the fundamental phenomena present in the target material core under proton pulse impact and subsequent pressure wave propagation by the use of hydrocodes. Three major phenomena have been identified, (i) the dominance of a high frequency radial wave which produces destructive compressive-to-tensile pressure response (ii) The existence of end-of-pulse tensile waves and its relevance on the overall response (iii) A reduction of 44% in tensile pressure could be obtained by the use of a high density tantalum cladding.

  1. Cryogenic Current Comparator as Low Intensity Beam Current Monitor in the CERN Antiproton Decelerators

    CERN Document Server

    Fernandes, M; Soby, L; Welsch, CP

    2013-01-01

    In the low-energy Antiproton Decelerator (AD) and the future Extra Low ENergy Antiproton (ELENA) rings at CERN, an absolute measurement of the beam intensity is essential to monitor any losses during the deceleration and cooling phases. However, existing DC current transformers can hardly reach the μA level, while at the AD and ELENA currents can be as low as 100 nA. A Cryogenic Current Comparator (CCC) based on a superconducting quantum interference device (SQUID) is currently being designed and shall be installed in the AD and ELENA machines. It should meet the following specifications: A current resolution smaller than 10 nA, a dynamic range covering currents between 100 nA and 1 mA, as well as a bandwidth from DC to 1 kHz. Different design options are being considered, including the use of low or high temperature superconductor materials, different CCC shapes and dimensions, different SQUID characteristics, as well as electromagnetic shielding requirements. In this contribution we present first results f...

  2. Thermal excitation of heavy nuclei with 5-15 GeV/c antiproton, proton and pion beams

    CERN Document Server

    Beaulieu, L; Hsi, W C; Lefort, T; Pienkowski, L; Korteling, R G; Wang, G; Back, B B; Bracken, D S; Breuer, H; Cornell, E A; Gimeno-Nogues, F; Ginger, D S; Gushue, S; Huang, M J; Laforest, R; Lynch, W G; Martin, E; Morley, K B; Ramakrishnan, E; Remsberg, L P; Rowland, D; Ruangma, A; Tsang, M B; Viola, V E; Winchester, E M; Xi, H; Yennello, S J

    1999-01-01

    Excitation-energy distributions have been derived from measurements of 5.0-14.6 GeV/c antiproton, proton and pion reactions with $^{197}$Au target nuclei, using the ISiS 4$\\pi$ detector array. The maximum probability for producing high excitation-energy events is found for the antiproton beam relative to other hadrons, $^3$He and $\\bar{p}$ beams from LEAR. For protons and pions, the excitation-energy distributions are nearly independent of hadron type and beam momentum above about 8 GeV/c. The excitation energy enhancement for $\\bar{p}$ beams and the saturation effect are qualitatively consistent with intranuclear cascade code predictions. For all systems studied, maximum cluster sizes are observed for residues with E*/A $\\sim$ 6 MeV.

  3. Physics with thermal antiprotons

    Energy Technology Data Exchange (ETDEWEB)

    Hynes, M.V.; Campbell, L.J.

    1988-01-01

    The same beam cooling techniques that have allowed for high luminosity antiproton experiments at high energy also provide the opportunity for experiments at ultra-low energy. Through a series of deceleration stages, antiprotons collected and cooled at the peak momentum for production can by made available at thermal or sub-thermal energies. In particular, the CERN, PS-200 collaboration is developing an RFO-plused ion trap beam line for the antiproton gravitational mass experiment at LEAR that will provide beams of antiprotons in the energy range 0.001--1000.0 eV. Antiprotons at these energies make these fundamentals particles available for experiments in condensed matter and atomic physics. The recent speculation that antiprotons may form metastable states in some forms of normal matter could open many new avenues of basic and applied research. 7 refs., 3 figs.

  4. LEAR: antiproton extraction lines

    CERN Multimedia

    Photographic Service

    1992-01-01

    Antiprotons, decelerated in LEAR to a momentum of 100 MeV/c (kinetic energy of 5.3 MeV), were delivered to the experiments in an "Ultra-Slow Extraction", dispensing some 1E9 antiprotons over times counted in hours. Beam-splitters and a multitude of beam-lines allowed several users to be supplied simultaneously.

  5. Experimental determination of the complete spin structure for anti-proton + proton -> anti-\\Lambda + \\Lambda at anti-proton beam momentum of 1.637 GeV/c

    CERN Document Server

    Paschke, K D; Berdoz, A; Franklin, G B; Khaustov, P; Meyer, C A; Bradtke, C; Gehring, R; Görtz, S; Harmsen, J; Meier, A; Meyer, W; Radtke, E; Reicherz, G; Dutz, H; Plückthun, M; Schoch, B; Dennert, H; Eyrich, W; Hauffe, J; Metzger, A; Moosburger, M; Stinzing, F; Wirth, S; Fischer, H; Franz, J; Heinsius, F H; Kriegler, E; Schmitt, H; Bunker, B; Hertzog, D; Jones, T; Tayloe, R; Bröders, R; Geyer, R; Kilian, K; Oelert, W; Röhrich, K; Sachs, K; Sefzick, T; Bassalleck, B; Eilerts, S; Fields, D E; Kingsberry, P; Lowe, J; Stotzer, R; Johansson, T; Pomp, S; Wirth, St.

    2006-01-01

    The reaction anti-proton + proton -> anti-\\Lambda + \\Lambda -> anti-proton + \\pi^+ + proton + \\pi^- has been measured with high statistics at anti-proton beam momentum of 1.637 GeV/c. The use of a transversely-polarized frozen-spin target combined with the self-analyzing property of \\Lambda/anti-\\Lambda decay allows access to unprecedented information on the spin structure of the interaction. The most general spin-scattering matrix can be written in terms of eleven real parameters for each bin of scattering angle, each of these parameters is determined with reasonable precision. From these results all conceivable spin-correlations are determined with inherent self-consistency. Good agreement is found with the few previously existing measurements of spin observables in anti-proton + proton -> anti-\\Lambda + \\Lambda near this energy. Existing theoretical models do not give good predictions for those spin-observables that had not been previously measured.

  6. Antiproton Target

    CERN Multimedia

    1980-01-01

    Antiproton target used for the AA (antiproton accumulator). The first type of antiproton production target used from 1980 to 1982 comprised a rod of copper 3mm diameter and 120mm long embedded in a graphite cylinder that was itself pressed into a finned aluminium container. This assembly was air-cooled and it was used in conjunction with the Van der Meer magnetic horn. In 1983 Fermilab provided us with lithium lenses to replace the horn with a view to increasing the antiproton yield by about 30%. These lenses needed a much shorter target made of heavy metal - iridium was chosen for this purpose. The 50 mm iridium rod was housed in an extension to the original finned target container so that it could be brought very close to the entrance to the lithium lens. Picture 1 shows this target assembly and Picture 2 shows it mounted together with the lithium lens. These target containers had a short lifetime due to a combination of beam heating and radiation damage. This led to the design of the water-cooled target in...

  7. Search for polarization effects in the antiproton production process

    CERN Document Server

    Grzonka, D; Ritman, J.; Sefzick, T.; Oelert, W.; Diermaier, M.; Widmann, E.; Zmeskal, J.; Glowacz, B.; Moskal, P.; Zielinski, M.; Wolke, M.; Nadel-Turonski, P.; Carmignotto, M.; Horn, T.; Mkrtchyan, H.; Asaturyan, A.; Mkrtchyan, A.; Tadevosyan, V.; Zhamkochyan, S.; Malbrunot-Ettenauer, S.; Eyrich, W.; Hauenstein, F.; Zink, A.

    2015-01-01

    For the production of a polarized antiproton beam various methods have been suggested including the possibility that antiprotons may be produced polarized which will be checked experimentally. The polarization of antiprotons produced under typical conditions for antiproton beam preparation will be measured at the CERN/PS. If the production process creates some polarization a polarized antiproton beam could be prepared by a rather simple modification of the antiproton beam facility. The detection setup and the expected experimental conditions are described.

  8. Comparison of Optimized Single and Multifield Irradiation Plans of Antiproton, Proton and Carbon Ion Beams

    DEFF Research Database (Denmark)

    Bassler, Niels; Kantemiris, Ioannis; Karaiskos, Pantelis;

    2010-01-01

    Antiprotons have been suggested as a possibly superior modality for radiotherapy, due to the energy released when antiprotons annihilate, which enhances the Bragg peak and introduces a high-LET component to the dose. However, concerns are expressed about the inferior lateral dose distribution...

  9. ASACUSA hits antiproton jackpot

    CERN Multimedia

    2001-01-01

    The Japanese-European ASACUSA collaboration, which takes its name from the oldest district of Tokyo, approaches the antimatter enigma in a different way from the other two AD experiments, by inserting antiprotons into ordinary atoms. Last month the collaboration succeeded in trapping about a million antiprotons. The ASACUSA antiproton trap (lower cylinder), surmounted by its liquid helium reservoir. Looking on are Ken Yoshiki-Franzen, Zhigang Wang, Takahito Tasaki, Suzanne Reed, John Eades, Masaki Hori, Yasunori Yamazaki, Naofumi Kuroda, Jun Sakaguchi, Berti Juhasz, Eberhard Widmann and Ryu Hayano. A key element of the ASACUSA apparatus is its decelerating Radiofrequency Quadrupole magnet, RFQD. After tests with protons in Aarhus, this was installed in ASACUSA's antiproton beam last October (Bulletin 41/2000, 9 October 2000). Constructed by Werner Pirkl's group in PS Division, the RFQD works by applying an electric field to the AD antiproton pulse the opposite direction to its motion. As the antiprotons slo...

  10. Formation spectra of charmed meson--nucleus systems using an antiproton beam

    CERN Document Server

    Yamagata-Sekihara, J; Nieves, J; Salcedo, L L; Tolos, L

    2015-01-01

    We investigate the structure and formation of charmed meson--nucleus systems, with the aim of understanding the charmed meson--nucleon interactions and the properties of the charmed mesons in the nuclear medium. The $\\bar{D}$ mesic nuclei are of special interest, since they have tiny decay widths due to the absence of strong decays for the $\\bar{D} N$ pair. Employing an effective model for the $\\bar{D} N$ and $D N$ interactions and solving the Klein--Gordon equation for $\\bar{D}$ and $D$ in finite nuclei, we find that the $D^{-}$-${}^{11}\\rm{B}$ system has $1 s$ and $2p$ mesic nuclear states and that the $D^{0}$-${}^{11}\\rm{B}$ system binds in a $1s$ state. In view of the forthcoming experiments by the PANDA and CBM Collaborations at the future FAIR facility and the J-PARC upgrade, we calculate the formation spectra of the $[D^{-}$-${}^{11}\\rm{B}]$ and $[D^{0}$-${}^{11}\\rm{B}]$ mesic nuclei for an antiproton beam on a ${}^{12} \\rm{C}$ target. Our results suggest that it is possible to observe the $2 p$ $D^{-}...

  11. Precision measurement of antiprotonic hydrogen and deuterium X-rays

    Energy Technology Data Exchange (ETDEWEB)

    Heitlinger, K.; Bluem, P. (Kernforschungszentrum Karlsruhe GmbH (Germany). Inst. fuer Kernphysik Karlsruhe Univ. (T.H.) (Germany). Inst. fuer Experimentelle Kernphysik); Bacher, R.; Badertscher, A.; Egger, J.; Morenzoni, E.; Simons, L.M. (Paul Scherrer Inst. (PSI), Villigen (Switzerland)); Eades, J.; Elsener, K. (European Organization for Nuclear Research, Geneva (Switzerland)); Gotta, D. (Forschungszentrum Juelich GmbH (Germany). Inst. fuer Kernphysik)

    1992-05-01

    X-rays from antiprotonic hydrogen and deuterium have been measured at low pressures. Using the cylcotron trap, a 105 MeV/c antiproton beam from LEAR was stopped with an efficiency of 86% in 30 mbar hydrogen gas in a volume of only 100 cm{sup 3}. The X-rays were measured with Si(Li) detectors and a Xe-CH{sub 4} drift chamber. The strong interaction shift and broadening of the Lyman {alpha} transition and the spin-averaged 2p width in antiprotonic hydrogen was measured with unprecedented accuracy. The triplet component of the ground state in antiprotonic hydrogen was determined for the first time. (orig.).

  12. Capture, Electron-Cooling and Compression of Antiprotons in a Large Penning-Trap for Physics Experiments with an Ultra-Low Energy Extracted Antiproton Beam

    CERN Multimedia

    2002-01-01

    % PS200 \\\\ \\\\The availability of ultra-low energy antiprotons is a crucial ingredient for the execution of the gravity measurements PS200. We have developed a method to provide such low energy antiprotons based on a large Penning trap (the PS200 catching trap). This system can accept a fast-extracted pulse from LEAR, reduce the energy of the antiprotons in the pulse from 5.9~MeV to several tens of kilovolts using a degrading foil, and then capture the antiprotons in a large Penning trap. These antiprotons are cooled by electrons previously admitted to the trap and are collected in a small region at the center of the trap. We have demonstrated our capability to capture up to 1~million antiprotons from LEAR in a single shot, electron cool these antiprotons, and transfer up to 95\\% of them into the inner, harmonic region. A storage time in excess of 1 hour was observed. These results have been obtained with the cryogenic trap vacuum coupled to a room temperature vacuum at about l0$ ^- ^{1} ^0 $ Torr, which is an...

  13. Depth-Dose and LET Distributions of Antiproton Beams in Various Target Materials

    DEFF Research Database (Denmark)

    Herrmann, Rochus; Olsen, Sune; Petersen, Jørgen B.B.;

    unrestricted LET is calculated for all configurations. Finally, we investigate which concentrations of gadolinium and boron are needed in a water target in order to observe a significant change in the antiproton depth-dose distribution.  Results Results indicate, that there is no significant change...... in the depth-dose distribution and average LET when substituting the materials. Adding boron and gadolinium up to concentrations of 1 per 1000 atoms to a water phantom, did not change the depth-dose profile nor the average LET. Conclusions  According to our FLUKA calculations, antiproton neutron capture...

  14. Experimental setup and first measurement of DNA damage induced along and around an antiproton beam

    DEFF Research Database (Denmark)

    Kavanagh, J. N.; Currell, F. J.; Timson, D. J.;

    2010-01-01

    Radiotherapy employs ionizing radiation to induce lethal DNA lesions in cancer cells while minimizing damage to healthy tissues. Due to their pattern of energy deposition, better therapeutic outcomes can, in theory, be achieved with ions compared to photons. Antiprotons have been proposed to offe...

  15. Antiproton therapy

    CERN Document Server

    Knudsen, Helge V; Bassler, Niels; Alsner, Jan; Beyer, Gerd-Jürgen; DeMarco, John J; Doser, Michael; Hajdukovic, Dragan; Hartley, Oliver; Iwamoto, Keisuke S; Jäkel, Oliver; Kovacevic, Sandra; Møller, Søren Pape; Overgaard, Jens; Petersen, Jørgen B; Ratib, Osman; Solberg, Timothy D; Vranjes, Sanja; Wouters, Bradly G

    2008-01-01

    Radiotherapy is one of the most important means we have for the treatment of localised tumours. It is therefore essential to optimize the technique, and a lot of effort goes into this endeavour. Since the proposal by Wilson in 1946 [R.R. Wilson, Radiology use of fast protons, Radiology 47 (1946) 487.] that proton beams might be better than photon beams at inactivating cancer cells, hadron therapy has been developed in parallel with photon therapy and a substantial knowledge has been gained on the effects of pions, protons and heavy ions (mostly carbon ions). Here we discuss the recent measurements by the CERN ACE collaboration of the biological effects of antiprotons, and argue that these particles very likely are the optimal agents for radiotherapy.

  16. ASACUSA Anti-protonic Helium_Final

    CERN Document Server

    CERN Audiovisual Production Service; CERN AD; Paola Catapano; Julien Ordan, Arzur Catel; Paola Catapano; ASACUSA COLLABORATION

    2016-01-01

    Latest precision measurement of the mass of the proton and the anti proton though the production of antiprotonic helium by the ASACUSA experiment at CERN's antimatter factory, with a beam from the Antiproton Decelerator

  17. Antiproton charge radius

    Science.gov (United States)

    Crivelli, P.; Cooke, D.; Heiss, M. W.

    2016-09-01

    The upcoming operation of the extra low energy antiprotons ring at CERN, the upgrade of the antiproton decelerator (AD), and the installation in the AD hall of an intense slow positron beam with an expected flux of 1 08 e+ /s will open the possibility for new experiments with antihydrogen (H ¯). Here we propose a scheme to measure the Lamb shift of H ¯. For four months of data taking, we anticipate an uncertainty of 100 ppm. This will provide a test of C P T and the first determination of the antiproton charge radius at the level of 10%.

  18. Neutrons from Antiproton Irradiation

    DEFF Research Database (Denmark)

    Bassler, Niels; Holzscheiter, Michael; Petersen, Jørgen B.B.

    Background: Radiotherapy with Antiprotons is currently investigated by the AD-4/ACE collaboration. The hypothesis is that the additional energy released from the antiprotons annihilating at the target nuclei can enable a reduced dose in the entry channel of the primary beam. Furthermore an enhanced...... relative biological effect (RBE) has already been beam measured in spread out Bragg peaks of antiprotons, relative to that found in the plateau region. However, the antiproton annihilation process is associated with a substantial release of secondary particles which contribute to the dose outside...... the neutron spectrum. Additionally, we used a cylindrical polystyrene loaded with several pairs of thermoluminescent detectors containing Lithium-6 and Lithium-7, which effectively detects thermalized neutrons. The obtained results are compared with FLUKA imulations. Results: The results obtained...

  19. GEANT4 simulation of the ACE beam line : Measurement of the energy distribution of degraded Antiproton beam and the ToF signal of generated pions.

    CERN Document Server

    BRAHIMI, Nihel

    2014-01-01

    The present document describes my 8 weeks work project as a summer student at the AEgIS experiment under the supervision of Michael Doser and what i have learned during this period . It can be devided into three main tasks which are: Theoretical preparations concerning low energy antiproton physics. Learning the basic principles of GEANT4 simu- lation toolkit. Using GEANT4 platform to follow up the work of two technical students (Logan and Conrad) in designing an experiment (ACE beam line ) which aims at improving the methods of detect- ing matter-antimatter annihilations vertices at low energies in terms of resolution and accuracy using hybrid detectors .

  20. Measurement of Balmer and Lyman X-rays in antiprotonic hydrogen isotopes at pressures below 300 hPa

    Energy Technology Data Exchange (ETDEWEB)

    Bacher, R.; Bluem, P.; Gotta, D.; Heitlinger, K.; Rohmann, D.; Schneider, M.; Egger, J.; Simons, L.M.; Elsener, K.

    1989-09-01

    X-rays of Balmer and Lyman transitions in antiprotonic hydrogen and of Balmer transitions in antiprotonic deuterium were observed at pressures below 300 hPa using Si(Li) semiconductor detectors. The measurement was performed at the LEAR-facility at a beam momentum of 202 MeV/c. In order to stop antiprotons in a low pressure gaseous target with high efficiency, a novel technique, the cyclotron trap has been used. Absolute yields were determined and compared with cascade calculations. A distinct difference in the cascade of antiprotonic hydrogen and deuterium is found. The parameters of strong interaction in antiprotonic hydrogen are determined to be /epsilon//sub 1s/=-(620+-100) eV, /Gamma//sub 1s/=(1130+-170) eV and /Gamma//sub 2p/=(32+-10) meV. (orig.).

  1. The use of a central beam stop for contrast enhancement in TEM imaging

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Chao [Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ, Delft (Netherlands); College of Computer, National University of Defense Technology, Changsha (China); Xu, Qiang, E-mail: q.xu@tudelft.nl [Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ, Delft (Netherlands); Peters, Peter J. [Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ, Delft (Netherlands); Antoni van Leeuwenhoek Hospital NKI AVL, Netherlands Cancer Institute, Division Cell Biology 2, NL-1066 CX Amsterdam (Netherlands); Zandbergen, Henny [Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ, Delft (Netherlands)

    2013-11-15

    Dark field TEM imaging using a stop of the central beam (DF-000) is reported. It is shown that a strong enhancement in the contrast can be obtained for graphene as example of weak phase object and endocytic multivescilar body as example of an unstained biological sample. No charging or significant contamination of the central beam stop is observed. For graphene, a resolution beyond 1 Å{sup −1} was easily obtained. DF-000 imaging can be considered as a good and easy to use alternative of a phase plate. - Highlights: • Center stop DF imaging is a good method to improve contrast for weak phase object • Charging problem is avoided by using a Mercedes-star-like center stop • C{sub s} correction and CMOS camera improve the center stop DF imaging quality.

  2. Low Energy Antiproton Ring experimental area

    CERN Multimedia

    1991-01-01

    The experimental area at the Low Energy Antiproton Ring (LEAR) is seen. This set up was used to slow down antiprotons which had been produced by colliding a proton beam with a solid target. The experiments in the hall then took antiprotons from LEAR to perform antimatter studies. One such experiment, PS210, produced the world's first antihydrogen atoms.

  3. Stopping intense beams of internally cold molecules via centrifugal forces

    Science.gov (United States)

    Wu, Xing; Gantner, Thomas; Zeppenfeld, Martin; Chervenkov, Sotir; Rempe, Gerhard

    2016-05-01

    Cryogenic buffer-gas cooling produces intense beams of internally cold molecules. It offers a versatile source for studying collision dynamics and reaction pathways in the cold regime, and could open new avenues for controlled chemistry, precision spectroscopy, and exploration of fundamental physics. However, an efficient deceleration of these beams still presents a challenge. Here, we demonstrate that intense and continuous beams of electrically guided molecules produced by a cryogenic buffer-gas cell can be brought to a halt by the centrifugal force in a rotating frame. Various molecules (e.g. CH3F and CF3CCH) are decelerated to below 20m /s at a corresponding output intensity of ~ 6 ×109mm-2 .s-1 . In addition, our RF-resonant depletion detection shows that up to 90 % rotational-state purity can be achieved in the so-produced slow molecular beams.

  4. Electrostatic protocol treatment lens. The purpose of this device is to transport Antiprotons from the new ELENA storage beam to all AD experiments. The electrostatic device was successfully tested in ASACUSA two weeks ago.

    CERN Multimedia

    Maximilien Brice

    2012-01-01

    Electrostatic protocol treatment lens. The purpose of this device is to transport Antiprotons from the new ELENA storage beam to all AD experiments. The electrostatic device was successfully tested in ASACUSA two weeks ago.

  5. Optimal design of a beam stop for Indus-2 using finite element heat transfer studies

    Indian Academy of Sciences (India)

    A K Sinha; K J S Sawhney; R V Nandedkar

    2001-12-01

    This paper describes the design of an in-vacuum, water-cooled beam stop (X-ray shutter) for the materials science (X-ray diffraction) beamline proposed to be built on the wavelength shifter in the Indus-2 (2.5 GeV) synchrotron radiation source. The radiation source impinges ∼ 1 kW power on the beam stop and the heat transfer capabilities of the beam stop have been evaluated. Temperature distribution in the beam stop has been obtained under various cooling conditions using the finite element analysis calculations with ANSYS software. Design parameters of the beam stop have been optimised. It is also shown that radiation cooling alone is not sufficient for taking away the heat load. Water-cooling of the beam stop is essential.

  6. Adjustable hollow-cone output x-ray beam from an ellipsoidal monocapillary with a pinhole and a beam stop.

    Science.gov (United States)

    Sun, Xue-Peng; Liu, Zhi-Gou; Yi, Long-Tao; Sun, Wei-Yun; Li, Fang-Zou; Jiang, Bo-Wen; Ma, Yong-Zhong; Sun, Tian-Xi

    2015-12-10

    A combined shading system (CSS) consisting of a beam stop and a pinhole is proposed to be used between an ellipsoidal monocapillary (EM) and a conventional laboratory x-ray source to obtain an adjustable hollow-cone output beam for different experiments with no need for changing the EM. The CSS can change the incident x-ray beam on the EM by adjusting the position of the beam stop and the pinhole, with the corresponding change of the output beam of the EM. In this study, the adjustable hollow-cone output x-ray beam of an 80-mm-long EM with a CSS was studied in detail with a laboratory Cu x-ray generator with a focal spot diameter of 50 μm. The adjustable range of the focal spot size of the EM was from 8.6 to 58.7 μm. The adjustable range of the gain of the focal spot of the EM was from 0 to 1350. The beam divergence of the hollow-cone output beam of the EM ranged from 6 to 16.75 mrad. The illumination angle of the hollow-cone output beam of the EM ranged from 0 to 5.95 mrad. In addition, the potential application of the proposed adjusting method in testing the performance of the EM is briefly discussed.

  7. Beam characteristics and stopping-power ratios of small radiosurgery photon beams.

    Science.gov (United States)

    Ding, George X; Ding, Frances

    2012-09-07

    Small megavoltage (MV) photon fields of dimensions less than 3 × 3 cm(2) are increasingly being used in modern radiation therapy. To our knowledge, small beam characteristics and dosimetric parameters, such as the energy spectra, particle fluence, and water-to-air stopping-power ratios (SPRs) directly affect the accuracy of small field dosimetry. This study presents the characteristics of small photon beams and investigates the variations of energy spectra of photons and electrons as a function of field size and their effects on the water-to-air SPRs for field sizes ranging from a small 4 mm diameter circular field to a 10 × 10 cm(2) field. It sheds light on the differences between small fields collimated by the cone accessory and X- and Y-jaws and on beam characteristics outside the primary radiation fields. In addition, we also investigated the use of an 'intermediate machine-specific-reference field' (Alfonso et al 2008 Med. Phys. 35 5179-86) to determine if the variations between a small and a reference field can be eased by introducing an intermediate 4 × 4 cm(2) field instead of a standard 10 × 10 cm(2) reference field. The Monte Carlo simulation codes BEAMnrc, DOSXYZnrc and SPRRZnrc were used in this study. The accelerator head and circular cone accessory were simulated in detail including two designs of flattening filters: one for a standard-dose rate (100-600 MU min(-1)) and the other for a high-dose rate (1000 MU min(-1)) 6 MV beam. The mean energy of photons at depths (1.5-30 cm) in water are 1.72-2.36 MeV, 1.55-1.97 MeV, and 1.44-1.74 MeV for field sizes of 4 mm diameter, 4 × 4 cm(2), and 10 × 10 cm(2), respectively. The mean energy also varies significantly for electrons at depths (1.5-30 cm): 0.99-1.25 MeV, 0.94-1.09 MeV, and 0.93-1.04 MeV for field sizes of 4 mm, 4 × 4 cm(2), and 10 × 10 cm(2), respectively. The calculated water-to-air SPRs at depths (1.5-30 cm) are 1.120-1.113, 1.121-1.117, and 1.122-1.119 for field sizes of 4 mm, 4 × 4 cm

  8. Improved calibration of mass stopping power in low density tissue for a proton pencil beam algorithm.

    Science.gov (United States)

    Warren, Daniel R; Partridge, Mike; Hill, Mark A; Peach, Ken

    2015-06-07

    Dose distributions for proton therapy treatments are almost exclusively calculated using pencil beam algorithms. An essential input to these algorithms is the patient model, derived from x-ray computed tomography (CT), which is used to estimate proton stopping power along the pencil beam paths. This study highlights a potential inaccuracy in the mapping between mass density and proton stopping power used by a clinical pencil beam algorithm in materials less dense than water. It proposes an alternative physically-motivated function (the mass average, or MA, formula) for use in this region. Comparisons are made between dose-depth curves calculated by the pencil beam method and those calculated by the Monte Carlo particle transport code MCNPX in a one-dimensional lung model. Proton range differences of up to 3% are observed between the methods, reduced to  stopping power calculation methodology results in relatively minor differences in dose when plans use three fields, but differences are observed at the 2%-2 mm level when a single field uniform dose technique is adopted. It is therefore suggested that the MA formula is adopted by users of the pencil beam algorithm for optimal dose calculation in lung, and that a similar approach is considered when beams traverse other low density regions such as the paranasal sinuses and mastoid process.

  9. Antiprotonic helium

    CERN Multimedia

    Eades, John

    2005-01-01

    An exotic atom in w hich an electron and an antiproton orbit a helium nucleus could reveal if there are any differences between matter and antimatter. The author describes this unusual mirror on the antiworld (5 pages)

  10. Calculated LET-Spectrum of Antiprotons

    DEFF Research Database (Denmark)

    Bassler, Niels

    Introduction Antiprotons as a new beam modality in radiotherapy are being investigated by the AD-4/ACE collaboration since 2002. A beam of antiprotons hitting a water phantom exhibit a similar depth-dose curve as that known from protons, except that the Bragg-peak is significantly pronounced due...

  11. Improved calibration of mass stopping power in low density tissue for a proton pencil beam algorithm

    Science.gov (United States)

    Warren, Daniel R.; Partridge, Mike; Hill, Mark A.; Peach, Ken

    2015-06-01

    Dose distributions for proton therapy treatments are almost exclusively calculated using pencil beam algorithms. An essential input to these algorithms is the patient model, derived from x-ray computed tomography (CT), which is used to estimate proton stopping power along the pencil beam paths. This study highlights a potential inaccuracy in the mapping between mass density and proton stopping power used by a clinical pencil beam algorithm in materials less dense than water. It proposes an alternative physically-motivated function (the mass average, or MA, formula) for use in this region. Comparisons are made between dose-depth curves calculated by the pencil beam method and those calculated by the Monte Carlo particle transport code MCNPX in a one-dimensional lung model. Proton range differences of up to 3% are observed between the methods, reduced to  calculation methodology results in relatively minor differences in dose when plans use three fields, but differences are observed at the 2%-2 mm level when a single field uniform dose technique is adopted. It is therefore suggested that the MA formula is adopted by users of the pencil beam algorithm for optimal dose calculation in lung, and that a similar approach is considered when beams traverse other low density regions such as the paranasal sinuses and mastoid process.

  12. Improved Scatter Correction in X-Ray Cone Beam CT with Moving Beam Stop Array Using Johns' Equation

    CERN Document Server

    Yan, Hao; Tang, Shaojie; Xu, Qiong

    2014-01-01

    In this paper, an improved scatter correction with moving beam stop array (BSA) for x-ray cone beam (CB) CT is proposed. Firstly, correlation between neighboring CB views is deduced based on John's Equation. Then, correlation-based algorithm is presented to complement the incomplete views by using the redundancy (over-determined information) in CB projections. Finally, combining the algorithm with scatter correction method using moving BSA, where part of primary radiation is blocked and incomplete projections are acquired, an improved correction method is proposed. Effectiveness and robustness is validated by Monte Carlo (MC) simulation with EGSnrc on humanoid phantom.

  13. X-rays from antiprotonic3He and4He

    Science.gov (United States)

    Schneider, M.; Bacher, R.; Blüm, P.; Gotta, D.; Heitlinger, K.; Kunold, W.; Rohmann, D.; Egger, J.; Simons, L. M.; Elsener, K.

    1991-06-01

    Antiprotonic X-rays from the helium isotopes have been observed at pressures of 36, 72, 375 and 600 mbar. The antiproton beam from LEAR with momenta of 309 and 202 MeV/c has been stopped at these pressures using the cyclotron trap. The X-rays were detected with Si (Li) and intrinsic Ge semiconductor detectors. Absolute X-ray yields were determined and the strong-interaction 2p shifts and the 2p and 3d broadenings measured to be ɛ2p=(-17±4) eV, Γ2p=(25±9) eV and Γ3d=(2.14 ±0.18) meV for ¯p3He and ɛ2p=(-18±2) eV, Γ2p =(45±5) eV and Γ3d=(2.36±0.10) meV for ¯p4He.

  14. Preliminary shielding analysis in support of the CSNS target station shutter neutron beam stop design%Preliminary shielding analysis in support of the CSNS target station shutter neutron beam stop design

    Institute of Scientific and Technical Information of China (English)

    张斌; 陈义学; 王伟金; 杨寿海; 吴军; 殷雯; 梁天骄; 贾学军

    2011-01-01

    The construction of China Spallation Neutron Source (CSNS) has been initiated in Dongguan, Guangdong, China. Thus a detailed radiation transport analysis of the shutter neutron beam stop is of vital importance. The analyses are performed using the coupled

  15. The antiproton depth–dose curve in water

    CERN Document Server

    Bassler, N; Jäkel, O; Knudsen, H V; Kovacevic, S

    2008-01-01

    We have measured the depth–dose curve of 126 MeV antiprotons in a water phantom using ionization chambers. Since the antiproton beam provided by CERN has a pulsed structure and possibly carries a high-LET component from the antiproton annihilation, it is necessary to correct the acquired charge for ion recombination effects. The results are compared with Monte Carlo calculations and were found to be in good agreement. Based on this agreement we calculate the antiproton depth–dose curve for antiprotons and compare it with that for protons and find a doubling of the physical dose in the peak region for antiprotons.

  16. The Antiproton Accumulator becomes Antiproton Decelerator

    CERN Multimedia

    1980-01-01

    The photos show the Antiproton Accumulator (AA) transformed into Antiproton Decelerator. The AA was used at CERN between 1981 and 1999 before being replaced by the Antiproton Decelerator (AD). The AA was used to collect and stochastically cool antiprotons used in proton-antiproton collisions in the SPS collider. This lead to the discovery of the W and Z bosons in 1983 and the Nobel Prize for Carlo Rubbia and Simon van der Meer in 1984.

  17. The Antiproton Depth-Dose Curve in Water

    DEFF Research Database (Denmark)

    Bassler, Niels; Holzscheiter, Michael; Jäkel, Oliver

    2008-01-01

    We have measured the depth-dose curve of 126 MeV antiprotons in a water phantom using ionization chambers. Since the antiproton beam provided by CERN has a pulsed structure and possibly carries a high-LET component from the antiproton annihilation, it is necessary to correct the acquired charge...

  18. Antiproton radiation found effective in cancer research

    CERN Multimedia

    2003-01-01

    "An international collaboration of scientists has completed the first ever antiproton beam experiments designed to reveal the biological effectiveness of antiproton radiation in terminating cells used for cancer research...PBar Labs assembled the collaboration at CERN (European Organization for Nuclear Research in Geneva) to perform the measurements" (1 page).

  19. Status Report on the Antiproton Decelerator (AD)

    CERN Document Server

    Erikson, T; Möhl, D

    2001-01-01

    CERN's new Antiproton Decelerator (AD) has been delivering a 100 MeV/c antiproton beam to three experiments (ASACUSA, AHENA and ATRAP) since July 10th, 2000. In this status report, we summarise the initial performance of the AD, draw provisional conclusions from the first month of operation and finally give some prospects for the future.

  20. Extra Low ENergy Antiproton

    CERN Multimedia

    To produce dense antiproton beams at very low energies (110 keV), it has been proposed to install a small decelerator ring between the existing AD ring and the experimental area. Phase-space blowup during deceleration is compensated by electron cooling such that the final emittances are comparable to the 5MeV beam presently delivered by the AD. An immediate consequence is a significant increase in the number of trapped antiprotons at the experiments as outlined in the proposal CERN/SPSC-2009-026; SPCS-P-338. This report describes the machine parameters and layout of the proposal ELENA (Extra Low ENergy Antiproton)ring also gives an approximate estimate of cost and manpower needs. Since the initial estimate, published in 2007 (CERN-AB-2007-079), the ELENA design has evolved considerably. This is due to a new location in the AD hall to acommodate for the possibility of another experimental zone, as suggested by the SPCS, and also due to improvements in the ring optics and layout. The cost estimate that is prese...

  1. Annihilation of Antiprotons in Light Nuclei

    Institute of Scientific and Technical Information of China (English)

    M. A. Rana; E. U. Khan; M. I. Shahzad; I. E. Qureshi; F. Malik; G. Sher; S. Manzoor; H. A. Khan

    2006-01-01

    @@ CR-39 detectors have been exposed to a 5.9-MeV antiproton beam using the low energy antiproton ring (LEAR) facility at CERN. At this energy, tracks of antiprotons appear in a CR-39 detector after 135 min of etching in 6 M NaOH at 70℃ . Fluence of the antiproton beam has been determined using track density. We have also found tracks in the etched CR-39 detector at different depths (250-500μm). These tracks have resulted from the annihilation of antiprotons with the constituents (H, C and O) of the CR-39 detector. The goal of the experiment is to develop a simple and low-cost method to study properties of antiparticles and those formed after annihilation of these particles with the target matter.

  2. Preliminary shielding analysis in support of the CSNS target station shutter neutron beam stop design

    Institute of Scientific and Technical Information of China (English)

    ZHANG Bin; CHEN Yi-Xue; WANG Wei-Jin; YANG Shou-Hai; WU Jun; YIN Wen; LIANG Tian-Jiao; JIA Xue-Jun

    2011-01-01

    The construction of China Spallation Neutron Source (CSNS) has been initiated in Dongguan,Guangdong, China.Thus a detailed radiation transport analysis of the shutter neutron beam stop is of vital importance. The analyses are performed using the coupled Monte Carlo and multi-dimensional discrete ordinates method. The target of calculations is to optimize the neutron beamline shielding design to guarantee personal safety and minimize cost. Successful elimination of the primary ray effects via the two-dimensional uncollided flux and the first collision source methodology is also illustrated. Two-dimensional dose distribution is calculated. The dose at the end of the neutron beam line is less than 2.5μSv/h. The models have ensured that the doses received by the hall staff members are below the standard limit required.

  3. Inclusive production of protons, anti-protons, neutrons, deuterons and tritons in p+C collisions at 158 GeV/c beam momentum

    Energy Technology Data Exchange (ETDEWEB)

    Baatar, B.; Kolesnikov, V.; Malakhov, A.; Melkumov, G. [Joint Institute for Nuclear Research, Dubna (Russian Federation); Barr, G.; Tinti, G. [Oxford University, Oxford (United Kingdom); Bartke, J.; Kowalski, M.; Rybicki, A. [Polish Academy of Sciences, H. Niewodniczanski Institute of Nuclear Physics, Cracow (Poland); Betev, L.; Fischer, H.G.; Karev, A.; Wenig, S. [CERN, Geneva (Switzerland); Chvala, O.; Dolejsi, J. [Charles University, Faculty of Mathematics and Physics, Institute of Particle and Nuclear Physics, Prague (Czech Republic); Eckardt, V.; Schmitz, N.; Seyboth, P. [Max-Planck-Institut fuer Physik, Munich (Germany); Fodor, Z.; Vesztergombi, G. [KFKI Research Institute for Particle and Nuclear Physics, Budapest (Hungary); Makariev, M. [Bulgarian Academy of Sciences, Institute for Nuclear Research and Nuclear Energy, Sofia (Bulgaria); Mateev, M. [Sofia University St. Kliment Ohridski, Atomic Physics Department, Sofia (Bulgaria); Stock, R. [Fachbereich Physik der Universitaet, Frankfurt (Germany); Varga, D. [Eoetvoes Lorand University, Budapest (Hungary)

    2013-04-15

    The production of protons, anti-protons, neutrons, deuterons and tritons in minimum bias p+C interactions is studied using a sample of 385 734 inelastic events obtained with the NA49 detector at the CERN SPS at 158 GeV/c beam momentum. The data cover a phase space area ranging from 0 to 1.9 GeV/c in transverse momentum and in Feynman x from -0.8 to 0.95 for protons, from -0.2 to 0.3 for anti-protons and from 0.1 to 0.95 for neutrons. Existing data in the far backward hemisphere are used to extend the coverage for protons and light nuclear fragments into the region of intra-nuclear cascading. The use of corresponding data sets obtained in hadron-proton collisions with the same detector allows for the detailed analysis and model-independent separation of the three principle components of hadronization in p+C interactions, namely projectile fragmentation, target fragmentation of participant nucleons and intra-nuclear cascading. (orig.)

  4. AA antiproton production target

    CERN Multimedia

    1979-01-01

    The first version of the antiproton production target was a tungsten rod, 11 cm long (actually a row of 11 rods, each 1 cm long) and 3 mm in diameter. The rod was embedded in graphite, pressure-seated into an outer casing made of stainless steel. The casing had fins for forced-air cooling. In this picture, the 26 GeV high-intensity beam from the PS enters from the right, where a scintillator screen, with circles every 5 mm in radius, permits precise aim at the target centre. See also 7903034 and 7905094.

  5. AA antiproton production target

    CERN Multimedia

    1979-01-01

    The first version of the antiproton production target was a tungsten rod, 11 cm long and 3 mm in diameter. The rod was embedded in graphite, pressure-seated into an outer casing of stainless steel. At the entrance to the target assembly was a scintillator screen, imprinted with circles every 5 mm in radius, which allowed to precisely aim the 26 GeV high-intensity proton beam from the PS onto the centre of the target rod. The scintillator screen was a 1 mm thick plate of Cr-doped alumina. See also 7903034 and 7905091.

  6. Dose calculations using MARS for Bremsstrahlung beam stops and collimators in APS beamline stations.

    Energy Technology Data Exchange (ETDEWEB)

    Dooling, J.; Accelerator Systems Division (APS)

    2010-11-01

    -dominated regions; for thicker targets, however, the dose-rate no longer depends only on photon attenuation, as photoneutrons (PNs) begin to dominate. The GB radiation-induced photoneutron measurements from four different metals (Fe, Cu, W, and Pb) are compared with MARS predictions. The simulated dose-rates for beamline 6-ID are approximately 3-5 times larger than the measured values, whereas those for beamline 11-ID are much closer. Given the uncertainty in local values of pressure and Z, the degree of agreement between MARS and the PN measurements is good. MARS simulations of GB-induced radiation in and around the FOE show the importance of using actual pressure and gas composition (Z{sub eff}) to obtain accurate PN dose. For a beam current of 300 mA, extrapolating pressure data measured in previously published studies predicts an average background gas pressure of 27 nTorr. An average atomic number of Z{sub eff} = 4.0 is obtained from the same studies. In addition, models of copper masks presently in use at the APS are included. Simulations show that inclusion of exit masks make significant differences in both the radiation spatial distribution within the FOE, as well as the peak intensity. Two studies have been conducted with MARS to assess shielding requirements. First, dose levels in contact with the outside wall of the FOE are examined when GB radiation strikes Pb or W beam stops of varying transverse size within the FOE. Four separate phantom regions are utilized to measure the dose, two at beam elevation and two at the horizontal beam position. The first two phantoms are used for scoring FOE dose along the outside and back walls, horizontally; the second two collect dose on the roof and vertically on the back wall. In all cases, the beam stop depth is maintained at 30 cm. Inclusion of front end (FE) exit masks typically cause a 1-2 order-of-magnitude increase in the dose-rates relative to the case with no masks. Masks place secondary bremsstrahlung sources inside the FOE

  7. Testing Quantum Chromodynamics with Antiprotons

    CERN Document Server

    Brodsky, S J

    2004-01-01

    The antiproton storage ring HESR to be constructed at GSI will open up a new range of perturbative and nonperturbative tests of QCD in exclusive and inclusive reactions. I discuss 21 tests of QCD using antiproton beams which can illuminate novel features of QCD. The proposed experiments include the formation of exotic hadrons, measurements of timelike generalized parton distributions, the production of charm at threshold, transversity measurements in Drell-Yan reactions, and searches for single-spin asymmetries. The interactions of antiprotons in nuclear targets will allow tests of exotic nuclear phenomena such as color transparency, hidden color, reduced nuclear amplitudes, and the non-universality of nuclear antishadowing. The AdS/CFT correspondence of large $N_C$ supergravity theory in higher-dimensional anti-de Sitter space with supersymmetric QCD in 4-dimensional space-time has important implications for hadron phenomenology in the conformal limit, including the nonperturbative derivation of counting rul...

  8. Conceptual Design of an Antiproton Generation and Storage Facility

    Energy Technology Data Exchange (ETDEWEB)

    Peggs, Stephen

    2006-10-24

    The Antiproton Generation and Storage Facility (AGSF) creates copious quantities of antiprotons, for bottling and transportation to remote cancer therapy centers. The first step in the generation and storage process is to accelerate an intense proton beam down the Main Linac for injection into the Main Ring, which is a Rapid Cycling Synchrotron that accelerates the protons to high energy. The beam is then extracted from the ring into a transfer line and into a Proton Target. Immediately downstream of the target is an Antiproton Collector that captures some of the antiprotons and focuses them into a beam that is transported sequentially into two antiproton rings. The Precooler ring rapidly manipulates antiproton bunches from short and broad (in momentum) to long and thin. It then performs some preliminary beam cooling, in the fraction of a second before the next proton bunch is extracted from the Main Ring. Pre-cooled antiprotons are passed on to the Accumulator ring before the next antiprotons arrive from the target. The Accumulator ring cools the antiprotons, compressing them into a dense state that is convenient for mass storage over many hours. Occasionally the Accumulator ring decelerates a large number of antiprotons, injecting them into a Deceleration Linac that passes them into a waiting Penning trap.

  9. Serach for polarization effects in the antiproton production process

    CERN Multimedia

    It is proposed to study polarization effects in the production of antiprotons at the PS test beam line T11 at 3.5 GeV/c momentum. A polarization in the production process has never been studied but if existing it would allow for a rather simple and cheap way to generate a polarized antiproton beam with the existing facilities at CERN.

  10. Control of stopping position of radioactive ion beam in superfluid helium for laser spectroscopy experiments

    Energy Technology Data Exchange (ETDEWEB)

    Yang, X.F., E-mail: yangxf@ribf.riken.jp [School of Physics, Peking University, Chengfu Road, Haidian District, Beijing 100871 (China); RIKEN Nishina Center, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Furukawa, T. [Dept. of Physics, Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachioji, Tokyo 192-0397 (Japan); Wakui, T. [Cyclotron and Radioisotope Center Tohoku University, 6-3 Aoba, Aramaki, Aoba-ku, Sendai, Miyagi 980-8578 (Japan); Imamura, K. [Dept. of Physics, Meiji University, 1-1-1 Higashi-Mita, Tama-ku, Kawasaki, Kanagawa 214-8571 (Japan); Tetsuka, H. [Dept. of Physics, Tokyo Gakugei University, 4-1-1 Nukuikitamachi, Koganei, Tokyo 184-8501 (Japan); Fujita, T. [Dept. of Physics, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043 (Japan); Yamaguchi, Y. [Dept. of Physics, Meiji University, 1-1-1 Higashi-Mita, Tama-ku, Kawasaki, Kanagawa 214-8571 (Japan); Tsutsui, Y. [Dept. of Physics, Tokyo Gakugei University, 4-1-1 Nukuikitamachi, Koganei, Tokyo 184-8501 (Japan); Mitsuya, Y. [Dept. of Physics, Meiji University, 1-1-1 Higashi-Mita, Tama-ku, Kawasaki, Kanagawa 214-8571 (Japan); Ichikawa, Y. [Dept. of Physics, Tokyo Institute of Technology, 2-12-1 O-Okayama, Meguro, Tokyo152-8551 (Japan); Ishibashi, Y. [RIKEN Nishina Center, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Dept. of Physics, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8571 (Japan); Yoshida, N.; Shirai, H. [Dept. of Physics, Tokyo Institute of Technology, 2-12-1 O-Okayama, Meguro, Tokyo152-8551 (Japan); Ebara, Y.; Hayasaka, M. [Dept. of Physics, Tokyo Gakugei University, 4-1-1 Nukuikitamachi, Koganei, Tokyo 184-8501 (Japan); Arai, S.; Muramoto, S. [Dept. of Physics, Meiji University, 1-1-1 Higashi-Mita, Tama-ku, Kawasaki, Kanagawa 214-8571 (Japan); Hatakeyama, A. [Dept. of Applied Physics, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo 184-8588 (Japan); Wada, M.; Sonoda, T. [RIKEN Nishina Center, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); and others

    2013-12-15

    In order to investigate the structure of exotic nuclei with extremely low yields by measuring nuclear spins and moments, a new laser spectroscopy technique – “OROCHI” (Optical Radioisotopes Observation in Condensed Helium as Ion-catcher) has been proposed in recent years. The feasibility of this technique has been demonstrated by means of a considerable amount of offline and online studies of various atoms in superfluid helium. For in-situ laser spectroscopy of atoms in He II, trapping atoms in the observation region of laser is a key step. Therefore, a method which enables us to trap accelerated atoms at a precise position in He II is highly needed for performing experiment. In this work, a technique making use of a degrader, two plastic scintillators and a photon detection system is established for checking the stopping position of beam based on the LISE++ calculation. The method has been tested and verified by on-line experiments with the {sup 84,85,87}Rb beam. Details of the experimental setup, working procedure and testing results of this method are presented.

  11. Beam-energy dependence of the directed flow of protons, antiprotons, and pions in Au+Au collisions.

    Science.gov (United States)

    Adamczyk, L; Adkins, J K; Agakishiev, G; Aggarwal, M M; Ahammed, Z; Alekseev, I; Alford, J; Anson, C D; Aparin, A; Arkhipkin, D; Aschenauer, E C; Averichev, G S; Banerjee, A; Beavis, D R; Bellwied, R; Bhasin, A; Bhati, A K; Bhattarai, P; Bichsel, H; Bielcik, J; Bielcikova, J; Bland, L C; Bordyuzhin, I G; Borowski, W; Bouchet, J; Brandin, A V; Brovko, S G; Bültmann, S; Bunzarov, I; Burton, T P; Butterworth, J; Caines, H; Calderón de la Barca Sánchez, M; Cebra, D; Cendejas, R; Cervantes, M C; Chaloupka, P; Chang, Z; Chattopadhyay, S; Chen, H F; Chen, J H; Chen, L; Cheng, J; Cherney, M; Chikanian, A; Christie, W; Chwastowski, J; Codrington, M J M; Contin, G; Cramer, J G; Crawford, H J; Cui, X; Das, S; Davila Leyva, A; De Silva, L C; Debbe, R R; Dedovich, T G; Deng, J; Derevschikov, A A; Derradi de Souza, R; Dhamija, S; di Ruzza, B; Didenko, L; Dilks, C; Ding, F; Djawotho, P; Dong, X; Drachenberg, J L; Draper, J E; Du, C M; Dunkelberger, L E; Dunlop, J C; Efimov, L G; Engelage, J; Engle, K S; Eppley, G; Eun, L; Evdokimov, O; Eyser, O; Fatemi, R; Fazio, S; Fedorisin, J; Filip, P; Finch, E; Fisyak, Y; Flores, C E; Gagliardi, C A; Gangadharan, D R; Garand, D; Geurts, F; Gibson, A; Girard, M; Gliske, S; Greiner, L; Grosnick, D; Gunarathne, D S; Guo, Y; Gupta, A; Gupta, S; Guryn, W; Haag, B; Hamed, A; Han, L-X; Haque, R; Harris, J W; Heppelmann, S; Hirsch, A; Hoffmann, G W; Hofman, D J; Horvat, S; Huang, B; Huang, H Z; Huang, X; Huck, P; Humanic, T J; Igo, G; Jacobs, W W; Jang, H; Judd, E G; Kabana, S; Kalinkin, D; Kang, K; Kauder, K; Ke, H W; Keane, D; Kechechyan, A; Kesich, A; Khan, Z H; Kikola, D P; Kisel, I; Kisiel, A; Koetke, D D; Kollegger, T; Konzer, J; Koralt, I; Kotchenda, L; Kraishan, A F; Kravtsov, P; Krueger, K; Kulakov, I; Kumar, L; Kycia, R A; Lamont, M A C; Landgraf, J M; Landry, K D; Lauret, J; Lebedev, A; Lednicky, R; Lee, J H; Levine, M J; Li, C; Li, W; Li, X; Li, X; Li, Y; Li, Z M; Lisa, M A; Liu, F; Ljubicic, T; Llope, W J; Lomnitz, M; Longacre, R S; Luo, X; Ma, G L; Ma, Y G; Madagodagettige Don, D M M D; Mahapatra, D P; Majka, R; Margetis, S; Markert, C; Masui, H; Matis, H S; McDonald, D; McShane, T S; Minaev, N G; Mioduszewski, S; Mohanty, B; Mondal, M M; Morozov, D A; Mustafa, M K; Nandi, B K; Nasim, Md; Nayak, T K; Nelson, J M; Nigmatkulov, G; Nogach, L V; Noh, S Y; Novak, J; Nurushev, S B; Odyniec, G; Ogawa, A; Oh, K; Ohlson, A; Okorokov, V; Oldag, E W; Olvitt, D L; Pachr, M; Page, B S; Pal, S K; Pan, Y X; Pandit, Y; Panebratsev, Y; Pawlak, T; Pawlik, B; Pei, H; Perkins, C; Peryt, W; Pile, P; Planinic, M; Pluta, J; Poljak, N; Porter, J; Poskanzer, A M; Pruthi, N K; Przybycien, M; Pujahari, P R; Putschke, J; Qiu, H; Quintero, A; Ramachandran, S; Raniwala, R; Raniwala, S; Ray, R L; Riley, C K; Ritter, H G; Roberts, J B; Rogachevskiy, O V; Romero, J L; Ross, J F; Roy, A; Ruan, L; Rusnak, J; Rusnakova, O; Sahoo, N R; Sahu, P K; Sakrejda, I; Salur, S; Sandweiss, J; Sangaline, E; Sarkar, A; Schambach, J; Scharenberg, R P; Schmah, A M; Schmidke, W B; Schmitz, N; Seger, J; Seyboth, P; Shah, N; Shahaliev, E; Shanmuganathan, P V; Shao, M; Sharma, B; Shen, W Q; Shi, S S; Shou, Q Y; Sichtermann, E P; Singaraju, R N; Skoby, M J; Smirnov, D; Smirnov, N; Solanki, D; Sorensen, P; Spinka, H M; Srivastava, B; Stanislaus, T D S; Stevens, J R; Stock, R; Strikhanov, M; Stringfellow, B; Sumbera, M; Sun, X; Sun, X M; Sun, Y; Sun, Z; Surrow, B; Svirida, D N; Symons, T J M; Szelezniak, M A; Takahashi, J; Tang, A H; Tang, Z; Tarnowsky, T; Thomas, J H; Timmins, A R; Tlusty, D; Tokarev, M; Trentalange, S; Tribble, R E; Tribedy, P; Trzeciak, B A; Tsai, O D; Turnau, J; Ullrich, T; Underwood, D G; Van Buren, G; van Nieuwenhuizen, G; Vandenbroucke, M; Vanfossen, J A; Varma, R; Vasconcelos, G M S; Vasiliev, A N; Vertesi, R; Videbæk, F; Viyogi, Y P; Vokal, S; Vossen, A; Wada, M; Wang, F; Wang, G; Wang, H; Wang, J S; Wang, X L; Wang, Y; Wang, Y; Webb, G; Webb, J C; Westfall, G D; Wieman, H; Wissink, S W; Witt, R; Wu, Y F; Xiao, Z; Xie, W; Xin, K; Xu, H; Xu, J; Xu, N; Xu, Q H; Xu, Y; Xu, Z; Yan, W; Yang, C; Yang, Y; Yang, Y; Ye, Z; Yepes, P; Yi, L; Yip, K; Yoo, I-K; Yu, N; Zawisza, Y; Zbroszczyk, H; Zha, W; Zhang, J B; Zhang, J L; Zhang, S; Zhang, X P; Zhang, Y; Zhang, Z P; Zhao, F; Zhao, J; Zhong, C; Zhu, X; Zhu, Y H; Zoulkarneeva, Y; Zyzak, M

    2014-04-25

    Rapidity-odd directed flow (v1) measurements for charged pions, protons, and antiprotons near midrapidity (y=0) are reported in sNN=7.7, 11.5, 19.6, 27, 39, 62.4, and 200 GeV Au+Au collisions as recorded by the STAR detector at the Relativistic Heavy Ion Collider. At intermediate impact parameters, the proton and net-proton slope parameter dv1/dy|y=0 shows a minimum between 11.5 and 19.6 GeV. In addition, the net-proton dv1/dy|y=0 changes sign twice between 7.7 and 39 GeV. The proton and net-proton results qualitatively resemble predictions of a hydrodynamic model with a first-order phase transition from hadronic matter to deconfined matter, and differ from hadronic transport calculations.

  12. Beam-Energy Dependence of Directed Flow of Protons, Antiprotons and Pions in Au+Au Collisions

    CERN Document Server

    Adamczyk, L; Agakishiev, G; Aggarwal, M M; Ahammed, Z; Alekseev, I; Alford, J; Anson, C D; Aparin, A; Arkhipkin, D; Aschenauer, E C; Averichev, G S; Banerjee, A; Beavis, D R; Bellwied, R; Bhasin, A; Bhati, A K; Bhattarai, P; Bichsel, H; Bielcik, J; Bielcikova, J; Bland, L C; Bordyuzhin, I G; Borowski, W; Bouchet, J; Brandin, A V; Brovko, S G; Bültmann, S; Bunzarov, I; Burton, T P; Butterworth, J; Caines, H; Sánchez, M Calderón de la Barca; Cebra, D; Cendejas, R; Cervantes, M C; Chaloupka, P; Chang, Z; Chattopadhyay, S; Chen, H F; Chen, J H; Chen, L; Cheng, J; Cherney, M; Chikanian, A; Christie, W; Chwastowski, J; Codrington, M J M; Contin, G; Cramer, J G; Crawford, H J; Cui, X; Das, S; Leyva, A Davila; De Silva, L C; Debbe, R R; Dedovich, T G; Deng, J; Derevschikov, A A; de Souza, R Derradi; Dhamija, S; di Ruzza, B; Didenko, L; Dilks, C; Ding, F; Djawotho, P; Dong, X; Drachenberg, J L; Draper, J E; Du, C M; Dunkelberger, L E; Dunlop, J C; Efimov, L G; Engelage, J; Engle, K S; Eppley, G; Eun, L; Evdokimov, O; Eyser, O; Fatemi, R; Fazio, S; Fedorisin, J; Filip, P; Finch, E; Fisyak, Y; Flores, C E; Gagliardi, C A; Gangadharan, D R; Garand, D; Geurts, F; Gibson, A; Girard, M; Gliske, S; Greiner, L; Grosnick, D; Gunarathne, D S; Guo, Y; Gupta, A; Gupta, S; Guryn, W; Haag, B; Hamed, A; Han, L-X; Haque, R; Harris, J W; Heppelmann, S; Hirsch, A; Hoffmann, G W; Hofman, D J; Horvat, S; Huang, B; Huang, H Z; Huang, X; Huck, P; Humanic, T J; Igo, G; Jacobs, W W; Jang, H; Judd, E G; Kabana, S; Kalinkin, D; Kang, K; Kauder, K; Ke, H W; Keane, D; Kechechyan, A; Kesich, A; Khan, Z H; Kikola, D P; Kisel, I; Kisiel, A; Koetke, D D; Kollegger, T; Konzer, J; Koralt, I; Kotchenda, L; Kraishan, A F; Kravtsov, P; Krueger, K; Kulakov, I; Kumar, L; Kycia, R A; Lamont, M A C; Landgraf, J M; Landry, K D; Lauret, J; Lebedev, A; Lednicky, R; Lee, J H; LeVine, M J; Li, C; Li, W; Li, X; Li, Y; Li, Z M; Lisa, M A; Liu, F; Ljubicic, T; Llope, W J; Lomnitz, M; Longacre, R S; Luo, X; Ma, G L; Ma, Y G; Don, D M M D Madagodagettige; Mahapatra, D P; Majka, R; Margetis, S; Markert, C; Masui, H; Matis, H S; McDonald, D; McShane, T S; Minaev, N G; Mioduszewski, S; Mohanty, B; Mondal, M M; Morozov, D A; Mustafa, M K; Nandi, B K; Nasim, Md; Nayak, T K; Nelson, J M; Nigmatkulov, G; Nogach, L V; Noh, S Y; Novak, J; Nurushev, S B; Odyniec, G; Ogawa, A; Oh, K; Ohlson, A; Okorokov, V; Oldag, E W; Olvitt, D L; Pachr, M; Page, B S; Pal, S K; Pan, Y X; Pandit, Y; Panebratsev, Y; Pawlak, T; Pawlik, B; Pei, H; Perkins, C; Peryt, W; Pile, P; Planinic, M; Pluta, J; Poljak, N; Porter, J; Poskanzer, A M; Pruthi, N K; Przybycien, M; Pujahari, P R; Putschke, J; Qiu, H; Quintero, A; Ramachandran, S; Raniwala, R; Raniwala, S; Ray, R L; Riley, C K; Ritter, H G; Roberts, J B; Rogachevskiy, O V; Romero, J L; Ross, J F; Roy, A; Ruan, L; Rusnak, J; Rusnakova, O; Sahoo, N R; Sahu, P K; Sakrejda, I; Salur, S; Sandweiss, J; Sangaline, E; Sarkar, A; Schambach, J; Scharenberg, R P; Schmah, A M; Schmidke, W B; Schmitz, N; Seger, J; Seyboth, P; Shah, N; Shahaliev, E; Shanmuganathan, P V; Shao, M; Sharma, B; Shen, W Q; Shi, S S; Shou, Q Y; Sichtermann, E P; Singaraju, R N; Skoby, M J; Smirnov, D; Smirnov, N; Solanki, D; Sorensen, P; Spinka, H M; Srivastava, B; Stanislaus, T D S; Stevens, J R; Stock, R; Strikhanov, M; Stringfellow, B; Sumbera, M; Sun, X; Sun, X M; Sun, Y; Sun, Z; Surrow, B; Svirida, D N; Symons, T J M; Szelezniak, M A; Takahashi, J; Tang, A H; Tang, Z; Tarnowsky, T; Thomas, J H; Timmins, A R; Tlusty, D; Tokarev, M; Trentalange, S; Tribble, R E; Tribedy, P; Trzeciak, B A; Tsai, O D; Turnau, J; Ullrich, T; Underwood, D G; Van Buren, G; van Nieuwenhuizen, G; Vandenbroucke, M; Vanfossen,, J A; Varma, R; Vasconcelos, G M S; Vasiliev, A N; Vertesi, R; Videbæk, F; Viyogi, Y P; Vokal, S; Vossen, A; Wada, M; Wang, F; Wang, G; Wang, H; Wang, J S; Wang, X L; Wang, Y; Webb, G; Webb, J C; Westfall, G D; Wieman, H; Wissink, S W; Witt, R; Wu, Y F; Xiao, Z; Xie, W; Xin, K; Xu, H; Xu, J; Xu, N; Xu, Q H; Xu, Y; Xu, Z; Yan, W; Yang, C; Yang, Y; Ye, Z; Yepes, P; Yi, L; Yip, K; Yoo, I-K; Yu, N; Zawisza, Y; Zbroszczyk, H; Zha, W; Zhang, J B; Zhang, J L; Zhang, S; Zhang, X P; Zhang, Y; Zhang, Z P; Zhao, F; Zhao, J; Zhong, C; Zhu, X; Zhu, Y H; Zoulkarneeva, Y; Zyzak, M

    2014-01-01

    Rapidity-odd directed flow($v_1$) measurements for charged pions, protons and antiprotons near mid-rapidity ($y=0$) are reported in $\\sqrt{s_{NN}} =$ 7.7, 11.5, 19.6, 27, 39, 62.4 and 200 GeV Au + Au collisions as recorded by the STAR detector at the Relativistic Heavy Ion Collider (RHIC). At intermediate impact parameters, the proton and net-proton slope parameter $dv_1/dy|_{y=0}$ shows a minimum between 11.5 and 19.6 GeV. In addition, the net-proton $dv_1/dy|_{y=0}$ changes sign twice between 7.7 and 39 GeV. The proton and net-proton results qualitatively resemble predictions of a hydrodynamic model with a first-order phase transition from hadronic matter to deconfined matter, and differ from hadronic transport calculations.

  13. The Antiproton Accumulator (AA)

    CERN Multimedia

    1980-01-01

    Section 06 - 08*) of the AA where the dispersion (and hence the horizontal beam size) is large. One can distinguish (left to right): A vacuum-tank, two bending magnets (BST06 and BST07 in blue) with a quadrupole (QDN07, in red) in between, another vacuum-tank, a wide quadrupole (QFW08) and a further tank . The tanks are covered with heating tape for bake-out. The tank left of BST06 contained the stack core pickup for stochastic cooling (see 7906193, 7906190, 8005051), the two other tanks served mainly as vacuum chambers in the region where the beam was large. Peter Zettwoch works on BST06. *) see: H. Koziol, Antiproton Accumulator Parameter List, PS/AA/Note 84-2 (1984)

  14. The anti-proton charge radius

    CERN Document Server

    Crivelli, P; Heiss, M W

    2016-01-01

    The upcoming operation of the Extra Low ENergy Antiprotons (ELENA) ring at CERN, the upgrade of the anti-proton decelerator (AD), and the installation in the AD hall of an intense slow positron beam with an expected flux of $10^{8}$ e$^+$/s will open the possibility for new experiments with anti-hydrogen ($\\bar{\\text{H}}$). Here we propose a scheme to measure the Lamb shift of $\\bar{\\text{H}}$. For a month of data taking, we anticipate an uncertainty of 100 ppm. This will provide a test of CPT and the first determination of the anti-proton charge radius at the level of 10%.

  15. Antiproton Accumulator (AA)

    CERN Multimedia

    Photographic Service

    1980-01-01

    The AA in its final stage of construction, before it disappeared from view under concrete shielding. Antiprotons were first injected, stochastically cooled and accumulated in July 1980. From 1981 on, the AA provided antiprotons for collisions with protons, first in the ISR, then in the SPS Collider. From 1983 on, it also sent antiprotons, via the PS, to the Low-Energy Antiproton Ring (LEAR). The AA was dismantled in 1997 and shipped to Japan.

  16. The ASACUSA experiment at CERN's AD antiproton decelerator catches antiprotons in helium, where the antiprotons replace electrons, giving exotics atoms.

    CERN Multimedia

    Loïez, P

    2000-01-01

    Photo 03: Laser beams are prepared for shooting at antiprotonic helium atoms. Left to right: Masaki Hori (Tokyo University) and John Eades (CERN). Photo 01: Dye laser triggered by "YAG" laser. Photo 02: Masaki Hori adjusting optical system of laser beams.

  17. The Antiproton Accumulator (AA)

    CERN Multimedia

    1980-01-01

    A section of the AA where the dispersion (and hence the horizontal beam size) is large. One can distinguish (left to right): A large vacuum-tank, a quadrupole (QDN09*), a bending magnet (BST08), another vacuum-tank, a wide quadrupole (QFW08) and (in the background) a further bending magnet (BST08). The tanks are covered with heating tape for bake-out. The tank left of QDN09 contained the kickers for stochastic pre-cooling (see 790621, 8002234, 8002637X), the other one served mainly as vacuum chamber in the region where the beam was large. Peter Zettwoch works on QFW08. * see: H. Koziol, Antiproton Accumulator Parameter List, PS/AA/Note 84-2 (1984) See under 7911303, 7911597X, 8004261 and 8202324. For photos of the AA in different phases of completion (between 1979 and 1982) see: 7911303, 7911597X, 8004261, 8004608X, 8005563X, 8005565X, 8006716X, 8006722X, 8010939X, 8010941X, 8202324, 8202658X, 8203628X .

  18. The CERN Low Energy Antiproton Ring (LEAR) project

    CERN Document Server

    Lefèvre, P; Plass, G

    1980-01-01

    The idea to add to the CERN Antiproton Accumulator (AA) a facility for experiments with dense and pure beams of low energy antiprotons has received enthusiastic support from many members of the physics community. After conceptual studies done since 1977 the following scheme was authorized in May 1980: Small batches of cooled antiprotons will be skimmed off from the AA at regular intervals, decelerated in the CERN PS and transferred into a small storage ring (LEAR). In its first stage LEAR will work as a beam stretcher providing a high duty cycle spill of 10/sup 6/ p/s into an experimental area. Future options (not yet authorized) foresee internal jet targets together with cooling, co-rotating beams of p and H, proton antiproton colliding beams, fast extraction with slowing down of p's to rest. A storage ring to fulfil this variety of tasks has to combine some unusual machine features which are summarized in the present report. (6 refs).

  19. Spencer-Attix water/medium stopping-power ratios for the dosimetry of proton pencil beams.

    Science.gov (United States)

    Gomà, C; Andreo, P; Sempau, J

    2013-04-21

    This paper uses Monte Carlo simulations to calculate the Spencer-Attix water/medium stopping-power ratios (sw, med) for the dosimetry of scanned proton pencil beams. It includes proton energies from 30 to 350 MeV and typical detection materials such as air (ionization chambers), radiochromic film, gadolinium oxysulfide (scintillating screens), silicon and lithium fluoride. Track-ends and particles heavier than protons were found to have a negligible effect on the water/air stopping-power ratios (sw, air), whereas the mean excitation energy values were found to carry the largest source of uncertainty. The initial energy spread of the beam was found to have a minor influence on the sw, air values in depth. The water/medium stopping-power ratios as a function of depth in water were found to be quite constant for air and radiochromic film-within 2.5%. Also, the sw, med values were found to have no clinically relevant dependence on the radial distance-except for the case of gadolinium oxysulfide and proton radiography beams. In conclusion, the most suitable detection materials for depth-dose measurements in water were found to be air and radiochromic film active layer, although a small correction is still needed to compensate for the different sw, med values between the plateau and the Bragg peak region. Also, all the detection materials studied in this work-except for gadolinium oxysulfide-were found to be suitable for lateral dose profiles and field-specific dose distribution measurements in water.

  20. The Antiproton Decelerator

    CERN Multimedia

    Laurent Guiraud

    1998-01-01

    A technician works on the Antiproton Decelerator (AD) ring. This machine slows down antiprotons so that they can combine with anti-electrons (positrons) and produce anti-hydrogen. Experiments are set up on the AD to attempt to store antihydrogen and investigate properties of anti-hydrogen, such as its mass.

  1. Fluence Correction Factors and Stopping Power Ratios for Clinical Ion Beams

    DEFF Research Database (Denmark)

    Lühr, Armin Christian; Hansen, David Christoffer; Sobolevsky, Nikolai;

    2011-01-01

    material to absorbed dose to water the water-to-material stopping power ratios (STPR) and the fluence correction factors (FCF) for the full charged particle spectra are needed. We determined STPR as well as FCF for water to graphite, bone (compact), and PMMA as a function of water equivalent depth, zw...

  2. An experimental study of the scatter correction by using a beam-stop-array algorithm with digital breast tomosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ye-Seul; Park, Hye-Suk; Kim, Hee-Joung [Yonsei University, Wonju (Korea, Republic of); Choi, Young-Wook; Choi, Jae-Gu [Korea Electrotechnology Research Institute, Ansan (Korea, Republic of)

    2014-12-15

    Digital breast tomosynthesis (DBT) is a technique that was developed to overcome the limitations of conventional digital mammography by reconstructing slices through the breast from projections acquired at different angles. In developing and optimizing DBT, The x-ray scatter reduction technique remains a significant challenge due to projection geometry and radiation dose limitations. The most common approach to scatter reduction is a beam-stop-array (BSA) algorithm; however, this method raises concerns regarding the additional exposure involved in acquiring the scatter distribution. The compressed breast is roughly symmetric, and the scatter profiles from projections acquired at axially opposite angles are similar to mirror images. The purpose of this study was to apply the BSA algorithm with only two scans with a beam stop array, which estimates the scatter distribution with minimum additional exposure. The results of the scatter correction with angular interpolation were comparable to those of the scatter correction with all scatter distributions at each angle. The exposure increase was less than 13%. This study demonstrated the influence of the scatter correction obtained by using the BSA algorithm with minimum exposure, which indicates its potential for practical applications.

  3. Antiprotonic atom formation and spectroscopy-ASACUSA experiment at CERN-AD

    CERN Document Server

    Widmann, E

    1999-01-01

    This talk describes the experiments on atomic spectroscopy and atomic collisions as proposed by the ASACUSA collaboration for the forthcoming AD facility at CERN. They consist of high-precision spectroscopy of antiprotonic atoms, the study of anti-protonic atom formation processes, and stopping power and ionization measurements in low-pressure gases. (18 refs).

  4. A systematic review of antiproton radiotherapy

    Directory of Open Access Journals (Sweden)

    Martin-Immanuel eBittner

    2014-01-01

    Full Text Available Antiprotons have been proposed as possible particles for radiotherapy; over the past years, the renewed interest in the potential biomedical relevance led to an increased research activity. It is the aim of this review to deliver a comprehensive overview regarding the evidence accumulated so far, analysing the background and depicting the current status of antiprotons in radiotherapy. A literature search has been conducted, including major scientific and commercial databases. All articles and a number of relevant conference abstracts published in the respective field have been included in this systematic review. The physical basis of antiproton radiotherapy is complex; however, the characterisation of the energy deposition profile supports its potential use in radiotherapy. Also the dosimetry improved considerably over the past few years. Regarding the biological properties, data on the effects on cells are presented; however, definite conclusions regarding the relative biological effectiveness cannot be made at the moment and radiobiological evidence of enhanced effectiveness remains scarce. In addition, there is new evidence supporting the potential imaging properties, for example for online dose verification. Clinical settings which might profit from the use of antiprotons have been further tracked. Judging from the evidence available so far, clinical constellations requiring optimal sparing in the entrance region of the beam and re-irradiations might profit most from antiproton radiotherapy. While several open questions remain to be answered, first steps towards a thorough characterisation of this interesting modality have been made.

  5. Experimental study of the water-to-air stopping power ratio of monoenergetic carbon ion beams for particle therapy.

    Science.gov (United States)

    Sánchez-Parcerisa, D; Gemmel, A; Jäkel, O; Parodi, K; Rietzel, E

    2012-06-07

    Reference dosimetry with ionization chambers requires a number of chamber-specific and beam-specific calibration factors. For carbon ion beams, IAEA report TRS-398 yields a total uncertainty of 3% in the determination of the absorbed dose to water, for which the biggest contribution arises from the water-to-air stopping power ratio (s(w, air)), with an uncertainty of 2%. The variation of (s(w, air)) along the treatment field has been studied in several Monte Carlo works presented over the last few years. Their results were, in all cases, strongly dependent on the choice of mean ionization potentials (I-values) for air and water. A smaller dependence of (s(w, air)) with penetration depth was observed. Since a consensus on I(w, air) and I(air) has not yet been reached, the validity of such studies for clinical use cannot be assessed independently. Our approach is based on a direct experimental measurement of water-equivalent thicknesses of different air gaps at different beam energies. A theoretical expression describing the variation of the stopping power ratio with kinetic energy, s(w,air)(E), was derived from the Bethe-Bloch formula and fit to the measured data, yielding a coherent pair of I(w) and I(air) values with I(air)/I(w) = 1.157 ± 0.023. Additionally, the data from five different beam energies were combined in an average value of s(w,air) = 1.132 ± 0.003 (statistical) ± 0.003 (variation over energy range), valid for monoenergetic carbon ion beams at the plateau area of the depth dose distribution. A detailed uncertainty analysis was performed on the data, in order to assess the limitations of the method, yielding an overall standard uncertainty below 1% in s(w,air)(E). Therefore, when properly combined with the appropriate models for the fragment spectra, our experimental work can contribute to narrow the uncertainty margins currently in use in absorbed dose to water determination for dosimetry of carbon ion beam radiotherapy.

  6. Treatment Plans for Antiproton Beams

    DEFF Research Database (Denmark)

    Holzscheiter, Michael; Bassler, Niels; Herrmann, Rochus;

    to determine the absolute dose deposited at each depth point we are now in the position to extract relative biological efficencies (RBE) vs. depth. Using Monte Carlo calculations and various biological assays we also have studied the effect of the peripheral dose deposited as a result of the isotropic...

  7. Validation of nuclear models in Geant4 using the halo of a proton pencil beam stopping in water

    CERN Document Server

    Hall, David C; Paganetti, Harald; Gottschalk, Bernard

    2015-01-01

    A proton pencil beam is associated with a surrounding low-dose envelope, originating from nuclear interactions. It is important for treatment planning systems to accurately model this envelope when performing dose calculations for pencil beam scanning treatments, and Monte Carlo (MC) codes are commonly used for this purpose. This work aims to validate the nuclear models employed by the Geant4 MC code, by comparing the simulated absolute dose distribution to a recent experiment of a 177 MeV proton pencil beam stopping in water. Impressive agreement is observed over five orders of magnitude, with both the shape and normalisation well modelled. The normalisations of two depth dose curves are lower than experiment, though this could be explained by an experimental positioning error. The Geant4 neutron production model is also verified in the distal region. The entrance dose is poorly modelled, suggesting an unaccounted upstream source of low-energy protons. Recommendations are given for a follow-up experiment whi...

  8. Three dimensional biological dose distribution of antiprotons

    Energy Technology Data Exchange (ETDEWEB)

    Tegami, Sara; Boll, Rebecca; Sellner, Stefan [Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany); Welsch, Carsten P. [Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany); Cockcroft Institute, University of Liverpool (United Kingdom); Holzscheiter, Michael H. [Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany); University of New Mexico, Albuquerque (United States)

    2010-07-01

    The goal of external beam cancer therapy is to destroy the tumour while sparing the healthy tissue around it. In hadron therapy, the dose profile of heavy charged particles satisfies this request, because most of the energy is deposited at the end of the particle path, in the Bragg peak. Antiprotons are even more promising, thanks to the extra energy released by annihilation when captured in a normal atom at the end of range. The aim of the AD-4/ACE experiment at CERN is to determine the increase in biological dose near the Bragg peak due to densely ionizing particles emanating from the annihilation of antiprotons. Initial experiments showed the damage to cells inflicted at the end of the beam for identical damage at the skin level to be four times higher for antiprotons than for protons. The radiation field in a spread-out Bragg peak produced with antiprotons is highly mixed and for proper dose planning knowledge of linear energy transfer (LET) and relative biological efficiency (RBE) at any point in the target is needed. We are studying a number of detection methods for their response to mixed radiation fields with the goal to obtain a direct measurement of the 3D LET distribution and report on first results.

  9. Relativistic high-current electron-beam stopping-power characterization in solids and plasmas: collisional versus resistive effects.

    Science.gov (United States)

    Vauzour, B; Santos, J J; Debayle, A; Hulin, S; Schlenvoigt, H-P; Vaisseau, X; Batani, D; Baton, S D; Honrubia, J J; Nicolaï, Ph; Beg, F N; Benocci, R; Chawla, S; Coury, M; Dorchies, F; Fourment, C; d'Humières, E; Jarrot, L C; McKenna, P; Rhee, Y J; Tikhonchuk, V T; Volpe, L; Yahia, V

    2012-12-21

    We present experimental and numerical results on intense-laser-pulse-produced fast electron beams transport through aluminum samples, either solid or compressed and heated by laser-induced planar shock propagation. Thanks to absolute K(α) yield measurements and its very good agreement with results from numerical simulations, we quantify the collisional and resistive fast electron stopping powers: for electron current densities of ≈ 8 × 10(10) A/cm(2) they reach 1.5 keV/μm and 0.8 keV/μm, respectively. For higher current densities up to 10(12)A/cm(2), numerical simulations show resistive and collisional energy losses at comparable levels. Analytical estimations predict the resistive stopping power will be kept on the level of 1 keV/μm for electron current densities of 10(14)A/cm(2), representative of the full-scale conditions in the fast ignition of inertially confined fusion targets.

  10. Centrality dependence of antiproton production in Au+Au collisions

    Energy Technology Data Exchange (ETDEWEB)

    Beavis, D.; Bennett, M.J.; Carroll, J.B.; Chiba, J.; Chikanian, A.; Crawford, H.; Cronqvist, M.; Dardenne, Y.; Debbe, R.; Doke, T.; Engelage, J.; Greiner, L.; Hallman, T.J.; Hayano, R.S.; Heckman, H.H.; Kashiwagi, T.; Kikuchi, J.; Kumar, S.; Kuo, C.; Lindstrom, P.J.; Mitchell, J.W.; Nagamiya, S.; Nagle, J.L.; Pope, J.K.; Stankus, P.; Tanaka, K.H.; Welsh, R.C.; Zhan, W. [Brookhaven National Laboratory, Upton, New York (United States)]|[A.W. Wright Nuclear Structure Laboratory, Yale University, New Haven, Connecticut (United States)]|[University of California at Los Angeles, Los Angeles California (United States)]|[National Laboratory for High Energy Physics (KEK), Tsukuba (Japan)]|[University of California Space Sciences Laboratory, Berkeley California (United States)]|[Waseda University, Tokyo (Japan)]|[University of Tokyo, Tokyo (Japan)]|[Lawrence Berkeley Laboratory, Berkeley California (United States)]|[Universities Space Sciences Research Association/Goddard Space Flight Center, Greenbelt, Maryland (United States)]|[Nevis Laboratory, Columbia University, Irvington, New York (United States)]|[Johns Hopkins University, Baltimore, Maryland (United States); (E878 Collaboration)

    1995-11-13

    We have measured the yields of antiprotons in Au+Au interactions in the rapidity range 1.2{lt}{ital y}{lt}2.8 as a function of centrality using a beam line spectrometer. The shapes of the invariant multiplicity distributions at {ital p}{sub {ital t}}=0 are used to explore the dynamics of antiproton production and annihilation. {copyright} {ital 1995} {ital The} {ital American} {ital Physical} {ital Society}.

  11. Heating nuclei with 8 GeV/c antiprotons

    CERN Document Server

    Lefort, T; Hsi, W C; Beaulieu, L; Viola, V E; Pienkowski, L; Korteling, R G; Leforest, R; Martin, E; Ramakrishnan, E; Rowland, D; Ruangma, A; Winchester, E M; Yennello, S J; Gushue, S; Remsberg, L P; Back, B B; Breuer, H

    1999-01-01

    Studies of the heating effect of 8 GeV/c pi sup - and antiproton beams incident on a sup 1 sup 9 sup 7 Au nucleus have been conducted at Brookhaven AGS accelerator with the Indiana Silicon Sphere 4 pi detector array. Enhanced energy deposition for antiprotons relative to negative pions and protons in this energy regime is observed. The results are consistent with predictions of an intranuclear cascade code.

  12. Stopping the unstoppable

    CERN Multimedia

    2002-01-01

    How do you stop two very high energy proton beams circulating in opposite directions around a 27-kilometre ring? The answer is the beam dumps. Two tunnels, pointing in opposite directions, are being constructed at point 6 of the LHC. These will allow the beams to be directed into two large beam dumps housed at the ends of the tunnels.

  13. Biological Effectiveness of Antiproton Annihilation

    DEFF Research Database (Denmark)

    Maggiore, C.; Agazaryan, N.; Bassler, N.;

    2004-01-01

    from the annihilation of antiprotons produce an increase in ‘‘biological dose’’ in the vicinity of the narrow Bragg peak for antiprotons compared to protons. This experiment is the first direct measurement of the biological effects of antiproton annihilation. The background, description, and status...

  14. Magnetic horn of the Antiproton Accumulator (AA)

    CERN Multimedia

    Photographic Service

    1988-01-01

    In the 1960s, the invention of this "current sheet lens" has helped to greatly improve the flux of neutrino beams. It was used again at the AA, collecting antiprotons from the production target at angles too large to fit into the acceptance of the AA. It was machined from aluminium to a thickness of 1.4 mm and pulsed at 400 kA for 15 microseconds (half-sine).

  15. Biological effectiveness of antiproton annihilation

    CERN Document Server

    Holzscheiter, Michael H.; Bassler, Niels; Beyer, Gerd; De Marco, John J.; Doser, Michael; Ichioka, Toshiyasu; Iwamoto, Keisuke S.; Knudsen, Helge V.; Landua, Rolf; Maggiore, Carl; McBride, William H.; Møller, Søren Pape; Petersen, Jorgen; Smathers, James B.; Skarsgard, Lloyd D.; Solberg, Timothy D.; Uggerhøj, Ulrik I.; Withers, H.Rodney; Vranjes, Sanja; Wong, Michelle; Wouters, Bradly G.

    2004-01-01

    We describe an experiment designed to determine whether or not the densely ionizing particles emanating from the annihilation of antiprotons produce an increase in “biological dose” in the vicinity of the narrow Bragg peak for antiprotons compared to protons. This experiment is the first direct measurement of the biological effects of antiproton annihilation. The experiment has been approved by the CERN Research Board for running at the CERN Antiproton Decelerator (AD) as AD-4/ACE (Antiproton Cell Experiment) and has begun data taking in June of 2003. The background, description and the current status of the experiment are given.

  16. Biological effectiveness of antiproton annihilation

    DEFF Research Database (Denmark)

    Holzscheiter, M.H.; Agazaryan, N.; Bassler, Niels;

    2004-01-01

    We describe an experiment designed to determine whether or not the densely ionizing particles emanating from the annihilation of antiprotons produce an increase in ‘‘biological dose’’ in the vicinity of the narrow Bragg peak for antiprotons compared to protons. This experiment is the first direct...... measurement of the biological effects of antiproton annihilation. The experiment has been approved by the CERN Research Board for running at the CERN Antiproton Decelerator (AD) as AD-4/ACE (Antiproton Cell Experiment) and has begun data taking in June of 2003. The background, description and the current...

  17. Precision Measurement of the Energies and Line Shapes of Antiprotonic Lyman and Balmer Transitions From Hydrogen and Helium Isotopes

    CERN Multimedia

    2002-01-01

    % PS207 \\\\ \\\\ For the study of the antiproton-proton and antiproton-nuclear spin-spin and spin-orbital interaction at threshold a high resolution measurement is proposed of the line shapes and energy shifts of antiprotonic K$\\alpha$ and L$\\alpha$ transitions of hydrogen and helium isotopes. The intense LEAR beam, stopped in the cyclotron trap at low gas pressure, provides a unique~X-ray~source with sufficient brightness. Charge coupled devices with their excellent background rejection and energy resolution allow a precise determination of the strong shifts and widths of the 1s hyperfine states of protonium, in addition the detection of the $\\bar{p}$D K$\\alpha$ transition should be possible. A focussing crystal spectrometer with a resolution $\\Delta$E/E of about l0$ ^- ^{4} $, which is superior in the accuracy of the energy determination by two orders of magnitude as compared to the present detection methods, will be used to measure the energies of the L$\\alpha$ transitions. This permits a first direct measure...

  18. Antiproton Annihilation Propulsion

    Science.gov (United States)

    1985-09-01

    propulsion system, a nuclear thermal hydrogen propulsion system, and an antiproton annihilation propulsion system. Since hauling chemical fuel into low...greater. Section 8.4 and Appendix B contain a comparative cost study of a storable chemical fuel propulsion system, a liquid oxygen/liquid hydrogen

  19. Antiproton Cancer Therapy

    DEFF Research Database (Denmark)

    Bassler, Niels

    of the secondary particles from the antiproton annihilation exihibt high-LET properties. Additionally, the high energy pions are leaving the target with minimal interactions and can be detected external to the body providing a real time feedback on the exact location of the energy deposition. In recent years, we...

  20. Coincidence studies with antiprotons

    Energy Technology Data Exchange (ETDEWEB)

    McGovern, M; Walters, H R J [Department of Applied Mathematics and Theoretical Physics, Queen' s University, Belfast BT7 1NN (United Kingdom); Assafrao, D; Mohallem, J R [Laboratorio de Atomos e Moleculas Especiais, Departamento de Fisica, ICEx, Universidade Federal de Minas Gerais, P.O Box 702, 30123-970 Belo Horizonte, MG (Brazil); Whelan, Colm T, E-mail: mmcgovern06@qub.ac.u [Department of Physics, Old Dominion University, Norfolk, VA 23529-0116 (United States)

    2010-02-01

    We present a short overview of a new method for calculating fully differential cross sections that is able to describe any aspect of coincidence measurements involving heavy projectiles. The method is based upon impact parameter close coupling with pseudostates. Examples from antiproton impact ionization are shown.

  1. Ionization chamber dosimetry of small photon fields: a Monte Carlo study on stopping-power ratios for radiosurgery and IMRT beams.

    Science.gov (United States)

    Sánchez-Doblado, F; Andreo, P; Capote, R; Leal, A; Perucha, M; Arráns, R; Núñez, L; Mainegra, E; Lagares, J I; Carrasco, E

    2003-07-21

    Absolute dosimetry with ionization chambers of the narrow photon fields used in stereotactic techniques and IMRT beamlets is constrained by lack of electron equilibrium in the radiation field. It is questionable that stopping-power ratio in dosimetry protocols, obtained for broad photon beams and quasi-electron equilibrium conditions, can be used in the dosimetry of narrow fields while keeping the uncertainty at the same level as for the broad beams used in accelerator calibrations. Monte Carlo simulations have been performed for two 6 MV clinical accelerators (Elekta SL-18 and Siemens Mevatron Primus), equipped with radiosurgery applicators and MLC. Narrow circular and Z-shaped on-axis and off-axis fields, as well as broad IMRT configured beams, have been simulated together with reference 10 x 10 cm2 beams. Phase-space data have been used to generate 3D dose distributions which have been compared satisfactorily with experimental profiles (ion chamber, diodes and film). Photon and electron spectra at various depths in water have been calculated, followed by Spencer-Attix (delta = 10 keV) stopping-power ratio calculations which have been compared to those used in the IAEA TRS-398 code of practice. For water/air and PMMA/air stopping-power ratios, agreements within 0.1% have been obtained for the 10 x 10 cm2 fields. For radiosurgery applicators and narrow MLC beams, the calculated s(w,air) values agree with the reference within +/-0.3%, well within the estimated standard uncertainty of the reference stopping-power ratios (0.5%). Ionization chamber dosimetry of narrow beams at the photon qualities used in this work (6 MV) can therefore be based on stopping-power ratios data in dosimetry protocols. For a modulated 6 MV broad beam used in clinical IMRT, s(w,air) agrees within 0.1% with the value for 10 x 10 cm2, confirming that at low energies IMRT absolute dosimetry can also be based on data for open reference fields. At higher energies (24 MV) the difference in s

  2. Ionization chamber dosimetry of small photon fields: a Monte Carlo study on stopping-power ratios for radiosurgery and IMRT beams

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez-Doblado, F [Radiofisica, Hospital Univ Virgen Macarena, Avda Dr Fedriani s/n, E-41009 Sevilla (Spain); Andreo, P [Division of Medical Radiation Physics, University of Stockholm, Karolinska Institute, PO Box 260, SE-171 76 Stockholm (Sweden); Capote, R [Radiofisica, Hospital Univ Virgen Macarena, Avda Dr Fedriani s/n, E-41009 Sevilla (Spain); Leal, A [Radiofisica, Hospital Univ Virgen Macarena, Avda Dr Fedriani s/n, E-41009 Sevilla (Spain); Perucha, M [Dpto Fisica Medica y Biofisica, F Medicina, Universidad Sevilla (Spain); Arrans, R [Radiofisica, Hospital Univ Virgen Macarena, Avda Dr Fedriani s/n, E-41009 Sevilla (Spain); Nunez, L [Radiofisica, Clinica Puerta de Hierro, Madrid (Spain); Mainegra, E [National Research Council, Ottawa (Canada); Lagares, J I [Radiofisica, Hospital Univ Virgen Macarena, Avda Dr Fedriani s/n, E-41009 Sevilla (Spain); Carrasco, E [Radiofisica, Hospital Univ Virgen Macarena, Avda Dr Fedriani s/n, E-41009 Sevilla (Spain)

    2003-07-21

    Absolute dosimetry with ionization chambers of the narrow photon fields used in stereotactic techniques and IMRT beamlets is constrained by lack of electron equilibrium in the radiation field. It is questionable that stopping-power ratio in dosimetry protocols, obtained for broad photon beams and quasi-electron equilibrium conditions, can be used in the dosimetry of narrow fields while keeping the uncertainty at the same level as for the broad beams used in accelerator calibrations. Monte Carlo simulations have been performed for two 6 MV clinical accelerators (Elekta SL-18 and Siemens Mevatron Primus), equipped with radiosurgery applicators and MLC. Narrow circular and Z-shaped on-axis and off-axis fields, as well as broad IMRT configured beams, have been simulated together with reference 10 x 10 cm{sup 2} beams. Phase-space data have been used to generate 3D dose distributions which have been compared satisfactorily with experimental profiles (ion chamber, diodes and film). Photon and electron spectra at various depths in water have been calculated, followed by Spencer-Attix ({delta} = 10 keV) stopping-power ratio calculations which have been compared to those used in the IAEA TRS-398 code of practice. For water/air and PMMA/air stopping-power ratios, agreements within 0.1% have been obtained for the 10 x 10 cm{sup 2} fields. For radiosurgery applicators and narrow MLC beams, the calculated s{sub w,air} values agree with the reference within {+-}0.3%, well within the estimated standard uncertainty of the reference stopping-power ratios (0.5%). Ionization chamber dosimetry of narrow beams at the photon qualities used in this work (6 MV) can therefore be based on stopping-power ratios data in dosimetry protocols. For a modulated 6 MV broad beam used in clinical IMRT, s{sub w,air} agrees within 0.1% with the value for 10 x 10 cm{sup 2}, confirming that at low energies IMRT absolute dosimetry can also be based on data for open reference fields. At higher energies (24

  3. Laser spectroscopy of the antiprotonic helium atom – its energy levels and state lifetimes

    CERN Document Server

    Hidetoshi, Yamaguchi

    2003-01-01

    The antiprotonic atom is a three-body exotic system consisting of an antiproton, an electron and a helium nucleus. Its surprising longevity was found and has been studied for more than 10 years. In this work, transition energies and lifetimes of this exotic atom were systematically studied by using the antiproton beam of AD(Antiproton Decelerator) facility at CERN, with an RFQ antiproton decelerator, a narrow-bandwidth laser, Cerenkov counters with fast-response photomultiplier tubes, and cryogenic helium target systems. Thirteen transition energies were determined with precisions of better than 200 ppb by a laser spectroscopy method, together with the elimination of the shift effect caused by collisions with surrounding atoms. Fifteen lifetimes (decay rates) of short-lived states were determined from the time distributions of the antiproton-annihilation signals and the resonance widths of the atomic spectral lines. The relation between the magnitude of the decay rates and the transition multipolarity was inv...

  4. Energy and centrality dependence of antiproton and proton production in relativistic Pb+Pb collisions at the CERN SPS

    CERN Document Server

    Alt, C; Baatar, B.; Barna, D.; Bartke, J.; Betev, L.; Bialkowska, H.; Blume, C.; Boimska, B.; Botje, M.; Bracinik, J.; Bramm, R.; Buncic, P.; Cerny, V.; Christakoglou, P.; Chvala, O.; Cramer, J.G.; Csato, P.; Dinkelaker, P.; Eckardt, V.; Flierl, D.; Fodor, Z.; Foka, P.; Friese, V.; Gal, J.; Gazdzicki, M.; Genchev, V.; Georgopoulos, G.; Gladysz, E.; Grebieszkow, K.; Hegyi, S.; Hohne, C.; Kadija, K.; Karev, A.; Kliemant, M.; Kniege, S.; Kolesnikov, V.I.; Kornas, E.; Korus, R.; Kowalski, M.; Kraus, I.; Kreps, M.; Laslo, A.; van Leeuwen, M.; Levai, P.; Litov, L.; Lungwitz, B.; Makariev, M.; Malakhov, A.I.; Mateev, M.; Melkumov, G.L.; Mischke, A.; Mitrovski, M.; Molnar, J.; Mrowczynski, St.; Nicolic, V.; Palla, G.; Panagiotou, A.D.; Panayotov, D.; Petridis, A.; Pikna, M.; Prindle, D.; Puhlhofer, F.; Renfordt, R.; Roland, C.; Roland, G.; Rybczynski, M.; Rybicki, A.; Sandoval, A.; Schmitz, N.; Schuster, T.; Seyboth, P.; Sikler, F.; Sitar, B.; Skrzypczak, E.; Stefanek, G.; Stock, R.; Strabel, C.; Strobele, H.; Susa, T.; Szentpetery, I.; Sziklai, J.; Szymanski, P.; Trubnikov, V.; Varga, D.; Vassiliou, M.; Veres, G.I.; Vesztergombi, G.; Vranic, D.; Wetzler, A.; Wlodarczyk, Z.; Yoo, I.K.; Zimanyi, J.

    2005-01-01

    The transverse mass distributions for antiprotons are measured at midrapidity for minimum bias Pb+Pb collisions at 158A GeV and for central Pb+Pb collisions at 20, 30, 40 and 80 A GeV beam energies in the NA49 experiment at the CERN SPS. The rapidity density, inverse slope parameter and mean transverse mass derived from the transverse mass distributions are studied as a function of the incident energy and the collision centrality and compared to the relevant proton data. The shapes of the m_T distributions of antiprotons and protons are very similar. The ratios of the particle yields, antiproton/proton and antilambda/antiproton, are also analysed. The antiproton/proton ratio exhibits an increase with diminishing centrality and a steep rise with increasing beam energy. The antilambda/antiproton ratio increases beyond unity with decreasing beam energy.

  5. Relationship between electron density and effective densities of body tissues for stopping, scattering and nuclear interaction of proton and ion beams

    CERN Document Server

    Kanematsu, Nobuyuki

    2011-01-01

    In treatment planning of charged-particle radiotherapy, patient heterogeneity is normally modeled as variable-density water to best reproduce the stopping power. This water-based model would cause substantial errors in multiple scattering and nuclear interaction as body tissues may deviate from water in elemental compositions. In this study, we physically defined distinctive effective densities for stopping, scattering, and nuclear interactions of proton and ions and constructed their conversion functions to correct the water-based model, using the standard elemental composition data for body tissues. As we took the electron density for the reference in the formulation, these conversion functions are generally valid for treatment planning systems that normally have a function to convert CT number to electron density or stopping-power ratio. The proposed extension in heterogeneity correction will enable accurate beam dose calculation without seriously sacrificing simplicity or efficiency of the water-based mod...

  6. Atomic Spectroscopy and Collisions Using Slow Antiprotons \\\\ ASACUSA Collaboration

    CERN Multimedia

    Matsuda, Y; Lodi-rizzini, E; Kuroda, N; Schettino, G; Hori, M; Pirkl, W; Mascagna, V; Malbrunot, C L S; Yamazaki, Y; Eades, J; Simon, M; Massiczek, O; Sauerzopf, C; Nagata, Y; Uggerhoj, U I; Mc cullough, R W; Toekesi, K M; Venturelli, L; Widmann, E; Zmeskal, J; Kanai, Y; Hayano, R; Knudsen, H; Kristiansen, H; Todoroki, K; Bartel, M A; Moller, S P; Charlton, M; Leali, M; Diermaier, M; Kolbinger, B

    2002-01-01

    ASACUSA (\\underline{A}tomic \\underline{S}pectroscopy \\underline{A}nd \\underline{C}ollisions \\underline{U}sing \\underline{S}low \\underline{A}ntiprotons) is a collaboration between a number of Japanese and European research institutions, with the goal of studying bound and continuum states of antiprotons with simple atoms.\\\\ Three phases of experimentation are planned for ASACUSA. In the first phase, we use the direct $\\overline{p}$ beam from AD at 5.3 MeV and concentrate on the laser and microwave spectroscopy of the metastable antiprotonic helium atom, $\\overline{p}$He$^+$, consisting of an electron and antiproton bound by the Coulomb force to the helium nucleus. Samples of these are readily created by bringing AD antiproton beam bunches to rest in helium gas. With the help of techniques developed at LEAR for resonating high precision laser beams with antiproton transitions in these atoms, ASACUSA achieved several of these first-phase objectives during a few short months of AD operation in 2000. Six atomic tr...

  7. Antiproton Radiation Therapy

    DEFF Research Database (Denmark)

    Bassler, Niels; Holzscheiter, Michael H.; Petersen, Jørgen B.B.

    2007-01-01

    the radiobiological properties using antiprotons at 50 and 125 MeV from the Antiproton Decelerator (AD) at CERN. Dosimetry experiments were carried out with ionization chambers, alanine pellets and radiochromic film. Radiobiological experiments were done with Chinese V79 WNRE hamster cells. Monte Carlo particle...... transport codes were investigated and compared with results obtained from the ionization chambers and alanine pellets. A track structure model have been applied on the calculated particle spectrum, and been used to predict the LET-dependent response of the alanine pellets. The particle transport program...... FLUKA produced data which were in excellent agreement with our ionization chamber measurements, and in good agreement with our alanine measurements. FLUKA is now being used to generate a wide range of depth dose data at several energies, including secondary particle–energy spectra, which will be used...

  8. Bubble chamber: antiproton annihilation

    CERN Multimedia

    1971-01-01

    These images show real particle tracks from the annihilation of an antiproton in the 80 cm Saclay liquid hydrogen bubble chamber. A negative kaon and a neutral kaon are produced in this process, as well as a positive pion. The invention of bubble chambers in 1952 revolutionized the field of particle physics, allowing real tracks left by particles to be seen and photographed by expanding liquid that had been heated to boiling point.

  9. Antiproton compression and radial measurements

    CERN Document Server

    Andresen, G B; Bowe, P D; Bray, C C; Butler, E; Cesar, C L; Chapman, S; Charlton, M; Fajans, J; Fujiwara, M C; Funakoshi, R; Gill, D R; Hangst, J S; Hardy, W N; Hayano, R S; Hayden, M E; Humphries, A J; Hydomako, R; Jenkins, M J; Jorgensen, L V; Kurchaninov, L; Lambo, R; Madsen, N; Nolan, P; Olchanski, K; Olin, A; Page R D; Povilus, A; Pusa, P; Robicheaux, F; Sarid, E; Seif El Nasr, S; Silveira, D M; Storey, J W; Thompson, R I; Van der Werf, D P; Wurtele, J S; Yamazaki, Y

    2008-01-01

    Control of the radial profile of trapped antiproton clouds is critical to trapping antihydrogen. We report detailed measurements of the radial manipulation of antiproton clouds, including areal density compressions by factors as large as ten, achieved by manipulating spatially overlapped electron plasmas. We show detailed measurements of the near-axis antiproton radial profile, and its relation to that of the electron plasma. We also measure the outer radial profile by ejecting antiprotons to the trap wall using an octupole magnet.

  10. ALPHA freezes antiprotons

    CERN Multimedia

    CERN Bulletin

    2010-01-01

    Laboratories like CERN can routinely produce many different types of antiparticles. In 1995, the PS210 experiment formed the first antihydrogen atoms and a few years later, in 2002, ATRAP and ATHENA were already able to produce several thousand of them. However, no experiment in the world has succeeded in ‘trapping’ these anti-atoms in order to study them. This is the goal of the ALPHA experiment, which has recently managed to cool down the antiprotons to just a few Kelvin. This represents a major step towards trapping the anti-atom, thus opening a new avenue into the investigation of antimatter properties.   Members of the ALPHA collaboration working on the apparatus in the Antiproton Decelerator experimental hall at CERN. Just like the atom, the anti-atom is neutral. Unlike the atom, the anti-atom is made up of antiprotons (as opposed to protons in the atom) and positrons (as opposed to electrons). In order to thoroughly study the properties of the anti-atoms, scien...

  11. Measurements of output factors with different detector types and Monte Carlo calculations of stopping-power ratios for degraded electron beams.

    Science.gov (United States)

    Björk, Peter; Knöös, Tommy; Nilsson, Per

    2004-10-07

    The aim of the present study was to investigate three different detector types (a parallel-plate ionization chamber, a p-type silicon diode and a diamond detector) with regard to output factor measurements in degraded electron beams, such as those encountered in small-electron-field radiotherapy and intraoperative radiation therapy (IORT). The Monte Carlo method was used to calculate mass collision stopping-power ratios between water and the different detector materials for these complex electron beams (nominal energies of 6, 12 and 20 MeV). The diamond detector was shown to exhibit excellent properties for output factor measurements in degraded beams and was therefore used as a reference. The diode detector was found to be well suited for practical measurements of output factors, although the water-to-silicon stopping-power ratio was shown to vary slightly with treatment set-up and irradiation depth (especially for lower electron energies). Application of ionization-chamber-based dosimetry, according to international dosimetry protocols, will introduce uncertainties smaller than 0.3% into the output factor determination for conventional IORT beams if the variation of the water-to-air stopping-power ratio is not taken into account. The IORT system at our department includes a 0.3 cm thin plastic scatterer inside the therapeutic beam, which furthermore increases the energy degradation of the electrons. By ignoring the change in the water-to-air stopping-power ratio due to this scatterer, the output factor could be underestimated by up to 1.3%. This was verified by the measurements. In small-electron-beam dosimetry, the water-to-air stopping-power ratio variation with field size could mostly be ignored. For fields with flat lateral dose profiles (>3 x 3 cm2), output factors determined with the ionization chamber were found to be in close agreement with the results of the diamond detector. For smaller field sizes the lateral extension of the ionization chamber hampers

  12. X-rays from antiprotonic sup 3 He and sup 4 He

    Energy Technology Data Exchange (ETDEWEB)

    Schneider, M.; Bacher, R.; Bluem, P.; Gotta, D.; Heitlinger, K.; Kunold, W.; Rohmann, D. (Kernforschungszentrum Karlsruhe GmbH (Germany, F.R.). Inst. fuer Kernphysik Karlsruhe Univ. (T.H.) (Germany, F.R.). Inst. fuer Experimentelle Kernphysik); Egger, J.; Simons, L.M. (Paul Scherrer Inst. (PSI), Villigen (Switzerland)); Elsener, K. (European Organization for Nuclear Research, Geneva (Switzerland))

    1991-02-01

    Antiprotonic X-rays from the helium isotopes have been observed at pressures of 36, 72, 375 and 600 mbar. The antiproton beam from LEAR with momenta of 309 and 202 MeV/c has been stopped at these pressures using the cyclotron trap. The X-rays were detected with Si(Li) and intrinsic Ge semiconductor detectors. Absolute X-ray yields were determined and the strong-interaction 2p shifts and the 2p and 3d broadenings measured to be {epsilon}{sub 2p}=(-17{plus minus}4) eV, {Gamma}{sub 2p}=(25{plus minus}9) eV and {Gamma}{sub 3d}=(2.14{plus minus}0.18) meV for anti p{sup 3}He and {epsilon}{sub 2p}=(-18{plus minus}2) eV, {Gamma}{sub 2p}=(45{plus minus}5) eV and {Gamma}{sub 3d}=(2.36{plus minus}0.10) meV for anti p{sup 4}He. (orig.).

  13. Many Facets of Strangeness Nuclear Physics with Stored Antiprotons

    CERN Document Server

    Pochodzalla, Josef; Lorente, Alicia Sanchez; Rojo, Marta Martinez; Steinen, Marcell; Gerl, Jürgen; Kojouharova, Jasmina; Kojouharova, Ivan

    2016-01-01

    Stored antiprotons beams in the GeV range represent a unparalleled factory for hyperon-antihyperon pairs. Their outstanding large production probability in antiproton collisions will open the floodgates for a series of new studies of strange hadronic systems with unprecedented precision. The behavior of hyperons and -- for the first time -- of antihyperons in nuclear systems can be studied under well controlled conditions. The exclusive production of $\\Lambda\\bar{\\Lambda}$ and $\\Sigma^-\\bar{\\Lambda}$ pairs in antiproton-nucleus interactions probe the neutron and proton distribution in the nuclear periphery and will help to sample the neutron skin. For the first time, high resolution $\\gamma$-spectroscopy of doubly strange nuclei will be performed, thus complementing measurements of ground state decays of double hypernuclei with mesons beams at J-PARC or possible decays of particle unstable hypernuclei in heavy ion reactions. High resolution spectroscopy of multistrange $\\Xi$-atoms are feasible and even the pr...

  14. Segmented scintillation detectors with silicon photomultiplier readout for measuring antiproton annihilations

    CERN Document Server

    Sótér, A; Kobayashi, T; Barna, D; Horvath, D; Hori, M

    2014-01-01

    The Atomic Spectroscopy and Collisions Using Slow Antiprotons (ASACUSA) experiment at the Antiproton Decelerator (AD) facility of CERN constructed segmented scintillators to detect and track the charged pions which emerge from antiproton annihilations in a future superconducting radiofrequency Paul trap for antiprotons. A system of 541 cast and extruded scintillator bars were arranged in 11 detector modules which provided a spatial resolution of 17 mm. Green wavelength-shifting fibers were embedded in the scintillators, and read out by silicon photomultipliers which had a sensitive area of 1 x 1 mm^2. The photoelectron yields of various scintillator configurations were measured using a negative pion beam of momentum p ~ 1 GeV/c. Various fibers and silicon photomultipliers, fiber end terminations, and couplings between the fibers and scintillators were compared. The detectors were also tested using the antiproton beam of the AD. Nonlinear effects due to the saturation of the silicon photomultiplier were seen a...

  15. Baryon Stopping in Au+Au and p+p collisions at 62 and 200 GeV

    CERN Document Server

    Dalsgaard, Hans Hjersing

    2009-01-01

    BRAHMS has measured rapidity density distributions of protons and antiprotons in both p+p and Au+Au collisions at 62 GeV and 200 GeV. From these distributions the yields of so-called "net-protons", that is the difference between the proton and antiproton yields, can be determined. The rapidity dependence of the net-proton yields from peripheral Au+Au collisions is found to have a similar behaviour to that found for the p+p results, while a quite different rapidity dependence is found for central Au+Au collisions. The net-proton distributions can be used together with model calculations to find the net-baryon yields as a function of rapidity, thus yielding information on the average rapidity loss of beam particles, the baryon transport properties of the medium, and the amount of "stopping" in these collisions.

  16. Possibility of resonant capture of antiprotons by highly charged hydrogenlike ions

    Science.gov (United States)

    Genkin, M.; Lindroth, E.

    2009-02-01

    Recently, an experimental setup was proposed by Lapierre et al. [ Physics with ultra slow antiproton beams, AIP Conference Proceedings (2005), Vol. 793, p. 361] which would allow antiprotons and highly charged ions to collide repeatedly in an electron beam ion trap (EBIT) due to a nested trap configuration. As mentioned by the authors, such a setup may open the possibility to study antiproton capture into well-defined states through a resonant process which involves simultaneous electron excitation. In the present work, we give some theoretical estimations of the feasibility of that process.

  17. ANTIPROTONS PRODUCED IN SUPERNOVA REMNANTS

    Energy Technology Data Exchange (ETDEWEB)

    Berezhko, E. G.; Ksenofontov, L. T., E-mail: ksenofon@ikfia.sbras.ru [Yu. G. Shafer Institute of Cosmophysical Research and Aeronomy, 31 Lenin Avenue, 677891 Yakutsk (Russian Federation)

    2014-08-20

    We present the energy spectrum of an antiproton cosmic ray (CR) component calculated on the basis of the nonlinear kinetic model of CR production in supernova remnants (SNRs). The model includes the reacceleration of antiprotons already existing in the interstellar medium as well as the creation of antiprotons in nuclear collisions of accelerated protons with gas nuclei and their subsequent acceleration by SNR shocks. It is shown that the production of antiprotons in SNRs produces a considerable effect in their resultant energy spectrum, making it essentially flatter above 10 GeV so that the spectrum at TeV energies increases by a factor of 5. The calculated antiproton spectrum is consistent with the PAMELA data, which correspond to energies below 100 GeV. As a consistency check, we have also calculated within the same model the energy spectra of secondary nuclei and show that the measured boron-to-carbon ratio is consistent with the significant SNR contribution.

  18. X-rays from anti-protonic hydrogen and deuterium

    Energy Technology Data Exchange (ETDEWEB)

    Gorringe, T.P.; Davies, J.D.; Lowe, J.; Nelson, J.M.; Playfer, S.M.; Pyle, G.J.; Squier, G.T.A.; Baker, C.A.; Batty, C.J.; Clark, S.A.; Kilvington, A.I.; Moir, J.; Sakamoto, S.; Welsh, R.E.; Winter, R.G.; Lingeman, E.W.A.

    1985-11-07

    Antiprotons from the LEAR facility at CERN were stopped in targets of gaseous H/sub 2/ or D/sub 2/. Yields of L X-rays were measured. K-series from anti p-p atoms were observed. The measured shift and width for the 1s level are ..delta..Esub(1s)=-0.73+-0.15 keV and GAMMAsub(1s)=0.85+-0.39 keV. (orig.).

  19. Strangeness production in antiproton nucleus interactions

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, S. [Rice Univ., Houston, TX (United States). Bonner Nuclear Labs.; Bonner, B.E. [Rice Univ., Houston, TX (United States). Bonner Nuclear Labs.; Buchanan, J.A. [Rice Univ., Houston, TX (United States). Bonner Nuclear Labs.; Carter, P. [Rice Univ., Houston, TX (United States). Bonner Nuclear Labs.; Chan, C.S.; Clement, J.M.; Eiseman, S.E.; Empl, A.; Etkin, A.; Foley, K.J.; Hackenburg, R.W.; Hallman, T.J.; Kramer, M.A.; Lindenbaum, S.J.; Longacre, R.S.; Love, W.A.; Madansky, L.; Mattingly, A.C.; Morris, T.W.; Mutchler, G.S.; Peaslee, D.C.; Platner, E.D.; Saulys, A.C.; Toshkov, S.

    1997-06-01

    Results on the measurement of inclusive K{sub S}{sup 0}, {Lambda} and {Lambda} production cross sections and rapidity distributions for antiproton interactions on lead, copper and carbon nuclear targets at beam momenta of 5.2, 7.0 and 8.8 GeV/c are reported. Simulations employing a conventional intra-nuclear cascade model were able to reproduce the experimental results. Hence, no compelling evidence for the formation of exotic quark-gluon states of matter was found. (orig.).

  20. Perspectives for low energy antiproton physics at FAIR

    CERN Document Server

    Widmann, Eberhard

    2014-01-01

    The CRYRING accelerator, previously located at the Manne Siegbahn Laboratory of Stockholm University, has been chosen by the FLAIR collaboration as the central accelerator for the planned facility. It has been modified to allow for high-energy injection and extraction and is capable of providing fast and slow extracted beams of antiprotons and highly charged ions. It is currently being installed at the ESR of GSI Darmstadt where it can be used with highly charged ions. The future possibilities for its use with slow antiprotons will be discussed.

  1. Analytical model for ion stopping power and range in the therapeutic energy interval for beams of hydrogen and heavier ions

    Science.gov (United States)

    Donahue, William; Newhauser, Wayne D.; Ziegler, James F.

    2016-09-01

    Many different approaches exist to calculate stopping power and range of protons and heavy charged particles. These methods may be broadly categorized as physically complete theories (widely applicable and complex) or semi-empirical approaches (narrowly applicable and simple). However, little attention has been paid in the literature to approaches that are both widely applicable and simple. We developed simple analytical models of stopping power and range for ions of hydrogen, carbon, iron, and uranium that spanned intervals of ion energy from 351 keV u-1 to 450 MeV u-1 or wider. The analytical models typically reproduced the best-available evaluated stopping powers within 1% and ranges within 0.1 mm. The computational speed of the analytical stopping power model was 28% faster than a full-theoretical approach. The calculation of range using the analytic range model was 945 times faster than a widely-used numerical integration technique. The results of this study revealed that the new, simple analytical models are accurate, fast, and broadly applicable. The new models require just 6 parameters to calculate stopping power and range for a given ion and absorber. The proposed model may be useful as an alternative to traditional approaches, especially in applications that demand fast computation speed, small memory footprint, and simplicity.

  2. Analytical model for ion stopping power and range in the therapeutic energy interval for beams of hydrogen and heavier ions.

    Science.gov (United States)

    Donahue, William; Newhauser, Wayne D; Ziegler, James F

    2016-09-01

    Many different approaches exist to calculate stopping power and range of protons and heavy charged particles. These methods may be broadly categorized as physically complete theories (widely applicable and complex) or semi-empirical approaches (narrowly applicable and simple). However, little attention has been paid in the literature to approaches that are both widely applicable and simple. We developed simple analytical models of stopping power and range for ions of hydrogen, carbon, iron, and uranium that spanned intervals of ion energy from 351 keV u(-1) to 450 MeV u(-1) or wider. The analytical models typically reproduced the best-available evaluated stopping powers within 1% and ranges within 0.1 mm. The computational speed of the analytical stopping power model was 28% faster than a full-theoretical approach. The calculation of range using the analytic range model was 945 times faster than a widely-used numerical integration technique. The results of this study revealed that the new, simple analytical models are accurate, fast, and broadly applicable. The new models require just 6 parameters to calculate stopping power and range for a given ion and absorber. The proposed model may be useful as an alternative to traditional approaches, especially in applications that demand fast computation speed, small memory footprint, and simplicity.

  3. HEDgeHOB High-energy density matter generated by heavy ion beams at the future facility for antiprotons and ion research

    CERN Document Server

    Tahir, N A; Shutov, A; Lomonosov, I V; Gryaznov, V; Piriz, A R; Wouchuk, G; Deutsch, C; Fortov, V E; Hoffmann, D H H; Schmidt, R

    2007-01-01

    This paper presents an overview of the theoretical work that has been carried out during the past few years to assess the capabilities of intense heavy ion beams to induce states of High-Energy Density (HED) in matter. This work has shown that two different experimental schemes can be used to study HED physics employing intense ion beams. These schemes have been named HIHEX [Heavy Ion Heating and EXpansion] and LAPLAS [LAboratory PLAnetary Sciences], respectively. The first scheme involves isochoric and uniform heating and subsequent isentropic expansion of matter while the latter deals with low entropy compression of matter using multiple shock reflection technique. This work has been done within the framework of the HEDgeHOB [High Energy Density Matter Generated by Heavy Ion Beams] collaboration that has been formed to organize and facilitate construction of experimental facilities and later to perform experimental work in the field of HED matter at the future accelerator facility, FAIR [Facility for Antipr...

  4. The PANDA Experiment at FAIR - Subatomic Physics with Antiprotons

    CERN Document Server

    Messchendorp, Johan

    2016-01-01

    The non-perturbative nature of the strong interaction leads to spectacular phenomena, such as the formation of hadronic matter, color confinement, and the generation of the mass of visible matter. To get deeper insight into the underlying mechanisms remains one of the most challenging tasks within the field of subatomic physics. The antiProton ANnihilations at DArmstadt (PANDA) collaboration has the ambition to address key questions in this field by exploiting a cooled beam of antiprotons at the High Energy Storage Ring (HESR) at the future Facility for Antiproton and Ion Research (FAIR) combined with a state-of-the-art and versatile detector. This contribution will address some of the unique features of PANDA that give rise to a promising physics program together with state-of-the-art technological developments.

  5. The Floor's the Limit (Antiproton energies to hit new low)

    CERN Multimedia

    2000-01-01

    Celebrating the success of the RFQ in Aarhus. Left to right: Alessanda Lombardi (CERN), Iouri Bylinskii (CERN), Alex Csete (Aarhus), Ulrik Uggerhøj (Aarhus), Ryu Hayano (Tokyo, spokesman ASACUSA), Helge Knudsen (Aarhus), Werner Pirkl (CERN), Ryan Thompson (Aarhus), Søren P. Møller (Aarhus). Although in particle physics we are accustomed to strive for higher and higher energies, this is not always the most interesting thing to do with antiprotons. Indeed, as recent issues of the Bulletin have suggested, the signpost on the road to a closer look at the antiproton points towards ever-lower energies. The CERN Antiproton Decelerator decelerates antipro-tons emerging from a target placed in the path of a 26 GeV/c proton beam from 90 % of to about 10 % of the speed of light. However, even this is far too fast for many of the most interesting experiments on antiprotons planned by Danish and Japanese members of the ASACUSA collaboration. Tokyo University has therefore financed the con...

  6. Autoresonant Excitation of Antiproton Plasmas

    CERN Document Server

    Andresen, Gorm B; Baquero-Ruiz, Marcelo; Bertsche, William; Bowe, Paul D; Butler, Eoin; Carpenter, P T; Cesar, Claudio L; Chapman, Steven; Charlton, Michael; Fajans, Joel; Friesen, Tim; Fujiwara, Makoto C; Gill, David R; Hangst, Jeffrey S; Hardy, Walter N; Hayden, Michael E; Humphries, Andrew J; Hurt, J L; Hydomako, Richard; Jonsell, Svante; Madsen, Niels; Menary, Scott; Nolan, Paul; Olchanski, Konstantin; Olin, Art; Povilus, Alexander; Pusa, Petteri; Robicheaux, Francis; Sarid, Eli; Silveira, Daniel M; So, Chukman; Storey, James W; Thompson, Robert I; van der Werf, Dirk P; Wurtele, Jonathan S; Yamazaki, Yasunori

    2011-01-01

    We demonstrate controllable excitation of the center-of-mass longitudinal motion of a thermal antiproton plasma using a swept-frequency autoresonant drive. When the plasma is cold, dense, and highly collective in nature, we observe that the entire system behaves as a single-particle nonlinear oscillator, as predicted by a recent theory. In contrast, only a fraction of the antiprotons in a warm plasma can be similarly excited. Antihydrogen was produced and trapped by using this technique to drive antiprotons into a positron plasma, thereby initiating atomic recombination.

  7. A reservoir trap for antiprotons

    CERN Document Server

    Smorra, Christian; Franke, Kurt; Nagahama, Hiroki; Schneider, Georg; Higuchi, Takashi; Van Gorp, Simon; Blaum, Klaus; Matsuda, Yasuyuki; Quint, Wolfgang; Walz, Jochen; Yamazaki, Yasunori; Ulmer, Stefan

    2015-01-01

    We have developed techniques to extract arbitrary fractions of antiprotons from an accumulated reservoir, and to inject them into a Penning-trap system for high-precision measurements. In our trap-system antiproton storage times > 1.08 years are estimated. The device is fail-safe against power-cuts of up to 10 hours. This makes our planned comparisons of the fundamental properties of protons and antiprotons independent from accelerator cycles, and will enable us to perform experiments during long accelerator shutdown periods when background magnetic noise is low. The demonstrated scheme has the potential to be applied in many other precision Penning trap experiments dealing with exotic particles.

  8. Energy-dependent partial-wave analysis of all antiproton-proton scattering data below 925 MeV/c

    NARCIS (Netherlands)

    Zhou, Daren; Timmermans, Rob G. E.

    2012-01-01

    Background: There is a renewed experimental interest in antiproton-proton scattering with an intense, possibly polarized antiproton beam. On the theoretical side, significant progress has been made in the understanding of the nuclear force from chiral effective field theory. Purpose: We provide a hi

  9. A silicon multiplicity detector system for an experiment on the interaction of antiprotons with nuclei at BNL

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, S.; Bonner, B.E.; Buchanan, J.A.; Clement, J.M.; Empl, A.; Mutchler, G.S.; Toshkov, S. (Rice Univ., Houston, TX (United States). Bonner Nuclear Labs.); Eiseman, S.E.; Etkin, A.; Foley, K.J.; Hackenburg, R.W.; Longacre, R.S.; Love, W.A.; Morris, T.W.; Platner, E.D.; Saulys, A.C. (Brookhaven National Lab., Upton, NY (United States)); Chan, C.S.; Kramer, M.A.; Lindenbaum, S.J. (City Coll., New York, NY (Unit

    1991-01-01

    A Large Angle Multiplicity Detector (LAMD) system has been developed and used at the BNL experiment E854: Antiproton Nucleus Interactions. This system performed well with an energetic antiproton beam. Charged particle multiplicity distributions from pbar annihilations were measured. We discuss the design and performance of the LAMD system in this paper. 6 refs., 10 figs.

  10. A silicon multiplicity detector system for an experiment on the interaction of antiprotons with nuclei at BNL

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, S.; Bonner, B.E.; Buchanan, J.A.; Clement, J.M.; Empl, A.; Mutchler, G.S.; Toshkov, S. [Rice Univ., Houston, TX (United States). Bonner Nuclear Labs.; Eiseman, S.E.; Etkin, A.; Foley, K.J.; Hackenburg, R.W.; Longacre, R.S.; Love, W.A.; Morris, T.W.; Platner, E.D.; Saulys, A.C. [Brookhaven National Lab., Upton, NY (United States); Chan, C.S.; Kramer, M.A.; Lindenbaum, S.J. [City Coll., New York, NY (United States); Hallman, T.J.; Madansky, L. [Johns Hopkins Univ., Baltimore, MD (United States); Peaslee, D.C. [Maryland Univ., College Park, MD (United States)

    1991-12-31

    A Large Angle Multiplicity Detector (LAMD) system has been developed and used at the BNL experiment E854: Antiproton Nucleus Interactions. This system performed well with an energetic antiproton beam. Charged particle multiplicity distributions from pbar annihilations were measured. We discuss the design and performance of the LAMD system in this paper. 6 refs., 10 figs.

  11. A silicon multiplicity detector system for an experiment on the interaction of antiprotons with nuclei at BNL

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, S.; Bonner, B.E.; Buchanan, J.A.; Clement, J.M.; Empl, A.; Mutchler, G.S.; Toshkov, S. (Rice Univ., Houston, TX (United States). Bonner Nuclear Labs.); Eiseman, S.E.; Etkin, A.; Foley, K.J. (Brookhaven National Lab., Upton, NY (United States))

    1992-08-01

    A Large Angle Multiplicity Detector (LAMD) system has been developed and used at the BNL experiment E854: Antiproton Nucleus Interactions. This system performed well with an energetic antiproton beam. Charged particle multiplicity distributions from [bar p] annihilations were measured. The authors discuss the design and performance of the LAMD system in this paper.

  12. Roos and NACP-02 ion chamber perturbations and water-air stopping-power ratios for clinical electron beams for energies from 4 to 22 MeV.

    Science.gov (United States)

    Bailey, M; Shipley, D R; Manning, J W

    2015-02-07

    Empirical fits are developed for depth-compensated wall- and cavity-replacement perturbations in the PTW Roos 34001 and IBA / Scanditronix NACP-02 parallel-plate ionisation chambers, for electron beam qualities from 4 to 22 MeV for depths up to approximately 1.1 × R₅₀,D. These are based on calculations using the Monte Carlo radiation transport code EGSnrc and its user codes with a full simulation of the linac treatment head modelled using BEAMnrc. These fits are used with calculated restricted stopping-power ratios between air and water to match measured depth-dose distributions in water from an Elekta Synergy clinical linear accelerator at the UK National Physical Laboratory. Results compare well with those from recent publications and from the IPEM 2003 electron beam radiotherapy Code of Practice.

  13. Single-scan scatter correction in CBCT by using projection correlation based view interpolation (PC-VI) and a stationary ring-shaped beam stop array (BSA)

    CERN Document Server

    Yan, Hao; Zhang, Yanbo; Zankl, Maria

    2014-01-01

    In the scatter correction for x-ray Cone Beam (CB) CT, the single-scan scheme with moving Beam Stop Array (BSA) offers reliable scatter measurement with low dose, and by using Projection Correlation based View Interpolation (PC-VI), the primary fluence shaded by the moving BSA (during scatter measurement) could be recovered with high accuracy. However, the moving BSA may increase the mechanical burden in real applications. For better practicability, in this paper we proposed a PC-VI based single-scan scheme with a ring-shaped stationary BSA, which serves as a virtual moving BSA during CB scan, so the shaded primary fluence by this stationary BSA can be also well recovered by PC-VI. The principle in designing the whole system is deduced and evaluated. The proposed scheme greatly enhances the practicability of the single-scan scatter correction scheme.

  14. Comparison of electromagnetic and hadronic models generated using Geant 4 with antiproton dose measured in CERN.

    Science.gov (United States)

    Tavakoli, Mohammad Bagher; Reiazi, Reza; Mohammadi, Mohammad Mehdi; Jabbari, Keyvan

    2015-01-01

    After proposing the idea of antiproton cancer treatment in 1984 many experiments were launched to investigate different aspects of physical and radiobiological properties of antiproton, which came from its annihilation reactions. One of these experiments has been done at the European Organization for Nuclear Research known as CERN using the antiproton decelerator. The ultimate goal of this experiment was to assess the dosimetric and radiobiological properties of beams of antiprotons in order to estimate the suitability of antiprotons for radiotherapy. One difficulty on this way was the unavailability of antiproton beam in CERN for a long time, so the verification of Monte Carlo codes to simulate antiproton depth dose could be useful. Among available simulation codes, Geant4 provides acceptable flexibility and extensibility, which progressively lead to the development of novel Geant4 applications in research domains, especially modeling the biological effects of ionizing radiation at the sub-cellular scale. In this study, the depth dose corresponding to CERN antiproton beam energy by Geant4 recruiting all the standard physics lists currently available and benchmarked for other use cases were calculated. Overall, none of the standard physics lists was able to draw the antiproton percentage depth dose. Although, with some models our results were promising, the Bragg peak level remained as the point of concern for our study. It is concluded that the Bertini model with high precision neutron tracking (QGSP_BERT_HP) is the best to match the experimental data though it is also the slowest model to simulate events among the physics lists.

  15. Comparison of electromagnetic and hadronic models generated using Geant 4 with antiproton dose measured in CERN

    Directory of Open Access Journals (Sweden)

    Mohammad Bagher Tavakoli

    2015-01-01

    Full Text Available After proposing the idea of antiproton cancer treatment in 1984 many experiments were launched to investigate different aspects of physical and radiobiological properties of antiproton, which came from its annihilation reactions. One of these experiments has been done at the European Organization for Nuclear Research known as CERN using the antiproton decelerator. The ultimate goal of this experiment was to assess the dosimetric and radiobiological properties of beams of antiprotons in order to estimate the suitability of antiprotons for radiotherapy. One difficulty on this way was the unavailability of antiproton beam in CERN for a long time, so the verification of Monte Carlo codes to simulate antiproton depth dose could be useful. Among available simulation codes, Geant4 provides acceptable flexibility and extensibility, which progressively lead to the development of novel Geant4 applications in research domains, especially modeling the biological effects of ionizing radiation at the sub-cellular scale. In this study, the depth dose corresponding to CERN antiproton beam energy by Geant4 recruiting all the standard physics lists currently available and benchmarked for other use cases were calculated. Overall, none of the standard physics lists was able to draw the antiproton percentage depth dose. Although, with some models our results were promising, the Bragg peak level remained as the point of concern for our study. It is concluded that the Bertini model with high precision neutron tracking (QGSP_BERT_HP is the best to match the experimental data though it is also the slowest model to simulate events among the physics lists.

  16. Measurement of interaction between antiprotons

    Science.gov (United States)

    The Star Collaboration; Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Alekseev, I.; Alford, J.; Aparin, A.; Arkhipkin, D.; Aschenauer, E. C.; Averichev, G. S.; Bairathi, V.; Banerjee, A.; Bellwied, R.; Bhasin, A.; Bhati, A. K.; Bhattarai, P.; Bielcik, J.; Bielcikova, J.; Bland, L. C.; Bordyuzhin, I. G.; Bouchet, J.; Brandenburg, J. D.; Brandin, A. V.; Bunzarov, I.; Butterworth, J.; Caines, H.; Calderón de La Barca Sánchez, M.; Campbell, J. M.; Cebra, D.; Cervantes, M. C.; Chakaberia, I.; Chaloupka, P.; Chang, Z.; Chattopadhyay, S.; Chen, J. H.; Chen, X.; Cheng, J.; Cherney, M.; Christie, W.; Contin, G.; Crawford, H. J.; Das, S.; de Silva, L. C.; Debbe, R. R.; Dedovich, T. G.; Deng, J.; Derevschikov, A. A.; di Ruzza, B.; Didenko, L.; Dilks, C.; Dong, X.; Drachenberg, J. L.; Draper, J. E.; Du, C. M.; Dunkelberger, L. E.; Dunlop, J. C.; Efimov, L. G.; Engelage, J.; Eppley, G.; Esha, R.; Evdokimov, O.; Eyser, O.; Fatemi, R.; Fazio, S.; Federic, P.; Fedorisin, J.; Feng, Z.; Filip, P.; Fisyak, Y.; Flores, C. E.; Fulek, L.; Gagliardi, C. A.; Garand, D.; Geurts, F.; Gibson, A.; Girard, M.; Greiner, L.; Grosnick, D.; Gunarathne, D. S.; Guo, Y.; Gupta, A.; Gupta, S.; Guryn, W.; Hamad, A.; Hamed, A.; Haque, R.; Harris, J. W.; He, L.; Heppelmann, S.; Heppelmann, S.; Hirsch, A.; Hoffmann, G. W.; Hofman, D. J.; Horvat, S.; Huang, B.; Huang, H. Z.; Huang, X.; Huck, P.; Humanic, T. J.; Igo, G.; Jacobs, W. W.; Jang, H.; Jiang, K.; Judd, E. G.; Kabana, S.; Kalinkin, D.; Kang, K.; Kauder, K.; Ke, H. W.; Keane, D.; Kechechyan, A.; Khan, Z. H.; Kikoła, D. P.; Kisel, I.; Kisiel, A.; Klein, S.; Kochenda, L.; Koetke, D. D.; Kollegger, T.; Kosarzewski, L. K.; Kraishan, A. F.; Kravtsov, P.; Krueger, K.; Kulakov, I.; Kumar, L.; Kycia, R. A.; Lamont, M. A. C.; Landgraf, J. M.; Landry, K. D.; Lauret, J.; Lebedev, A.; Lednicky, R.; Lee, J. H.; Li, X.; Li, Z. M.; Li, Y.; Li, W.; Li, X.; Li, C.; Lisa, M. A.; Liu, F.; Ljubicic, T.; Llope, W. J.; Lomnitz, M.; Longacre, R. S.; Luo, X.; Ma, G. L.; Ma, R.; Ma, Y. G.; Ma, L.; Magdy, N.; Majka, R.; Manion, A.; Margetis, S.; Markert, C.; Masui, H.; Matis, H. S.; McDonald, D.; Meehan, K.; Minaev, N. G.; Mioduszewski, S.; Mishra, D.; Mohanty, B.; Mondal, M. M.; Morozov, D. A.; Mustafa, M. K.; Nandi, B. K.; Nasim, Md.; Nayak, T. K.; Nigmatkulov, G.; Nogach, L. V.; Noh, S. Y.; Novak, J.; Nurushev, S. B.; Odyniec, G.; Ogawa, A.; Oh, K.; Okorokov, V.; Olvitt, D.; Page, B. S.; Pak, R.; Pan, Y. X.; Pandit, Y.; Panebratsev, Y.; Pawlik, B.; Pei, H.; Perkins, C.; Peterson, A.; Pile, P.; Planinic, M.; Pluta, J.; Poljak, N.; Poniatowska, K.; Porter, J.; Posik, M.; Poskanzer, A. M.; Putschke, J.; Qiu, H.; Quintero, A.; Ramachandran, S.; Raniwala, R.; Raniwala, S.; Ray, R. L.; Ritter, H. G.; Roberts, J. B.; Rogachevskiy, O. V.; Romero, J. L.; Roy, A.; Ruan, L.; Rusnak, J.; Rusnakova, O.; Sahoo, N. R.; Sahu, P. K.; Sakrejda, I.; Salur, S.; Sandweiss, J.; Sarkar, A.; Schambach, J.; Scharenberg, R. P.; Schmah, A. M.; Schmidke, W. B.; Schmitz, N.; Seger, J.; Seyboth, P.; Shah, N.; Shahaliev, E.; Shanmuganathan, P. V.; Shao, M.; Sharma, M. K.; Sharma, B.; Shen, W. Q.; Shi, S. S.; Shou, Q. Y.; Sichtermann, E. P.; Sikora, R.; Simko, M.; Skoby, M. J.; Smirnov, N.; Smirnov, D.; Song, L.; Sorensen, P.; Spinka, H. M.; Srivastava, B.; Stanislaus, T. D. S.; Stepanov, M.; Stock, R.; Strikhanov, M.; Stringfellow, B.; Sumbera, M.; Summa, B.; Sun, Z.; Sun, X. M.; Sun, Y.; Sun, X.; Surrow, B.; Svirida, N.; Szelezniak, M. A.; Tang, Z.; Tang, A. H.; Tarnowsky, T.; Tawfik, A.; Thomas, J. H.; Timmins, A. R.; Tlusty, D.; Tokarev, M.; Trentalange, S.; Tribble, R. E.; Tribedy, P.; Tripathy, S. K.; Trzeciak, B. A.; Tsai, O. D.; Ullrich, T.; Underwood, D. G.; Upsal, I.; van Buren, G.; van Nieuwenhuizen, G.; Vandenbroucke, M.; Varma, R.; Vasiliev, A. N.; Vertesi, R.; Videbæk, F.; Viyogi, Y. P.; Vokal, S.; Voloshin, S. A.; Vossen, A.; Wang, G.; Wang, H.; Wang, J. S.; Wang, Y.; Wang, Y.; Wang, F.; Webb, J. C.; Webb, G.; Wen, L.; Westfall, G. D.; Wieman, H.; Wissink, S. W.; Witt, R.; Wu, Y. F.; Xiao, Z. G.; Xie, W.; Xin, K.; Xu, Y. F.; Xu, Q. H.; Xu, H.; Xu, N.; Xu, Z.; Yang, Y.; Yang, C.; Yang, S.; Yang, Y.; Yang, Q.; Ye, Z.; Yepes, P.; Yi, L.; Yip, K.; Yoo, I.-K.; Yu, N.; Zbroszczyk, H.; Zha, W.; Zhang, J. B.; Zhang, Z.; Zhang, J.; Zhang, S.; Zhang, X. P.; Zhang, J.; Zhang, Y.; Zhao, J.; Zhong, C.; Zhou, L.; Zhu, X.; Zoulkarneeva, Y.; Zyzak, M.

    2015-11-01

    One of the primary goals of nuclear physics is to understand the force between nucleons, which is a necessary step for understanding the structure of nuclei and how nuclei interact with each other. Rutherford discovered the atomic nucleus in 1911, and the large body of knowledge about the nuclear force that has since been acquired was derived from studies made on nucleons or nuclei. Although antinuclei up to antihelium-4 have been discovered and their masses measured, little is known directly about the nuclear force between antinucleons. Here, we study antiproton pair correlations among data collected by the STAR experiment at the Relativistic Heavy Ion Collider (RHIC), where gold ions are collided with a centre-of-mass energy of 200 gigaelectronvolts per nucleon pair. Antiprotons are abundantly produced in such collisions, thus making it feasible to study details of the antiproton-antiproton interaction. By applying a technique similar to Hanbury Brown and Twiss intensity interferometry, we show that the force between two antiprotons is attractive. In addition, we report two key parameters that characterize the corresponding strong interaction: the scattering length and the effective range of the interaction. Our measured parameters are consistent within errors with the corresponding values for proton-proton interactions. Our results provide direct information on the interaction between two antiprotons, one of the simplest systems of antinucleons, and so are fundamental to understanding the structure of more-complex antinuclei and their properties.

  17. Experiments on Antiprotons: Antiproton-Nucleon Cross Sections

    Science.gov (United States)

    Chamberlain, Owen; Keller, Donald V.; Mermond, Ronald; Segre, Emilio; Steiner, Herbert M.; Ypsilantis, Tom

    1957-07-22

    In this paper experiments are reported on annihilation and scattering of antiprotons in H{sub 2}O , D{sub 2}O, and O{sub 2}. From the data measured it is possible to obtain an antiproton-proton and an antiproton-deuteron cross section at 457 Mev (lab). Further analysis gives the p-p and p-n cross sections as 104 mb for the p-p reaction cross section and 113 mb for the p-n reaction cross section. The respective annihilation cross sections are 89 and 74 mb. The Glauber correction necessary in order to pass from the p-d to the p-n cross section by subtraction of the p-p cross section is unfortunately large and somewhat uncertain. The data are compared with the p-p and p-n cross sections and with other results on p-p collisions.

  18. Laser Spectroscopy of Antiprotonic Helium Atoms

    CERN Multimedia

    2002-01-01

    %PS205 %title\\\\ \\\\Following the discovery of metastable antiprotonic helium atoms ($\\overline{p}He^{+} $) at KEK in 1991, systematic studies of their properties were made at LEAR from 1991 to 1996. In the first two years the lifetime of $\\overline{p}He^{+}$ in liquid and gaseous helium at various temperatures and pressures was measured and the effect of foreign gases on the lifetime of these atoms was investigated. Effects were also discovered which gave the antiproton a 14\\% longer lifetime in $^4$He than in $^3$He, and resulted in important differences in the shape of the annihilation time spectra in the two isotopes.\\\\ \\\\Since 1993 laser spectroscopy of the metastable $\\overline{p}He^{+}$ atoms became the main focus of PS205. Transitions were stimulated between metastable and non-metastable states of the $\\overline{p}He^{+}$ atom by firing a pulsed dye laser beam into the helium target every time an identified metastable atom was present (Figure 1). If the laser frequency matched the transition energy, the...

  19. Compression of Antiproton Clouds for Antihydrogen Trapping

    CERN Document Server

    Andresen, G B; Bowe, P D; Bray, C C; Butler, E; Cesar, C L; Chapman, S; Charlton, M; Fajans, J; Fujiwara, M C; Funakoshi, R; Gill, D R; Hangst, J S; Hardy, W N; Hayano, R S; Hayden, M E; Hydomako, R; Jenkins, M J; Jørgensen, L V; Kurchaninov, L; Lambo, R; Madsen, N; Nolan, P; Olchanski, K; Olin, A; Povilus, A; Pusa, P; Robicheaux, F; Sarid, E; Seif El Nasr, S; Silveira, D M; Storey, J W; Thompson, R I; Van der Werf, D P; Wurtele, J S; Yamazaki, Y

    2008-01-01

    Control of the radial profile of trapped antiproton clouds is critical to trapping antihydrogen. We report the first detailed measurements of the radial manipulation of antiproton clouds, including areal density compressions by factors as large as ten, by manipulating spatially overlapped electron plasmas. We show detailed measurements of the near-axis antiproton radial profile and its relation to that of the electron plasma.

  20. A practical scattering power for Gaussian beam model of heavy charged particles stopping in tissue-like matter

    CERN Document Server

    Kanematsu, Nobuyuki

    2008-01-01

    Dose calculation in treatment planning of radiotherapy with protons and heavier ions deals with a large volume of path integrals involving a scattering power of body tissue. This work provides a simple formulation for such demanding applications. Empirical linearity between RMS end-point displacement and range of incident particles in water was translated into a linear formula, from which a simple scattering power was derived. The simplicity enabled analytical formulation for ions stopping in water, which was designed to be equivalent with the extended Highland model and agreed with measurements better than 2% or 0.02 cm in RMS displacement. The simplicity will also improve the efficiency of numerical path integrals in the presence of heterogeneity.

  1. The CERN Antiproton Collider Programme Accelerators and Accumulation Rings

    CERN Document Server

    Koziol, Heribert

    2004-01-01

    One of CERN's most daring and successful undertakings was the quest for the intermediate bosons, W and Z. In this paper, we describe the accelerator part of the venture which relied on a number of innovations: an extension of the budding method of stochastic cooling by many orders of magnitude; the construction of the Antiproton Accumulator, depending on several novel accelerator methods and technologies; major modifications to the 26 GeV PS Complex; and the radical conversion of the 300 GeV SPS, which just had started up as an accelerator, to a protonâ€"antiproton collider. The SPS Collider had to master the beamâ€"beam effect far beyond limits reached ever before and had to function in a tight symbiosis with the huge detectors UA1 and UA2.

  2. Thick-target neutron, gamma-ray, and radionuclide production for protons below 12 MeV on nickel and carbon beam-stops

    Energy Technology Data Exchange (ETDEWEB)

    Chadwick, M.B.; Young, P.G.; Wilson, W.B.

    1998-03-01

    Nuclear model calculations using the GNASH code are described for protons below 12 MeV incident on nickel and carbon isotopes, for beam stop design in the Los Alamos Accelerator Production of Tritium Low Energy Demonstration Accelerator (LEDA) project. The GNASH calculations apply Hauser-Feshbach and preequilibrium reaction theories and can make use of pre-calculated direct reaction cross sections to low-lying residual nucleus states. From calculated thin target cross sections, thick target 6.7 MeV and 12 MeV proton-induced production of neutrons, gamma rays, and radionuclides are determined. Emission spectra of the secondary neutrons and gamma rays are also determined. The model calculations are validated through comparisons with experimental thin- and thick-target measurements. The results of this work are being utilized as source terms in MCNP analyses for LEDA.

  3. Nuclear dynamics induced by antiprotons

    CERN Document Server

    Feng, Zhao-Qing

    2015-01-01

    Reaction dynamics in collisions of antiprotons on nuclei is investigated within the Lanzhou quantum molecular dynamics model. The reaction channels of elastic scattering, annihilation, charge exchange and inelastic collisions of antiprotons on nucleons have been included in the model. Dynamics on particle production, in particular pions, kaons, antikaons and hyperons, is investigated in collisions of $\\overline{p}$ on $^{12}$C, $^{20}$Ne, $^{40}$Ca and $^{181}$Ta from a low to high incident momenta. It is found that the annihilations of $\\overline{p}$ on nucleons are of importance on the dynamics of particle production in phase space. Hyperons are mainly produced via meson induced reactions on nucleons and strangeness exchange collisions, which lead to the delayed emission in antiproton-nucleus collisions.

  4. Enhancing trappable antiproton populations through deceleration and frictional cooling

    Energy Technology Data Exchange (ETDEWEB)

    Zolotorev, Max; Sessler, Andrew; Penn, Gregory; Wurtele, Jonathan S.; Charman, Andrew E.

    2012-03-20

    CERN currently delivers antiprotons for trapping experiments with the Antiproton Decelerator (AD), which slows the antiprotons down to about 5 MeV.This energy is currently too high for direct trapping, and thick foils are used to slow down the beam to energies which can be trapped.To allow further deceleration to $\\sim 100 \\;\\mbox{keV}$, CERN is initiating the construction of ELENA,consisting of a ring which will combine RF deceleration and electron cooling capabilities. We describe a simple frictionalcooling scheme that can serve to provide significantly improved trapping efficiency, either directly from the AD or first usinga standard deceleration mechanism (induction linac or RFQ). This scheme could be implemented in a short time.The device itself is short in length, uses accessible voltages, and at reasonable cost could serve in the interim beforeELENA becomes operational, or possibly in lieu of ELENA for some experiments. Simple theory and simulations provide a preliminary assessment of theconcept and its strengths and limitations, and highlight important areas for experimental studies, in particular to pin down the level of multiplescattering for low-energy antiprotons. We show that the frictional cooling scheme can provide a similar energy spectrum to that of ELENA,but with higher transverse emittances.

  5. Antiproton collisions with molecular hydrogen

    DEFF Research Database (Denmark)

    Lühr, Armin Christian; Saenz, Alejandro

    2008-01-01

    Theoretical antiproton and proton cross sections for ionization and excitation of hydrogen molecules as well as energy spectra of the ionized electrons were calculated in the impact-energy range from 8  to  4000  keV. The cross sections were computed with the close-coupling formulation of the sem......Theoretical antiproton and proton cross sections for ionization and excitation of hydrogen molecules as well as energy spectra of the ionized electrons were calculated in the impact-energy range from 8  to  4000  keV. The cross sections were computed with the close-coupling formulation...

  6. Electronic stopping power in LiF from first principles.

    Science.gov (United States)

    Pruneda, J M; Sánchez-Portal, D; Arnau, A; Juaristi, J I; Artacho, Emilio

    2007-12-07

    Using time-dependent density-functional theory we calculate from first principles the rate of energy transfer from a moving proton or antiproton to the electrons of an insulating material, LiF. The behavior of the electronic stopping power versus projectile velocity displays an effective threshold velocity of approximately 0.2 a.u. for the proton, consistent with recent experimental observations, and also for the antiproton. The calculated proton/antiproton stopping-power ratio is approximately 2.4 at velocities slightly above the threshold (v approximately 0.4 a.u.), as compared to the experimental value of 2.1. The projectile energy loss mechanism is observed to be extremely local.

  7. LEAR (Low Energy Antiproton Ring), general view.

    CERN Multimedia

    1990-01-01

    When the Antiproton Project was launched in the late 1970s, it was recognized that in addition to the primary purpose of high-energy proton-antiproton collisions in the SPS, there was interesting physics to be done with low-energy antiprotons. In 1982, LEAR was ready to receive antiprotons from the Antiproton Accumulator (AA), via the PS. A year later, delivery of antiprotons to the experiments began, at momenta as low as 100 MeV/c (kinetic energy 5.3 MeV), in an "Ultra-Slow Extraction" mode, dispensing some E9 antiprotons over times counted in hours. For such an achievement, stochastic and electron cooling had to be brought to high levels of perfection.

  8. Physics at CERN's Antiproton Decelerator

    CERN Document Server

    Hori, M

    2013-01-01

    The Antiproton Decelerator of CERN began operation in 1999 to serve experiments for studies of CPT invariance by precision laser and microwave spectroscopy of antihydrogen ($\\bar{\\rm H}$) and antiprotonic helium ($\\bar{p}{\\rm He}^+$). The first 12 years of operation saw cold $\\bar{\\rm H}$ synthesized by overlapping clouds of positrons ($e^+$) and antiprotons ($\\bar{p}$) confined in magnetic Penning traps. Cold $\\bar{\\rm H}$ was also produced in collisions between Rydberg positronium atoms and $\\bar{p}$. Ground-state $\\bar{\\rm H}$ was later trapped for up to $\\sim 1000$ s in a magnetic bottle trap, and microwave transitions excited between its hyperfine levels. In the $\\bar{p}{\\rm He}^+$ atom, UV transitions were measured to a precision of (2.3-5) $\\times$ $10^{-9}$ by sub-Doppler two-photon laser spectroscopy. From this the antiproton-to-electron mass ratio was determined as $M_{\\bar{p}}/m_e=$1836.1526736(23), which agrees with the p value. Microwave spectroscopy of $\\bar{p}{\\rm He}^+$ yielded a measurement o...

  9. Stop Ticks

    Science.gov (United States)

    ... this? Submit Button Past Emails CDC Features Stop Ticks Language: English Español (Spanish) Recommend on Facebook Tweet ... What to Do if You Find an Attached Tick Remove the attached tick as soon as you ...

  10. New stopping cell capabilities : RF carpet performance at high gas density and cryogenic operation

    NARCIS (Netherlands)

    Ranjan, M.; Purushothaman, S.; Dickel, T.; Geissel, H.; Plass, W. R.; Schaefer, D.; Scheidenberger, C.; Van de Walle, J.; Weick, H.; Dendooven, P.

    2011-01-01

    We have developed a stopping cell to be used at the FRS and Super-FRS (Superconducting FRagment Separator) at the GSI Helmholtz Centre for Heavy-Ion Research and the Facility for Antiproton and Ion Research (FAIR), both in Darmstadt, Germany. The cell has a stopping volume with a length of 1m and a

  11. The FRS Ion Catcher - A facility for high-precision experiments with stopped projectile and fission fragments

    Science.gov (United States)

    Plaß, W. R.; Dickel, T.; Purushothaman, S.; Dendooven, P.; Geissel, H.; Ebert, J.; Haettner, E.; Jesch, C.; Ranjan, M.; Reiter, M. P.; Weick, H.; Amjad, F.; Ayet, S.; Diwisch, M.; Estrade, A.; Farinon, F.; Greiner, F.; Kalantar-Nayestanaki, N.; Knöbel, R.; Kurcewicz, J.; Lang, J.; Moore, I.; Mukha, I.; Nociforo, C.; Petrick, M.; Pfützner, M.; Pietri, S.; Prochazka, A.; Rink, A.-K.; Rinta-Antila, S.; Schäfer, D.; Scheidenberger, C.; Takechi, M.; Tanaka, Y. K.; Winfield, J. S.; Yavor, M. I.

    2013-12-01

    At the FRS Ion Catcher at GSI, projectile and fission fragments are produced at relativistic energies, separated in-flight, range-focused, slowed down and thermalized in a cryogenic stopping cell. A multiple-reflection time-of-flight mass spectrometer (MR-TOF-MS) is used to perform direct mass measurements and to provide an isobarically clean beam for further experiments, such as mass-selected decay spectroscopy. A versatile RF quadrupole transport and diagnostics unit guides the ions from the stopping cell to the MR-TOF-MS, provides differential pumping, ion identification and includes reference ion sources. The FRS Ion Catcher serves as a test facility for the Low-Energy Branch of the Super-FRS at the Facility for Antiproton and Ion Research (FAIR), where the cryogenic stopping cell and the MR-TOF-MS will be key devices for the research with stopped projectile and fission fragments that will be performed with the experiments MATS and LaSpec. Off-line tests of the stopping cell yield a combined ion survival and extraction efficiency for 219Rn ions of about 30% and an extraction time of about 25 ms. The stopping cell and the MR-TOF-MS were commissioned on-line as part of the FRS Ion Catcher. For the first time, a stopping cell for exotic nuclei was operated on-line at cryogenic temperatures. Using a gas density almost two times higher than ever reached before for a stopping cell with RF ion repelling structures, various 238U projectile fragments were thermalized and extracted with very high efficiency. Direct mass measurements of projectile fragments were performed with the MR-TOF-MS, among them the nuclide 213Rn with a half-life of 19.5 ms only.

  12. Cosmic ray antiprotons at high energies

    Science.gov (United States)

    Winkler, Martin Wolfgang

    2017-02-01

    Cosmic ray antiprotons provide a powerful tool to probe dark matter annihilations in our galaxy. The sensitivity of this important channel is, however, diluted by sizable uncertainties in the secondary antiproton background. In this work, we improve the calculation of secondary antiproton production with a particular focus on the high energy regime. We employ the most recent collider data and identify a substantial increase of antiproton cross sections with energy. This increase is driven by the violation of Feynman scaling as well as by an enhanced strange hyperon production. The updated antiproton production cross sections are made publicly available for independent use in cosmic ray studies. In addition, we provide the correlation matrix of cross section uncertainties for the AMS-02 experiment. At high energies, the new cross sections improve the compatibility of the AMS-02 data with a pure secondary origin of antiprotons in cosmic rays.

  13. PS, septum magnet for ejection of antiprotons

    CERN Multimedia

    1980-01-01

    Antiprotons circulated in the PS in the sense opposite to that of the so far normal protons (or positive ions). A new ejection system with a new septum magnet was installed in straight section 58 for antiproton ejection, first towards the ISR and then to the principal customer, the SPS p-pbar Collider. Later on, when the PS delivered leptons for LEP, the antiproton ejection system was use for the ejection of electrons.

  14. On Antiproton Production in 158 GeV/c Proton-Carbon Collisions and Nuclear Temperature of Interacting System

    Directory of Open Access Journals (Sweden)

    Fu-Hu Liu

    2013-01-01

    Full Text Available The multisource thermal model is used in this paper to analyze the antiproton (p¯ production process in high-energy proton-carbon (p-C collisions. The transverse momentum, Feynman variable, and rapidity distributions of antiprotons in the nucleon-nucleon center-of-mass system are calculated by using the model. The modeling results are compared and found to be in agreement with the experimental data measured by the NA49 Collaboration at 158 GeV/c beam momentum. As a parameter, the nuclear temperature of interacting system extracted from the antiproton spectrum is estimated to be about 150 MeV.

  15. Influence of the delta ray production threshold on water-to-air stopping power ratio calculations for carbon ion beam radiotherapy.

    Science.gov (United States)

    Sánchez-Parcerisa, D; Gemmel, A; Jäkel, O; Rietzel, E; Parodi, K

    2013-01-07

    Previous calculations of the water-to-air stopping power ratio (s(w,)(air)) for carbon ion beams did not involve tracking of delta ray electrons, even though previous calculations with protons predict an effect up to 1%. We investigate the effect of the delta ray production threshold in s(w,)(air) calculations and propose an empirical expression which takes into account the effect of the delta ray threshold as well as the uncertainty in the mean ionization potentials (I-values) of air and water. The formula is derived from the results of Monte Carlo calculations using the most up-to-date experimental data for I-values and a delta ray production threshold of 10 keV. It allows us to reduce the standard uncertainty in s(w,)(air) below 0.8%, instead of the current 2% given in international protocols, which results in a reduction of the overall uncertainty for absolute dosimetry based on air-filled ionization chambers.

  16. On the Utility of Antiprotons as Drivers for Inertial Confinement Fusion

    Energy Technology Data Exchange (ETDEWEB)

    Perkins, L J; Orth, C D; Tabak, M

    2003-10-20

    By contrast to the large mass, complexity and recirculating power of conventional drivers for inertial confinement fusion (ICF), antiproton annihilation offers a specific energy of 90MJ/{micro}g and thus a unique form of energy packaging and delivery. In principle, antiproton drivers could provide a profound reduction in system mass for advanced space propulsion by ICF. We examine the physics underlying the use of antiprotons ({bar p}) to drive various classes of high-yield ICF targets by the methods of volumetric ignition, hotspot ignition and fast ignition. The useable fraction of annihilation deposition energy is determined for both {bar p}-driven ablative compression and {bar p}-driven fast ignition, in association with 0-D and 1-D target burn models. Thereby, we deduce scaling laws for the number of injected antiprotons required per capsule, together with timing and focal spot requirements. The kinetic energy of the injected antiproton beam required to penetrate to the desired annihilation point is always small relative to the deposited annihilation energy. We show that heavy metal seeding of the fuel and/or ablator is required to optimize local deposition of annihilation energy and determine that a minimum of {approx}3x10{sup 15} injected antiprotons will be required to achieve high yield (several hundred megajoules) in any target configuration. Target gains - i.e., fusion yields divided by the available p - {bar p} annihilation energy from the injected antiprotons (1.88GeV/{bar p}) - range from {approx}3 for volumetric ignition targets to {approx}600 for fast ignition targets. Antiproton-driven ICF is a speculative concept, and the handling of antiprotons and their required injection precision - temporally and spatially - will present significant technical challenges. The storage and manipulation of low-energy antiprotons, particularly in the form of antihydrogen, is a science in its infancy and a large scale-up of antiproton production over present supply

  17. Compression and extraction of stopped muons.

    Science.gov (United States)

    Taqqu, D

    2006-11-10

    Efficient conversion of a standard positive muon beam into a high-quality slow muon beam is shown to be achievable by compression of a muon swarm stopped in an extended gas volume. The stopped swarm can be squeezed into a mm-size swarm flow that can be extracted into vacuum through a small opening in the stop target walls. Novel techniques of swarm compression are considered. In particular, a density gradient in crossed electric and magnetic fields is used.

  18. The low energy atmospheric antiproton albedo

    Science.gov (United States)

    Cole, J. B.; Ormes, J. F.

    1989-01-01

    The flux of albedo antiprotons in the 100-1000 MeV kinetic energy range produced by the cosmic ray primaries in the atmosphere is calculated. It is shown that this is not a significant background to measurements of the low energy anti-proton cosmic ray flux.

  19. Relative Biological Effect of Antiprotons

    DEFF Research Database (Denmark)

    Bassler, Niels; Holzscheiter, Michael

    nuclear research facility CERN. A beam of 126 MeV antiprotons, corresponding to about 12 cm range in water, was spread out to a SOBP with a width of 1 cm. Dosimetry experiments were carried out with ionization chambers, alanine pellets and radiochromic film, and the results were used for benchmarking...

  20. S142 set-up to detect X-ray from antiproton-proton atoms (protonium).

    CERN Multimedia

    1978-01-01

    This experiment was designed by the Daresbury-Mainz-TRIUMF Collaboration and was located in the m14 partially separated antiproton beam in the PS South Hall. It used a gaseous hydrogen target, 1 m long, surrounded by a ring of proportional counters, surrounded in turn by a ring of 36 scintillators strips to aid in the annihilation product identification. Ugo Gastaldi (centre)

  1. Antiproton-nucleus interactions at 5 to 9 GeV/c

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, S. (T.W. Bonner Nuclear Lab., Rice Univ., Houston, TX (United States)); Bonner, B.E. (T.W. Bonner Nuclear Lab., Rice Univ., Houston, TX (United States)); Buchanan, J.A. (T.W. Bonner Nuclear Lab., Rice Univ., Houston, TX (United States)); Chan, C.S. (City Coll. of New York, NY (United States)); Clement, J.M. (T.W. Bonner Nuclear Lab., Rice Univ., Houston, TX (United States)); Eiseman, S.E. (Brookhaven National Lab., Upton, NY (United States)); Empl, A. (T.W. Bonner Nuclear Lab., Rice Univ., Houston, TX (United States)); Etkin, A. (Brookhaven National Lab., Upton, NY (United States)); Foley, K.J. (Brookhaven National Lab., Upton, NY (United States)); Hackenburg, R.W. (Brookhaven National Lab., Upton, NY (United States)); Hallman, T.J. (Johns Hopkins Univ., Baltimore, MD (United States)); Kramer, M.A. (City Coll. of New York, NY (United States)); Kruk, J. (T.W. Bonner Nuclear Lab., Rice Univ., Houston, TX (United States)); Lindenbaum, S.J. (City Coll. of New York, NY (; E854 Collaboration

    1993-06-07

    Antiproton beams of 5, 7 and 9 GeV/c were used to interact with C, Al, Cu, Sn and Pb nuclear targets. Charged particle multiplicity distributions, strange particle production cross sections and rapidity distributions were measured. The charged particle multiplicities are reported in this paper. (orig.)

  2. That was LEAP 05! or Antiproton Physics in a Nutshell

    Science.gov (United States)

    Kienle, Paul

    2005-10-01

    A personally flavored review of selected topics of LEAP 05 is given, with focus on some recent interesting developments in low and medium energy antiproton physics, such as fundamental symmetries and antihydrogen, antihadron-hadron systems, antiproton-proton annihilation, nuclear structure studies with antiprotons, and the FAIR facility for antiproton and ion research.

  3. Neutron fluence in antiproton radiotherapy, measurements and simulations

    DEFF Research Database (Denmark)

    Bassler, Niels; Holzscheiter, Michael H.; Petersen, Jørgen B.B.

    2010-01-01

    A significant part of the secondary particle spectrum from antiproton annihilation consists of fast neutrons, which may contribute to a significant dose background found outside the primary beam. Using a polystyrene phantom as a moderator, we have performed absolute measurements of the thermalized...... part of the fast neutron spectrum using Lithium-6 and -7 Fluoride TLD pairs. The experimental results are found to be in good agreement with simulations using the Monte Carlo particle transport code FLUKA. The thermal neutron kerma resulting from the measured thermal neutron fluence is insignificant...

  4. Antiproton annihilation physics annihilation physics in the Monte Carlo particle transport code particle transport code SHIELD-HIT12A

    DEFF Research Database (Denmark)

    Taasti, Vicki Trier; Knudsen, Helge; Holzscheiter, Michael

    2015-01-01

    The Monte Carlo particle transport code SHIELD-HIT12A is designed to simulate therapeutic beams for cancer radiotherapy with fast ions. SHIELD-HIT12A allows creation of antiproton beam kernels for the treatment planning system TRiP98, but first it must be benchmarked against experimental data...

  5. Operating Procedure Changes to Improve Antiproton Production at the Fermilab Tevatron Collider

    Energy Technology Data Exchange (ETDEWEB)

    Drendel, B.; Morgan, J.P.; Vander Meulen, D.; /Fermilab

    2009-04-01

    Since the start of Fermilab Collider Run II in 2001, the maximum weekly antiproton accumulation rate has increased from 400 x 10{sup 10} Pbars/week to approximately 3,700 x 10{sup 10} Pbars/week. There are many factors contributing to this increase, one of which involves changes to operational procedures that have streamlined and automated Antiproton Source production. Automation has been added to the beam line orbit control, stochastic cooling power level management, and RF settings. In addition, daily tuning efforts have been streamlined by implementing sequencer driven tuning software.

  6. Baryon stopping and charged particle production from lead-lead collisions at 158 GeV per nucleon

    Energy Technology Data Exchange (ETDEWEB)

    Toy, Milton Y. [Univ. of California, Los Angeles, CA (United States)

    1999-01-01

    Net proton (proton minus antiproton) and negative charge hadron spectra (h-) from central Pb+Pb collisions at 158 GeV per nucleon at the CERN Super Proton Synchrotron were measured and compared to spectra from central collisions of the lighter S+S system. Net baryon distributions were derived from those of net protons and net lambdas. Stopping, or rapidity shift with respect to the beam, of net protons and net baryons increase with system size. The mean transverse momentum of net protons also increase with system size. The h- rapidity density scales with the number of participant nucleons for nuclear collisions, where their is independent of system size. The dependence upon particle mass and system size is consistent with larger transverse flow velocity at midrapidity for central collisions of Pb+Pb compared to that of S+S.

  7. Fermilab Antiproton Source, Recycler Ring, and Main Injector

    CERN Document Server

    Nagaitsev, Sergei

    2014-01-01

    At the end of its operations in 2011, the Fermilab antiproton production complex consisted of a sophisticated target system, three 8-GeV storage rings (namely the Debuncher, the Accumulator and the Recycler), 25 independent multi-GHz stochastic cooling systems, the world's only relativistic electron cooling system and a team of technical experts equal to none. The accelerator complex at Fermilab supported a broad physics program including the Tevatron Collider Run II, neutrino experiments using 8-GeV and 120-GeV proton beams, as well as a test beam facility and other fixed target experiments using 120-GeV primary proton beams. This paper provides a brief description of Fermilab accelerators as they operated at the end of the Collider Run II (2011).

  8. Instrumentation for measurement of in-flight annihilations of 130 keV antiprotons on thin target foils

    Science.gov (United States)

    Todoroki, K.; Barna, D.; Hayano, R. S.; Aghai-Khozani, H.; Sótér, A.; Corradini, M.; Leali, M.; Lodi-Rizzini, E.; Mascagna, V.; Venturelli, L.; Prest, V.; Vallazza, L.; De Salvador, D.; Hori, M.

    2016-11-01

    We describe the instrumentation for an experiment to measure the cross sections of antiprotons with kinetic energies of 130±10 keV annihilating on carbon, palladium, and platinum target foils of sub-100 nm thicknesses. A 120 ns long pulsed beam containing 105 -106 antiprotons was allowed to traverse the foils, and the signal annihilations that resulted from this were isolated using a time-of-flight method. Backgrounds arose from Rutherford scattering of the antiprotons off the target foils, their annihilations in the target chamber walls, and π → μ → e decay of the charged pions that emerged from the annihilations. Some antiprotons slowed down and annihilated in the contamination on the target surfaces. This reduced the signal-to-background ratio of the measurement.

  9. Antiproton--Proton Scattering Experiments with Polarization

    CERN Document Server

    Lenisa, P; Lenisa, Paolo; Rathmann, Frank

    2005-01-01

    The document describes the physics case of the PAX experiment using polarized antiprotons, which has recently been proposed for the new Facility for Antiprotons and Ions Research (FAIR) at GSI--Darmstadt. Polarized antiprotons provide access to a wealth of single-- and double--spin observables, thereby opening a new window to physics uniquely accessible at the HESR. The polarized antiprotons would be most efficiently produced by spin--filtering in a dedicated Antiproton Polarizer Ring (APR) using an internal polarized hydrogen gas target. In the proposed collider scenario of the PAX experiment, polarized protons stored in a COSY--like Cooler Storage Ring (CSR) up to momenta of 3.5 GeV/c are bombarded head--on with 15 GeV/c polarized antiprotons stored in the HESR. This asymmetric double--polarized antiproton--proton collider is ideally suited to map, e.g., the transversity distribution in the proton. The proposed detector consists of a large--angle apparatus optimized for the detection of Drell--Yan electron ...

  10. High-precision spectroscopy of antiprotonic helium

    CERN Document Server

    Widmann, E

    2001-01-01

    We present first results of laser and microwave spectroscopy experiments of antiprotonic helium performed at the new Antiproton Decelerator (AD) at CERN. Extending a series of previous measurements done at the Low Energy Antiproton Ring (LEAR) of CERN, several laser- induced transitions of the antiproton in the exotic three-body system He/sup 2+/-e/sup -/-p could be determined with a precision down to 1.3*10/sup -7/. This constitutes an improvement of a factor 3 over previous measurements, and allows to test accurate three-body calculations of this system that include QED corrections. The observed agreement on the same level can be used to infer CPT limits on the antiproton charge and mass. Furthermore, a first indication of a resonance signal of a two-laser microwave triple experiment to measure the hyperfine splitting of antiprotonic helium could been observed. Such a measurement has the potential to determine the antiproton magnetic moment to a higher precision that it is known today. (19 refs).

  11. A detector to search for antiproton decay at the Fermilab antiproton accumulator

    Energy Technology Data Exchange (ETDEWEB)

    Armstrong, T. [Pennsylvania State Univ., University Park, PA (United States); Buchanan, C.; Corbin, B.; Lindgren, M.; Muller, T.; Scott, A. [University of California at Los Angeles, Los Angeles, CA 90024 (United States); Geer, S.; Marriner, J.; Martens, M.; Ray, R.; Streets, J.; Wester, W. [Fermi National Accelerator Laboratory, Batavia, IL 60510 (United States); Gustafson, R. [University of Michigan, Ann Arbor, MI 48109 (United States); Hu, M.; Snow, G.R. [University of Nebraska-Lincoln, Lincoln, NE (United States); APEX Collaboration

    1998-07-11

    We describe the experimental apparatus used by the APEX experiment (Experiment 868) at the Fermilab antiproton accumulator. The experiment is designed to search for decays of 8.9 GeV/c antiprotons as they traverse a 3.7 m long evacuated decay tank inserted in a straight section of the antiproton accumulator ring. The detector components in the experimental set-up are discussed individually, and the performance of the experiment during data-taking is described. (orig.)

  12. Measurement of the Antiprotonic Lyman- and Balmer X-rays of $\\overline{p}H$ and $\\overline{p}D$ Atoms at Very Low Target Pressures

    CERN Multimedia

    2002-01-01

    The aim of this experiment is to measure the energies and intensities of the n @A 1 (Lyman) and n @A 2 (Balmer) tansitions with high accuracy in both @*H and @*D, from which the strong interaction effects of the 1s- and 2p-level can be extracted. These observables may be related to the antiproton-proton and antiproton-neutron scattering length. \\\\ \\\\ Since in these targets collisional Stark effect occurs, we will stop the antiprotons in extreme thin gaseous targets (pressure as low as 10 Torr), where no Stark effect occurs and the 2-1 transition is favoured. In order to use antiprotons with high efficiency despite of the low target density, we will trap antiprotons of a momentum of 100 MeV/c in a magnetic field of cyclotron characteristics. The antiprotons are decelerated by their energy loss in the target gas. The focusing properties of the magnetic field serve to compensate the multiple scattering and we will end up with a concentrated stopping distribution at the centre. Due to the long orbiting time, back...

  13. Prospects for Antiproton Experiments at Fermilab

    CERN Document Server

    Kaplan, Daniel M

    2011-01-01

    Fermilab operates the world's most intense antiproton source. Newly proposed experiments can use those antiprotons either parasitically during Tevatron Collider running or after the end of the Tevatron Collider program. For example, the annihilation of 5 to 8 GeV antiprotons is expected to yield world-leading sensitivities to hyperon rare decays and CP violation. It could also provide the world's most intense source of tagged D^0 mesons, and thus the best near-term opportunity to study charm mixing and, via CP violation, to search for new physics. Other measurements that could be made include properties of the X(3872) and the charmonium system. An experiment using a Penning trap and an atom interferometer could make the world's most precise measurement of the gravitational force on antimatter. These and other potential measurements using antiprotons offer a great opportunity for a broad and exciting physics program at Fermilab in the post-Tevatron era.

  14. Antiproton Induced Fission and Fragmentation of Nuclei

    CERN Multimedia

    2002-01-01

    The annihilation of slow antiprotons with nuclei results in a large highly localized energy deposition primarily on the nuclear surface. \\\\ \\\\ The study of antiproton induced fission and fragmentation processes is expected to yield new information on special nuclear matter states, unexplored fission modes, multifragmentation of nuclei, and intranuclear cascades.\\\\ \\\\ In order to investigate the antiproton-nucleus interaction and the processes following the antiproton annihilation at the nucleus, we propose the following experiments: \\item A)~Measurement of several fragments from fission and from multifragmentation in coincidence with particle spectra, especially neutrons and kaons. \\item B)~Precise spectra of $\\pi$, K, n, p, d and t with time-of-flight techniques. \\item C)~Installation of the Berlin 4$\\pi$ neutron detector with a 4$\\pi$ Si detector placed inside for fragments and charged particles. This yields neutron multiplicity distributions and consequently distributions of thermal excitation energies and...

  15. D¯ D meson pair production in antiproton-nucleus collisions

    Science.gov (United States)

    Shyam, R.; Tsushima, K.

    2016-10-01

    We study the D ¯D (D¯0D0 and D-D+) charm meson pair production in antiproton (p ¯) induced reactions on nuclei at beam energies ranging from threshold to several GeV. Our model is based on an effective Lagrangian approach that has only the baryon-meson degrees of freedom and involves the physical hadron masses. The reaction proceeds via the t -channel exchanges of Λc+, Σc+, and Σc++ baryons in the initial collision of the antiproton with one of the protons of the target nucleus. The medium effects on the exchanged baryons are included by incorporating in the corresponding propagators, the effective charm baryon masses calculated within a quark-meson coupling (QMC) model. The wave functions of the bound proton have been determined within the QMC model as well as in a phenomenological model where they are obtained by solving the Dirac equation with appropriate scalar and vector potentials. The initial- and final-state distortion effects have been approximated by using an eikonal approximation-based procedure. Detailed numerical results are presented for total and double differential cross sections for the D¯0D0 and D-D+ production reactions on 16O and 90Zr targets. It is noted that at p ¯ beam momenta of interest to the P ¯ ANDA experiment, medium effects lead to noticeable enhancements in the charm meson production cross sections.

  16. Electron beam focusing system

    Energy Technology Data Exchange (ETDEWEB)

    Dikansky, N.; Nagaitsev, S.; Parkhomchuk, V.

    1997-09-01

    The high energy electron cooling requires a very cold electron beam. Thus, the electron beam focusing system is very important for the performance of electron cooling. A system with and without longitudinal magnetic field is presented for discussion. Interaction of electron beam with the vacuum chamber as well as with the background ions and stored antiprotons can cause the coherent electron beam instabilities. Focusing system requirements needed to suppress these instabilities are presented.

  17. Towards an antiproton measurement with AMS-02

    Energy Technology Data Exchange (ETDEWEB)

    Bachlechner, Andreas [RWTH Aachen University (Germany)

    2015-07-01

    AMS-02 is a multi-purpose high-precision particle detector. It has been onboard the International Space Station since May 2011. The antiprotons measurement is an important part of the AMS-02 physics program. An excess above the expected spectrum due to interactions of cosmic rays with the interstellar matter can hint at exotic sources like dark matter annihilation. The antiproton-to-proton ratio and the antiproton flux itself may also improve the understanding of the origin and propagation of cosmic rays. Due to the very small fraction of antiprotons in the cosmic radiation of about 10{sup -5} compared to protons a very precise particle identification is needed. The main backgrounds are other singly charged particles like protons, electrons, and pions produced within the detector material itself. At lower energies the ring-imaging Cherenkov detector and the time-of-flight system help to separate light particles from protons. The electromagnetic calorimeter and the transition radiation detector redundantly suppress the electron background. The reconstruction of the charge sign by the magnetic spectrometer is limited by its resolution and has to be taken into account carefully. The strategies to identify antiprotons in the cosmic-ray measurement in different energy regions are presented. Methods to suppress and the effect of the backgrounds to the antiproton-to-proton ratio are discussed.

  18. Baryon stopping probes deconfinement

    Science.gov (United States)

    Wolschin, Georg

    2016-08-01

    Stopping and baryon transport in central relativistic Pb + Pb and Au + Au collisions are reconsidered with the aim to find indications for the transition from hadronic to partonic processes. At energies reached at the CERN Super Proton Synchrotron ( √{s_{NN}} = 6.3-17.3 GeV) and at RHIC (62.4 GeV) the fragmentation-peak positions as obtained from the data depend linearly on the beam rapidity and are in agreement with earlier results from a QCD-based approach that accounts for gluon saturation. No discontinuities in the net-proton fragmentation peak positions occur in the expected transition region from partons to hadrons at 6-10GeV. In contrast, the mean rapidity loss is predicted to depend linearly on the beam rapidity only at high energies beyond the RHIC scale. The combination of both results offers a clue for the transition from hard partonic to soft hadronic processes in baryon stopping. NICA results could corroborate these findings.

  19. Antiproton Radiotherapy Peripheral Dose from Secondary Neutrons produced in the Annihilation of Antiprotons in the Target

    CERN Document Server

    Fahimian, Benjamin P; Keyes, Roy; Bassler, Niels; Iwamoto, Keisuke S; Zankl, Maria; Holzscheiter, Michael H

    2009-01-01

    The AD-4/ACE collaboration studies the biological effects of antiprotons with respect to a possible use of antiprotons in cancer therapy. In vitro experiments performed by the collaboration have shown an enhanced biological effectiveness for antiprotons relative to protons. One concern is the normal tissue dose resulting from secondary neutrons produced in the annihilation of antiprotons on the nucleons of the target atoms. Here we present the first organ specific Monte Carlo calculations of normal tissue equivalent neutron dose in antiproton therapy through the use of a segmented CT-based human phantom. The MCNPX Monte Carlo code was employed to quantify the peripheral dose for a cylindrical spread out Bragg peak representing a treatment volume of 1 cm diameter and 1 cm length in the frontal lobe of a segmented whole-body phantom of a 38 year old male. The secondary neutron organ dose was tallied as a function of energy and organ.

  20. Antiprotons four times more effective than protons for cell irradiation

    CERN Multimedia

    2006-01-01

    "A pioneering experiment at CERN with potential future application in cancer therapy has produced its first results. Started in 2003, ACE (Antiproton Cell Experiment) is the first investigation of the biological effects of antiprotons." (1,5 page)

  1. Antiprotons four times more effective than protons for cell irradiation

    CERN Multimedia

    2007-01-01

    "A pioneering experiment at CERN with potential future application in cancer therapy has produced its first results. Started in 2003, ACE (Antiproton Cell Experiment) is the first investigation of the biological effects of antiprotons." (1,5 page)

  2. Stop smoking support programs

    Science.gov (United States)

    Smokeless tobacco - stop smoking programs; Stop smoking techniques; Smoking cessation programs; Smoking cessation techniques ... It is hard to quit smoking if you are acting alone. Smokers may have a ... of quitting with a support program. Stop smoking programs ...

  3. Constraining the Higgs portal with antiprotons

    CERN Document Server

    Urbano, Alfredo

    2014-01-01

    The scalar Higgs portal is a compelling model of dark matter (DM) in which a renormalizable coupling with the Higgs boson provides the connection between the visible world and the dark sector. In this paper we investigate the constraint placed on the parameter space of this model by the antiproton data. Due to the fact that the antiproton-to-proton ratio has relative less systematic uncertainties than the antiproton absolute flux, we propose and explore the possibility to combine all the available $\\bar{p}/p$ data. Following this approach, we are able to obtain stronger limits if compared with the existing literature. In particular, we show that most of the parameter space close to the Higgs resonance is ruled out by our analysis. Furthermore, by studying the reach of the future AMS-02 antiproton and antideuteron data, we argue that a DM mass of $\\mathcal{O}(150)$ GeV offers a promising discovery potential. The method of combining all the antiproton-to-proton ratio data proposed in this paper is quite general...

  4. Light meson emission in (anti)proton induced reactions

    CERN Document Server

    Kuraev, E A; Tomasi-Gustafsson, E

    2015-01-01

    Reactions induced by high energy antiprotons on proton on nuclei are accompanied with large probability by the emission of a few mesons. Interesting phenomena can be observed and QCD tests can be performed, through the detection of one or more mesons. The collinear emission from high energy (anti)proton beams of a hard pion or vector meson, can be calculated similarly to the emission of a hard photon from an electron \\cite{Kuraev:2013izz}. This is a well known process in QED, and it is called the "Quasi-Real Electron method", where the incident particle is an electron and a hard photon is emitted leaving an 'almost on shell' electron impinging on the target \\cite{Baier:1973ms}. Such process is well known as Initial State Emission (ISR) method of scanning over incident energy, and can be used, in the hadron case, to produce different kind of particles in similar kinematical conditions. In case of emission of a charged light meson, $\\pi$ or $\\rho$-meson, in proton-proton(anti-proton) collisions, the meson can b...

  5. Study of doubly strange systems using stored antiprotons

    Science.gov (United States)

    Singh, B.; Erni, W.; Krusche, B.; Steinacher, M.; Walford, N.; Liu, B.; Liu, H.; Liu, Z.; Shen, X.; Wang, C.; Zhao, J.; Albrecht, M.; Erlen, T.; Fink, M.; Heinsius, F.; Held, T.; Holtmann, T.; Jasper, S.; Keshk, I.; Koch, H.; Kopf, B.; Kuhlmann, M.; Kümmel, M.; Leiber, S.; Mikirtychyants, M.; Musiol, P.; Mustafa, A.; Pelizäus, M.; Pychy, J.; Richter, M.; Schnier, C.; Schröder, T.; Sowa, C.; Steinke, M.; Triffterer, T.; Wiedner, U.; Ball, M.; Beck, R.; Hammann, C.; Ketzer, B.; Kube, M.; Mahlberg, P.; Rossbach, M.; Schmidt, C.; Schmitz, R.; Thoma, U.; Urban, M.; Walther, D.; Wendel, C.; Wilson, A.; Bianconi, A.; Bragadireanu, M.; Caprini, M.; Pantea, D.; Patel, B.; Czyzycki, W.; Domagala, M.; Filo, G.; Jaworowski, J.; Krawczyk, M.; Lisowski, E.; Lisowski, F.; Michałek, M.; Poznański, P.; Płażek, J.; Korcyl, K.; Kozela, A.; Kulessa, P.; Lebiedowicz, P.; Pysz, K.; Schäfer, W.; Szczurek, A.; Fiutowski, T.; Idzik, M.; Mindur, B.; Przyborowski, D.; Swientek, K.; Biernat, J.; Kamys, B.; Kistryn, S.; Korcyl, G.; Krzemien, W.; Magiera, A.; Moskal, P.; Psyzniak, A.; Rudy, Z.; Salabura, P.; Smyrski, J.; Strzempek, P.; Wronska, A.; Augustin, I.; Böhm, R.; Lehmann, I.; Nicmorus Marinescu, D.; Schmitt, L.; Varentsov, V.; Al-Turany, M.; Belias, A.; Deppe, H.; Dzhygadlo, R.; Ehret, A.; Flemming, H.; Gerhardt, A.; Götzen, K.; Gromliuk, A.; Gruber, L.; Karabowicz, R.; Kliemt, R.; Krebs, M.; Kurilla, U.; Lehmann, D.; Löchner, S.; Lühning, J.; Lynen, U.; Orth, H.; Patsyuk, M.; Peters, K.; Saito, T.; Schepers, G.; Schmidt, C. J.; Schwarz, C.; Schwiening, J.; Täschner, A.; Traxler, M.; Ugur, C.; Voss, B.; Wieczorek, P.; Wilms, A.; Zühlsdorf, M.; Abazov, V. M.; Alexeev, G.; Arefiev, A.; Astakhov, V. I.; Barabanov, M. Yu.; Batyunya, B. V.; Davydov, Yu. I.; Dodokhov, V. Kh.; Efremov, A. A.; Fechtchenko, A.; Fedunov, A. G.; Galoyan, A.; Grigoryan, S.; Koshurnikov, E. K.; Lobanov, V. I.; Lobanov, Y. Yu.; Makarov, A. F.; Malinina, L. V.; Malyshev, V. L.; Olshevskiy, A.; Perevalova, E.; Piskun, A. A.; Pocheptsov, T.; Pontecorvo, G.; Rodionov, V.; Rogov, Y.; Salmin, R.; Samartsev, A.; Sapozhnikov, M. G.; Shabratova, G.; Skachkov, N. B.; Skachkova, A. N.; Strokovsky, E. A.; Suleimanov, M.; Teshev, R.; Tokmenin, V.; Uzhinsky, V.; Vodopyanov, A.; Zaporozhets, S. A.; Zhuravlev, N. I.; Zorin, A. G.; Branford, D.; Glazier, D.; Watts, D.; Böhm, M.; Britting, A.; Eyrich, W.; Lehmann, A.; Pfaffinger, M.; Uhlig, F.; Dobbs, S.; Seth, K.; Tomaradze, A.; Xiao, T.; Bettoni, D.; Carassiti, V.; Cotta Ramusino, A.; Dalpiaz, P.; Drago, A.; Fioravanti, E.; Garzia, I.; Savriè, M.; Akishina, V.; Kisel, I.; Kozlov, G.; Pugach, M.; Zyzak, M.; Gianotti, P.; Guaraldo, C.; Lucherini, V.; Bersani, A.; Bracco, G.; Macri, M.; Parodi, R. F.; Biguenko, K.; Brinkmann, K.; Di Pietro, V.; Diehl, S.; Dormenev, V.; Drexler, P.; Düren, M.; Etzelmüller, E.; Galuska, M.; Gutz, E.; Hahn, C.; Hayrapetyan, A.; Kesselkaul, M.; Kühn, W.; Kuske, T.; Lange, J. S.; Liang, Y.; Metag, V.; Nanova, M.; Nazarenko, S.; Novotny, R.; Quagli, T.; Reiter, S.; Rieke, J.; Rosenbaum, C.; Schmidt, M.; Schnell, R.; Stenzel, H.; Thöring, U.; Ullrich, M.; Wagner, M. N.; Wasem, T.; Wohlfarth, B.; Zaunick, H.; Ireland, D.; Rosner, G.; Seitz, B.; Deepak, P. N.; Kulkarni, A.; Apostolou, A.; Babai, M.; Kavatsyuk, M.; Lemmens, P.; Lindemulder, M.; Loehner, H.; Messchendorp, J.; Schakel, P.; Smit, H.; Tiemens, M.; van der Weele, J. C.; Veenstra, R.; Vejdani, S.; Dutta, K.; Kalita, K.; Kumar, A.; Roy, A.; Sohlbach, H.; Bai, M.; Bianchi, L.; Büscher, M.; Cao, L.; Cebulla, A.; Dosdall, R.; Gillitzer, A.; Goldenbaum, F.; Grunwald, D.; Herten, A.; Hu, Q.; Kemmerling, G.; Kleines, H.; Lehrach, A.; Nellen, R.; Ohm, H.; Orfanitski, S.; Prasuhn, D.; Prencipe, E.; Pütz, J.; Ritman, J.; Schadmand, S.; Sefzick, T.; Serdyuk, V.; Sterzenbach, G.; Stockmanns, T.; Wintz, P.; Wüstner, P.; Xu, H.; Zambanini, A.; Li, S.; Li, Z.; Sun, Z.; Xu, H.; Rigato, V.; Isaksson, L.; Achenbach, P.; Corell, O.; Denig, A.; Distler, M.; Hoek, M.; Karavdina, A.; Lauth, W.; Liu, Z.; Merkel, H.; Müller, U.; Pochodzalla, J.; Schlimme, S.; Sfienti, C.; Thiel, M.; Ahmadi, H.; Ahmed, S.; Bleser, S.; Capozza, L.; Cardinali, M.; Dbeyssi, A.; Deiseroth, M.; Feldbauer, F.; Fritsch, M.; Fröhlich, B.; Jasinski, P.; Kang, D.; Khaneft, D.; Klasen, R.; Leithoff, H. H.; Lin, D.; Maas, F.; Maldaner, S.; Martìnez Rojo, M.; Marta, M.; Michel, M.; Mora Espì, M. C.; Morales Morales, C.; Motzko, C.; Nerling, F.; Noll, O.; Pflüger, S.; Pitka, A.; Rodríguez Piñeiro, D.; Sanchez Lorente, A.; Steinen, M.; Valente, R.; Weber, T.; Zambrana, M.; Zimmermann, I.; Fedorov, A.; Korjik, M.; Missevitch, O.; Boukharov, A.; Malyshev, O.; Marishev, I.; Balanutsa, P.; Balanutsa, V.; Chernetsky, V.; Demekhin, A.; Dolgolenko, A.; Fedorets, P.; Gerasimov, A.

    2016-10-01

    Bound nuclear systems with two units of strangeness are still poorly known despite their importance for many strong interaction phenomena. Stored antiprotons beams in the GeV range represent an unparalleled factory for various hyperon-antihyperon pairs. Their outstanding large production probability in antiproton collisions will open the floodgates for a series of new studies of systems which contain two or even more units of strangeness at the P ‾ ANDA experiment at FAIR. For the first time, high resolution γ-spectroscopy of doubly strange ΛΛ-hypernuclei will be performed, thus complementing measurements of ground state decays of ΛΛ-hypernuclei at J-PARC or possible decays of particle unstable hypernuclei in heavy ion reactions. High resolution spectroscopy of multistrange Ξ--atoms will be feasible and even the production of Ω--atoms will be within reach. The latter might open the door to the | S | = 3 world in strangeness nuclear physics, by the study of the hadronic Ω--nucleus interaction. For the first time it will be possible to study the behavior of Ξ‾+ in nuclear systems under well controlled conditions.

  6. The ELENA Beam Diagnostics Systems

    CERN Document Server

    Tranquille, G

    2013-01-01

    The Extra Low ENergy Antiproton ring (ELENA) to be built at CERN is aimed at substantially increasing the number of antiprotons to the low energy antiproton physics community. It will be a small machine which will decelerate low intensity beams (<4x107) from 5.3 MeV to 100 keV and will be equipped with an electron cooler to avoid beam losses during the deceleration and to significantly reduce beam phase space at extraction. To measure the beam parameters from the extraction point of the Antiproton Decelerator (AD), through the ELENA ring and all the way to the experiments, many systems will be needed to ensure that the desired beam characteristics are obtained. Particular attention needs to be paid to the performance of the electron cooler which depends on reliable instrumentation in order to efficiently cool the antiprotons. This contribution will present the different monitors that have been proposed to measure the various beam parameters as well as some of the developments going on to further improve th...

  7. Antiproton annihilation physics in the Monte Carlo particle transport code SHIELD-HIT12A

    Energy Technology Data Exchange (ETDEWEB)

    Taasti, Vicki Trier; Knudsen, Helge [Dept. of Physics and Astronomy, Aarhus University (Denmark); Holzscheiter, Michael H. [Dept. of Physics and Astronomy, Aarhus University (Denmark); Dept. of Physics and Astronomy, University of New Mexico (United States); Sobolevsky, Nikolai [Institute for Nuclear Research of the Russian Academy of Sciences (INR), Moscow (Russian Federation); Moscow Institute of Physics and Technology (MIPT), Dolgoprudny (Russian Federation); Thomsen, Bjarne [Dept. of Physics and Astronomy, Aarhus University (Denmark); Bassler, Niels, E-mail: bassler@phys.au.dk [Dept. of Physics and Astronomy, Aarhus University (Denmark)

    2015-03-15

    The Monte Carlo particle transport code SHIELD-HIT12A is designed to simulate therapeutic beams for cancer radiotherapy with fast ions. SHIELD-HIT12A allows creation of antiproton beam kernels for the treatment planning system TRiP98, but first it must be benchmarked against experimental data. An experimental depth dose curve obtained by the AD-4/ACE collaboration was compared with an earlier version of SHIELD-HIT, but since then inelastic annihilation cross sections for antiprotons have been updated and a more detailed geometric model of the AD-4/ACE experiment was applied. Furthermore, the Fermi–Teller Z-law, which is implemented by default in SHIELD-HIT12A has been shown not to be a good approximation for the capture probability of negative projectiles by nuclei. We investigate other theories which have been developed, and give a better agreement with experimental findings. The consequence of these updates is tested by comparing simulated data with the antiproton depth dose curve in water. It is found that the implementation of these new capture probabilities results in an overestimation of the depth dose curve in the Bragg peak. This can be mitigated by scaling the antiproton collision cross sections, which restores the agreement, but some small deviations still remain. Best agreement is achieved by using the most recent antiproton collision cross sections and the Fermi–Teller Z-law, even if experimental data conclude that the Z-law is inadequately describing annihilation on compounds. We conclude that more experimental cross section data are needed in the lower energy range in order to resolve this contradiction, ideally combined with more rigorous models for annihilation on compounds.

  8. The antiproton interaction with an internal 12C target inside the HESR ring at FAIR

    Science.gov (United States)

    Introzzi, R.; Balestra, F.; Lavagno, A.; Scozzi, F.; Younis, H.

    2016-04-01

    In order to fulfill the goal of producing higher rates of doubly strange hyperons, the P¯ANDA collaboration will use the antiproton ring HESR at the future facility FAIR. The low energy hyperon production by an antiproton beam requires to insert a solid target inside the ring. Unwanted side effects of such an insertion are the overwhelming amount of annihilations, which would make the detectors blind, and the fast depletion of the bunch, which circulates inside the ring. The choice of the target material impacts the hyperon production yield: Carbon turned out to provide enough initial hyperon deceleration and keep secondary interactions below a tolerable level. The use of a very thin Diamond target, together with beam steering techniques, seems to be a satisfactory solution to the above problems and will be described hereafter.

  9. A Cryogenic Current Comparator for the Low Energy Antiproton Facilities at CERN

    CERN Document Server

    Fernandes, M; Welsch, CP

    2014-01-01

    Several laboratories have shown the potential of using Superconducting QUantum Interference Device (SQUID) magnetometers together with superconductor magnetic shields to measure beam current intensities in the submicro-Ampere regime. CERN, in collaboration with GSI, Jena university and Helmholtz Institute Jena, is currently working on developing an improved version of such a current monitor for the Antiproton Decelerator (AD) and Extra Low ENergy Antiproton (ELENA) rings at CERN, aiming for better current resolution and overall system availability. This contribution will present the current design, including theoretical estimation of the current resolution; stability limits of SQUID systems and adaptation of the coupling circuit to the AD beam parameters; the analysis of thermal and mechanical cryostat modes.

  10. Deceleration of MeV antiprotons and muons to keV energies — the anticyclotron A progress report

    Science.gov (United States)

    Horváth, D.; Aschenauer, E. C.; Cauz, D.; Chatellard, D.; DeCecco, P.; Eades, J.; Egger, J.-P.; Elsener, K.; Eugster, P.; Formisano, F.; Gorini, G.; Hauser, P.; Kottmann, F.; Krafcsik, I.; Lagomarsino, V.; Manuzio, G.; Missimer, J.; Poggiani, R.; Simons, L. M.; Testera, G.; Torelli, G.; Waldner, F.

    1994-03-01

    A progress report is presented on the development of the anticyclotron — deceleration of antiprotons and negative muons via collisions in a low-pressure gas or thin foils during revolutions in a cyclotron field. Beam tests performed at CERN and PSI are reported and future plans for applications outlined.

  11. Deceleration of MeV antiprotons and muons to keV energies - the anticyclotron. A progress report

    Energy Technology Data Exchange (ETDEWEB)

    Horvath, D.; Aschenauer, E.C.; Cauz, D.; Chatellard, D.; DeCecco, P.; Eades, J.; Egger, J.P.; Elsener, K.; Eugster, P.; Formisano, F.; Gorini, G.; Hauser, P.; Kottmann, F.; Krafcsik, I.; Lagomarsino, V.; Manuzio, G.; Missimer, J.; Poggiani, R.; Simons, L.M.; Testera, G.; Torelli, G.; Waldner, F. (KFKI Research Inst. for Particle and Nuclear Physics, Budapest (Hungary) Pisa Univ. (Italy) INFN, Pisa (Italy) Paul Scherrer Inst., Villigen (Switzerland) Univ. di Udine (Italy) Neuchatel Univ. (Switzerland) CERN, Geneva (Switzerland) ETH Zuerich, Villigen (Switzerland) KFKI Research Inst. for Materials Science, Budapest (Hungary) Genova Univ. (Italy) INFN, Genova (Italy))

    1994-03-01

    A progress report is presented on the development of the anticyclotron - deceleration of antiprotons and negative muons via collisions in a low-pressure gas or thin foils during revolutions in a cyclotron field. Beam tests performed at CERN and PSI are reported and future plans for applications outlined. (orig.)

  12. Non-dissociative and dissociative ionisation of H sub 2 by 50-2000 keV antiprotons

    Energy Technology Data Exchange (ETDEWEB)

    Andersen, L.H.; Hvelplund, P.; Knudsen, H.; Moeller, S.P.; Pedersen, J.O.P.; Tang-Petersen, S.; Uggerhoej, E. (Aarhus Univ. (Denmark). Inst. of Physics); Elsener, K. (European Organization for Nuclear Research, Geneva (Switzerland)); Morenzoni, E. (Paul Scherrer Inst. (PSI), Villigen (Switzerland))

    1990-08-14

    A beam of antiprotons with energies between 50 keV and 2 MeV has been used for measurements of non-dissociative ionisation and dissociative ionisation cross sections of H{sub 2}. The results are compared with cross sections for equivelocity protons and electrons, and the role of interference effects in two-electron processes is discussed. (author).

  13. Evaporative Cooling of Antiprotons to Cryogenic Temperatures

    CERN Document Server

    Andresen, G B; Baquero-Ruiz, M; Bertsche, W; Bowe, P D; Butler, E; Cesar, C L; Chapman, S; Charlton, M; Fajans, J; Friesen, T; Fujiwara, M C; Gill, D R; Hangst, J S; Hardy, W N; Hayano, R S; Hayden, M E; Humphries, A; Hydomako, R; Jonsell, S; Kurchaninov, L; Lambo, R; Madsen, N; Menary, S; Nolan, P; Olchanski, K; Olin, A; Povilus, A; Pusa, P; Robicheaux, F; Sarid, E; Silveira, D M; So, C; Storey, J W; Thompson, R I; van der Werf, D P; Wilding, D; Wurtele, J S; Yamazaki, Y

    2010-01-01

    We report the application of evaporative cooling to clouds of trapped antiprotons, resulting in plasmas with measured temperature as low as 9~K. We have modeled the evaporation process for charged particles using appropriate rate equations. Good agreement between experiment and theory is observed, permitting prediction of cooling efficiency in future experiments. The technique opens up new possibilities for cooling of trapped ions and is of particular interest in antiproton physics, where a precise CPT test on trapped antihydrogen is a long-standing goal.

  14. Antiproton radiotherapy: peripheral dose from secondary neutrons

    DEFF Research Database (Denmark)

    Fahimian, Benjamin P.; DeMarco, John J.; Keyes, Roy

    2009-01-01

    is the normal tissue dose resulting from secondary neutrons produced in the annihilation of antiprotons on the nucleons of the target atoms. Here we present the first organ specific Monte Carlo calculations of normal tissue equivalent neutron dose in antiproton therapy through the use of a segmented CT......-based human phantom. The MCNPX Monte Carlo code was employed to quantify the peripheral dose for a cylindrical spread out Bragg peak representing a treatment volume of 1 cm diameter and 1 cm length in the frontal lobe of a segmented whole-body phantom of a 38 year old male. The secondary neutron organ dose...

  15. K-shell ionization by antiprotons

    Energy Technology Data Exchange (ETDEWEB)

    Mehler, G.; Mueller, B.; Greiner, W.; Soff, G.

    1987-08-01

    We present calculations for the impact-parameter dependence of K-shell ionization rates in p-bar-Cu and in p-bar-Ag collisions at various projectile energies. We show that the effect of the attractive Coulomb potential on the Rutherford trajectory and the antibinding effect caused by the negative charge of the antiproton result in a considerable increase of the ionization probability. Total ionization cross sections for proton and antiproton projectiles are compared with each other and with experimental ionization cross sections for protons.

  16. Sensitive beam current measurement for FAIR

    Energy Technology Data Exchange (ETDEWEB)

    Schwickert, Marcus; Kurian, Febin; Reeg, Hansjoerg [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, Darmstadt (Germany); Seidel, Paul; Neubert, Ralf [Friedrich-Schiller-Universitaet Jena (Germany); Geithner, Rene; Vodel, Wolfgang [Helmholtz-Institut Jena (Germany)

    2012-07-01

    Presently FAIR, the Facility for Antiproton and Ion Research, entered the final planning phase at GSI. The new accelerator facility requires precise devices for beam current measurements due to the large dynamics in beam intensities for the various synchrotrons, transport lines and storage rings. We report on the actual developments of beam diagnostic devices for the measurement of beam intensities ranging from 5 x 10{sup 11} uranium ions down to the detection of less than 10{sup 4} antiprotons. This contribution gives an overview of the planned instruments with a focus on non-intercepting beam current transformers, and summarizes the on-going development of a cryogenic current comparator.

  17. The biological effectiveness of antiproton irradiation

    DEFF Research Database (Denmark)

    Holzscheiter, Michael H.; Bassler, Niels; Agazaryan, Nzhde;

    2006-01-01

    Background and purpose: Antiprotons travel through tissue in a manner similar to that for protons until they reach the end of their range where they annihilate and deposit additional energy. This makes them potentially interesting for radiotherapy. The aim of this study was to conduct the first e...

  18. Collisions of antiprotons with hydrogen molecular ions

    DEFF Research Database (Denmark)

    Lühr, Armin Christian; Saenz, Alejandro

    2009-01-01

    Time-dependent close-coupling calculations of the ionization and excitation cross section for antiproton collisions with molecular hydrogen ions are performed in an impact energy range from 0.5 keV to 10 MeV. The Born-Oppenheimer and Franck-Condon approximations as well as the impact parameter...

  19. Technical design report for the PANDA (AntiProton Annihilations at Darmstadt) Straw Tube Tracker. Strong interaction studies with antiprotons

    Energy Technology Data Exchange (ETDEWEB)

    Erni, W.; Keshelashvili, I.; Krusche, B.; Steinacher, M. [Universitaet Basel, Basel (Switzerland); Heng, Y.; Liu, Z.; Liu, H.; Shen, X.; Wang, Q.; Xu, H. [Chinese Academy of Sciences, Institute of High Energy Physics, Beijing (China); Aab, A.; Albrecht, M.; Becker, J.; Csapo, A.; Feldbauer, F.; Fink, M.; Friedel, P.; Heinsius, F.H.; Held, T.; Klask, L.; Koch, H.; Kopf, B.; Leiber, S.; Leyhe, M.; Motzko, C.; Pelizaeus, M.; Pychy, J.; Roth, B.; Schroeder, T.; Schulze, J.; Sowa, C.; Steinke, M.; Trifterer, T.; Wiedner, U.; Zhong, J. [Universitaet Bochum I. Institut fuer Experimentalphysik, Bochum (Germany); Beck, R.; Bianco, S.; Brinkmann, K.T.; Hammann, C.; Hinterberger, F.; Kaiser, D.; Kliemt, R.; Kube, M.; Pitka, A.; Quagli, T.; Schmidt, C.; Schmitz, R.; Schnell, R.; Thoma, U.; Vlasov, P.; Walther, D.; Wendel, C.; Wuerschig, T.; Zaunick, H.G. [Rheinische Friedrich-Wilhelms-Universitaet Bonn, Bonn (Germany); Bianconi, A. [Universita di Brescia, Brescia (Italy); Bragadireanu, M.; Caprini, M.; Pantea, D.; Pantelica, D.; Pietreanu, D.; Serbina, L.; Tarta, P.D. [Institutul National de C and D pentru Fizica si Inginerie Nucleara ' ' Horia Hulubei' ' , Bukarest-Magurele (Romania); Kaplan, D. [IIT, Illinois Institute of Technology, Chicago (United States); Fiutowski, T.; Idzik, M.; Mindur, B.; Przyborowski, D.; Swientek, K. [AGH, University of Science and Technology, Cracow (Poland)] [and others

    2013-02-15

    This document describes the technical layout and the expected performance of the Straw Tube Tracker (STT), the main tracking detector of the PANDA target spectrometer. The STT encloses a Micro-Vertex-Detector (MVD) for the inner tracking and is followed in beam direction by a set of GEM stations. The tasks of the STT are the measurement of the particle momentum from the reconstructed trajectory and the measurement of the specific energy loss for a particle identification. Dedicated simulations with full analysis studies of certain proton-antiproton reactions, identified as being benchmark tests for the whole PANDA scientific program, have been performed to test the STT layout and performance. The results are presented, and the time lines to construct the STT are described. (orig.)

  20. Closing the stop gap

    Energy Technology Data Exchange (ETDEWEB)

    Czakon, Michal [RWTH Aachen Univ. (Germany). Inst. fuer Theoretische Teilchnphysik und Kosmologie; Mitov, Alexander [Univ. of Cambridge (United Kingdom). Cavendish Lab.; Papucci, Michele [Lawrence Berkeley National Laboratory, CA (United States). Theoretical Physics Group; California Univ., Berkeley, CA (United States). Dept. of Physics; Ruderman, Joshua T. [Lawrence Berkeley National Laboratory, CA (United States). Theoretical Physics Group; California Univ., Berkeley, CA (United States). Dept. of Physics; New York Univ., NY (United States). Center for Cosmology and Particle Physics; Weiler, Andreas [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); CERN - European Organization for Nuclear Research, Geneva (Switzerland). Theory Div.

    2014-07-15

    Light stops are a hallmark of the most natural realizations of weak-scale supersymmetry. While stops have been extensively searched for, there remain open gaps around and below the top mass, due to similarities of stop and top signals with current statistics. We propose a new fast-track avenue to improve light stop searches for R-parity conserving supersymmetry, by comparing top cross section measurements to the theoretical prediction. Stop masses below ∝180 GeV can now be ruled out for a light neutralino. The possibility of a stop signal contaminating the top mass measurement is also briefly addressed.

  1. The proton injector for the accelerator facility of antiproton and ion research (FAIR)

    Energy Technology Data Exchange (ETDEWEB)

    Ullmann, C., E-mail: c.ullmann@gsi.de; Kester, O. [GSI Helmholtzzentrum für Schwerionenforschung GmbH, Planckstr. 1, 64291 Darmstadt (Germany); Institut für Angewandte Physik, Goethe-Universität Frankfurt, Max-von-Laue-Str. 1, 60438 Frankfurt/Main (Germany); Berezov, R.; Fils, J.; Hollinger, R.; Vinzenz, W. [GSI Helmholtzzentrum für Schwerionenforschung GmbH, Planckstr. 1, 64291 Darmstadt (Germany); Chauvin, N.; Delferriere, O. [Commissariat à l’Energie Atomique et aux Energies Alternatives, IRFU, F-91191-Gif-sur-Yvette (France)

    2014-02-15

    The new international accelerator facility for antiproton and ion research (FAIR) at GSI in Darmstadt, Germany, is one of the largest research projects worldwide and will provide an antiproton production rate of 7 × 10{sup 10} cooled pbars per hour. This is equivalent to a primary proton beam current of 2 × 10{sup 16} protons per hour. For this request a high intensity proton linac (p-linac) will be built with an operating rf-frequency of 325 MHz to accelerate a 35 mA proton beam at 70 MeV, using conducting crossed-bar H-cavities. The repetition rate is 4 Hz with beam pulse length of 36 μs. The microwave ion source and low energy beam transport developed within a joint French-German collaboration GSI/CEA-SACLAY will serve as an injector of the compact proton linac. The 2.45 GHz ion source allows high brightness ion beams at an energy of 95 keV and will deliver a proton beam current of 100 mA at the entrance of the radio frequency quadrupole (RFQ) within an acceptance of 0.3π mm mrad (norm., rms)

  2. Antiproton production in Au + Au collisions at 11.7 A{center_dot}GeV/c

    Energy Technology Data Exchange (ETDEWEB)

    Sako, Hiroyuki [Tokyo Univ. (Japan)

    1997-02-01

    We investigated the dependence of antiproton yields on the number of wounded projectile nucleons (N{sub proj}). The dN/dy/N{sub proj} of antiprotons with the beam energy correction is almost constant from p+A to Si+A collisions, while it decreases in Au+Au collisions to 30-60% of the constant. Next, we have compared dependence of ratios of dN/dy, p-bar/{pi}{sup -}, p/{pi}{sup -}, K{sup -}/{pi}{sup -}, K{sup +}/{pi}{sup -}, and {pi}{sup +}/{pi}{sup -} at 1.2antiprotons in Au+Au collisions is much stronger than in p+A and Si+A collisions. We have compared the antiproton data with the RQMD model. In RQMD, antiprotons are produced initially from multi-step excitation processes and some of them are absorbed by nucleons with free NN-bar annihilation cross sections. RQMD reproduces overall tendencies of antiproton yields from p+A to Au+Au collisions within 50%. Finally, we explored the relation between baryon densities and antiproton yields in A+A collisions. We used a model in a static participant volume with the RQMD initial production and the absorption length with the free NN-bar annihilation cross section. In the model, only the antiprotons produced around the surface of the participant volume can survive. The model reproduces the scaling of experimental antiproton yields with the 2/3 power of the number of participants. By comparing the model with the experimental data, it is found that the ratio of the mean baryon density to the surface baryon density is 3-4 independent of collision systems. (J.P.N.). 109 refs.

  3. Investigation of silicon sensors for their use as antiproton annihilation detectors

    Energy Technology Data Exchange (ETDEWEB)

    Pacifico, N., E-mail: nicola.pacifico@cern.ch [University of Bergen, Institute of Physics and Technology, Allégaten 55, 5007 Bergen (Norway); Aghion, S. [Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano (Italy); Istituto Nazionale di Fisica Nucleare, Sez. di Milano, Via Celoria 16, 20133 Milano (Italy); Ahlén, O. [European Organisation for Nuclear Research, Physics Department, 1211 Geneva 23 (Switzerland); Belov, A.S. [Institute for Nuclear Research of the Russian Academy of Sciences, Moscow 117312 (Russian Federation); Bonomi, G. [University of Brescia, Department of Mechanical and Industrial Engineering, Via Branze 38, 25133 Brescia (Italy); Istituto Nazionale di Fisica Nucleare, Sez. di Pavia, Via Agostino Bassi 6, 27100 Pavia (Italy); Bräunig, P. [Kirchhoff Institute for Physics, Im Neuenheimer Feld 227, 69120 Heidelberg (Germany); Bremer, J. [European Organisation for Nuclear Research, Physics Department, 1211 Geneva 23 (Switzerland); Brusa, R.S. [Department of Physics, University of Trento, via Sommarive 14, 38123 Povo, Trento (Italy); INFN-TIFPA, via Sommarive 14, 38123 Povo, Trento (Italy); Burghart, G. [European Organisation for Nuclear Research, Physics Department, 1211 Geneva 23 (Switzerland); Cabaret, L. [Laboratoire Aimé Cotton, CNRS, Université Paris Sud, ENS Cachan, Bâtiment 505, Campus d' Orsay, 91405 Orsay Cedex (France); Caccia, M. [University of Insubria, Dipartimento di Scienza ed Alta Tecnologia, via Valleggio 11, Como (Italy); Canali, C. [University of Zurich, Physics Institute, Winterthurerstrasse 190, 8057 Zurich (Switzerland); Caravita, R. [Istituto Nazionale di Fisica Nucleare, Sez. di Genova, Via Dodecaneso 33, 16146 Genova (Italy); University of Genoa, Department of Physics, Via Dodecaneso 33, 16146 Genova (Italy); Castelli, F. [University of Milano, Department of Physics, Via Celoria 16, 20133 Milano (Italy); and others

    2014-11-21

    We present here a new application of silicon sensors aimed at the direct detection of antinucleons annihilations taking place inside the sensor's volume. Such detectors are interesting particularly for the measurement of antimatter properties and will be used as part of the gravity measurement module in the AEg{sup ¯}IS experiment at the CERN Antiproton Decelerator. One of the goals of the AEg{sup ¯}IS experiment is to measure the gravitational acceleration of antihydrogen with 1% precision. Three different silicon sensor geometries have been tested with an antiproton beam to investigate their properties as annihilation detection devices: strip planar, 3D pixels and monolithic pixel planar. In all cases we were successfully detecting annihilations taking place in the sensor and we were able to make a first characterization of the clusters and tracks.

  4. Scattered antiproton polarization in pp elastic scattering at 220 MeV in bubble chamber

    CERN Document Server

    Ohsugi, T

    1973-01-01

    The polarization of antiproton scattering in pp elastic collision has been measured in the four intervals of the CM scattering angle theta /sup */ less than 90 degrees by means of double scattering in a bubble chamber. The analysis has been performed on the basis of 999 double elastic events which have been found in about 100K pictures of the 81- cm Saclay hydrogen bubble chamber exposed to a 0.7 GeV/c antiproton beam from the CERN PS. The obtained values of polarization show the maximum value 0.52+or-0.19 at theta /sup */=56 degrees . The polarization for pp scattering seems to be larger than that for pp scattering. The results are also compared with the potential model by Bryan and Phillips (1968) and with the modified diffraction model by Frahn and Venter (1964). Possible systematic errors in the present experiment are discussed in detail. (17 refs).

  5. Report on the first VLHC photon stop cryogenic design experiment

    CERN Document Server

    Geynisman, M; Bossert, R; Darve, C; Ewald, K D; Klebaner, A; Limon, P; Martínez, A

    2004-01-01

    As part of Fermilab's study of a Very Large Hadron Collider (VLHC), a water-cooled photon stop was proposed as a device to intercept the synchrotron radiation emitted by the high-energy proton beams in the high-field superconducting magnets with minimal plug-cooling power. Photon stops are radiation absorbers operating at room temperature that protrude into the beam tube at the end of each bending magnet to scrape the synchrotron light emitted by the beam one magnet up- stream. Among the technological challenges regarding photon stops is their cryo-design. The photon stop is water-cooled and operates in a cryogenic environment. A careful cryo-design is therefore essential to enable operation at minimum heat transfer between the room temperature sections and the cryogenic parts. A photon stop cryo- design was developed and a prototype was built. This paper presents the results of the cryogenic experiments conducted on the first VLHC photon-stop prototype.

  6. Physics at CERN’s Antiproton Decelerator

    Science.gov (United States)

    Hori, M.; Walz, J.

    2013-09-01

    The Antiproton Decelerator (AD) facility of CERN began operation in 1999 to serve experiments for studies of CPT invariance by precision laser and microwave spectroscopy of antihydrogen (Hbar ) and antiprotonic helium (pbar He) atoms. The first 12 years of AD operation saw cold Hbar synthesized by overlapping clouds of positrons (e+) and antiprotons (pbar ) confined in magnetic Penning traps. Cold Hbar was also produced in collisions between Rydberg positronium (Ps) atoms and pbar . Ground-state Hbar was later trapped for up to ˜1000 s in a magnetic bottle trap, and microwave transitions excited between its hyperfine levels. In the pbar He atom, deep ultraviolet transitions were measured to a fractional precision of (2.3-5)×10-9 by sub-Doppler two-photon laser spectroscopy. From this the antiproton-to-electron mass ratio was determined as M/me=1836.1526736(23), which agrees with the p value known to a similar precision. Microwave spectroscopy of pbar He yielded a measurement of the pbar magnetic moment with a precision of 0.3%. More recently, the magnetic moment of a single pbar confined in a Penning trap was measured with a higher precision, as μ=-2.792845(12)μ in nuclear magnetons. Other results reviewed here include the first measurements of the energy loss (-dE/dx) of 1-100 keV pbar traversing conductor and insulator targets; the cross sections of low-energy (therapy. New experiments under preparation attempt to measure the gravitational acceleration of Hbar or synthesize H. Several other future experiments will also be briefly described.

  7. Antiproton-Proton Glory Scattering

    CERN Multimedia

    2002-01-01

    This experiment measures @*p and K|-p backwards scattering between 8 and 16 GeV/c in the Omega spectrometer using the S1 beam, with sensitivities of several events per nanobarn. The mechanism responsible for backward scattering in channels not mediated by particle exchange is not understood, and could be almost energy-independent glory scattering, especially since relatively high cross sections of 190~(@*p) and 120~(K|-p)nb have been measured earlier at 5~GeV/c. @p|-p backwards scattering is measured for monitoring purposes. The trigger requires a forward particle of momentum close to the beam momentum. Absence of light in the two forward Cerenkov counters indicates that the particle is a proton. Combinations of an incident @p|- and an outgoing K|+, or an incident K|- or @* and an outgoing @p|+, cover the following byproducts: @*p~@A~@p|+@p|- which is an (allowed) baryon exchange reaction, and the exotic exchange reactions @p|-p~@A~K|+Y K|-p~@A~@p|+Y|-, where Y|- may be the @S|- or the Y*|-(1385).

  8. Antiproton nucleus potentials from global fits to antiprotonic X-rays and radiochemical data

    Science.gov (United States)

    Friedman, E.; Gal, A.; Mareš, J.

    2005-11-01

    We report on global fits of optical-model parameters to 90 data points for p¯ X-rays and 17 data points of radiochemical data put together. By doing separate fits to the two kinds of data it is possible to determine phenomenologically the radial region where the absorption of antiprotons takes place and to obtain neutron densities which represent the average behaviour over the periodic table. A finite-range attractive and absorptive p¯-nuclear isoscalar potential fits the data well. Self-consistent dynamical calculations within the RMF model demonstrate that the polarization of the nucleus by the atomic antiproton is negligible.

  9. Sub-ppm laser spectroscopy of antiprotonic helium and a CPT-violation limit on the antiprotonic charge and mass.

    Science.gov (United States)

    Hori, M; Eades, J; Hayano, R S; Ishikawa, T; Sakaguchi, J; Widmann, E; Yamaguchi, H; Torii, H A; Juhász, B; Horváth, D; Yamazaki, T

    2001-08-27

    Six laser-resonant transitions have been detected in metastable antiprotonic helium atoms produced at the CERN Antiproton Decelerator. They include UV transitions from the last metastable states in the v = n-l-1 = 0 and 1 cascades. Zero-density frequencies were obtained from measured pressure shifts with fractional precisions between 1.3 x 10(-7) and 1.6 x 10(-6). By comparing these with QED calculations and the antiproton cyclotron frequency, we deduce that the antiproton and proton charges and masses agree to within 6 x 10(-8) with a confidence level of 90%.

  10. Elastic scattering, polarization and absorption of relativistic antiprotons on nuclei

    CERN Document Server

    Larionov, A B

    2016-01-01

    We perform Glauber model calculations of the antiproton-nucleus elastic and quasielastic scattering and absorption in the beam momentum range $\\sim 0.5\\div10$ GeV/c. A good agreement of our calculations with available LEAR data and with earlier Glauber model studies of the $\\bar p A$ elastic scattering allows us to make predictions at the beam momenta of $\\sim 10$ GeV/c, i.e at the regime of the PANDA experiment at FAIR. The comparison with the proton-nucleus elastic scattering cross sections shows that the diffractive minima are much deeper in the $\\bar p A$ case due to smaller absolute value of the ratio of the real-to-imaginary part of the elementary elastic amplitude. Significant polarization signal for $\\bar p A$ elastic scattering at 10 GeV/c is expected. We have also revealed a strong dependence of the $\\bar p A$ absorption cross section on the slope parameter of the transverse momentum dependence of the elementary $\\bar pN$ amplitude. The $\\bar p A$ optical potential is discussed.

  11. Elastic scattering, polarization and absorption of relativistic antiprotons on nuclei

    Science.gov (United States)

    Larionov, A. B.; Lenske, H.

    2017-01-01

    We perform Glauber model calculations of the antiproton-nucleus elastic and quasielastic scattering and absorption in the beam momentum range ∼ 0.5 ÷ 10 GeV / c. A good agreement of our calculations with available LEAR data and with earlier Glauber model studies of the p bar A elastic scattering allows us to make predictions at the beam momenta of ∼10 GeV/c, i.e. at the regime of the PANDA experiment at FAIR. The comparison with the proton-nucleus elastic scattering cross sections shows that the diffractive minima are much deeper in the p bar A case due to smaller absolute value of the ratio of the real-to-imaginary part of the elementary elastic amplitude. Significant polarization signal for p bar A elastic scattering at 10 GeV/c is expected. We have also revealed a strong dependence of the p bar A absorption cross section on the slope parameter of the transverse momentum dependence of the elementary p bar N amplitude. The p bar A optical potential is discussed.

  12. Measurement of strong interaction effects in antiprotonic helium atoms

    Energy Technology Data Exchange (ETDEWEB)

    Davies, J.D.; Gorringe, T.P.; Lowe, J.; Nelson, J.M.; Playfer, S.M.; Pyle, G.J.; Squier, G.T.A. (Birmingham Univ. (UK). Dept. of Physics); Baker, C.A.; Batty, C.J.; Clark, S.A.

    1984-09-27

    The strong interaction shift and width for the 2 p level and the width for the 3d level have been measured for antiprotonic helium atoms. The results are compared with optical model calculations. The possible existence of strongly bound antiproton states in nuclei is discussed.

  13. Progress in Antiproton Production at the Fermilab Tevatron Collider

    Energy Technology Data Exchange (ETDEWEB)

    Pasquinelli, Ralph J.; Drendel, Brian; Gollwitzer, Keith; Johnson, Stan; Lebedev, Valeri; Leveling, Anthony; Morgan, James; Nagaslaev, Vladimir; Peterson, Dave; Sondgeroth, Alan; Werkema, Steve; /Fermilab

    2009-04-01

    Fermilab Collider Run II has been ongoing since 2001. During this time peak luminosities in the Tevatron have increased from approximately 10 x 10{sup 30} cm{sup -2}sec{sup -1} to 300 x 10{sup 30} cm{sup 02}sec{sup -1}. A major contributing factor in this remarkable performance is a greatly improved antiproton production capability. Since the beginning of Run II, the average antiproton accumulation rate has increased from 2 x 10{sup 10}{anti p}/hr to about 24 x 10{sup 10}{anti p}/hr. Peak antiproton stacking rates presently exceed 28 x 10{sup 10}{anti p}/hr. The antiproton stacking rate has nearly doubled since 2005. It is this recent progress that is the focus of this paper. The process of transferring antiprotons to the Recycler Ring for subsequent transfer to the collider has been significantly restructured and streamlined, yielding additional cycle time for antiproton production. Improvements to the target station have greatly increased the antiproton yield from the production target. The performance of the Antiproton Source stochastic cooling systems has been enhanced by upgrades to the cooling electronics, accelerator lattice optimization, and improved operating procedures. In this paper, we will briefly report on each of these modifications.

  14. Antiproton impact ionization of atomic hydrogen and helium

    Energy Technology Data Exchange (ETDEWEB)

    McGovern, M; Walters, H R J [Department of Applied Mathematics and Theoretical Physics, Queen' s University, Belfast BT7 INN (United Kingdom); Assafrao, D; Mohallem, J R [Laboratorio de Atomos e Moleculas Especiais, Departamento de Fisica, ICEx, Universidade Federal de Minas Gerais, P.O Box 702, 30123-970 Belo Horizonte, MG (Brazil); Whelan, Colm T, E-mail: mmcgovern06@qub.ac.u [Department of Physics, Old Dominion University, Norfolk, VA 23529-0116 (United States)

    2009-11-01

    We shall present results for antiproton ionization of H and He ranging from fully differential cross sections to total ionization. The calculations have been made in a coupled pseudostate impact parameter approximation. It will be shown that the interaction between the antiproton and the target nucleus is very important at low energies.

  15. Detailed analysis of observed antiprotons in cosmic rays

    Directory of Open Access Journals (Sweden)

    P Davoudifar

    2009-12-01

    Full Text Available In the present work, the origin of antiprotons observed in cosmic rays (above the atmosphere is analyzed in details. We have considered the origin of the primaries, (which their interactions with the interstellar medium is one of the most important sources of antiprotons is a supernova type II then used a diffusion model for their propagation. We have used the latest parameterization for antiproton production cross section in pp collisions (instead of well known parameterization introduced by Tan et al. as well as our calculated residence time for primaries. The resulted intensity shows the secondary antiprotons produced in pp collisions in the galaxy, have a high population as one can not consider an excess for extragalactic antiprotons. Also there is a high degree of uncertainty in different parameters.

  16. Antiproton cloud compression in the ALPHA apparatus at CERN

    Energy Technology Data Exchange (ETDEWEB)

    Gutierrez, A., E-mail: andrea.gutierrez@triumf.ca [University of British Columbia, Department of Physics and Astronomy (Canada); Ashkezari, M. D. [Simon Fraser University, Department of Physics (Canada); Baquero-Ruiz, M. [University of California at Berkeley, Department of Physics (United States); Bertsche, W. [University of Manchester, School of Physics and Astronomy (United Kingdom); Burrows, C. [Swansea University, Department of Physics, College of Science (United Kingdom); Butler, E. [Centre for Cold Matter, Imperial College (United Kingdom); Capra, A. [York University, Department of Physics and Astronomy (Canada); Cesar, C. L. [Universidade Federal do Rio de Janeiro, Instituto de Física (Brazil); Charlton, M. [Swansea University, Department of Physics, College of Science (United Kingdom); Dunlop, R. [Simon Fraser University, Department of Physics (Canada); Eriksson, S. [Swansea University, Department of Physics, College of Science (United Kingdom); Evetts, N. [University of British Columbia, Department of Physics and Astronomy (Canada); Fajans, J. [University of California at Berkeley, Department of Physics (United States); Friesen, T. [Aarhus University, Department of Physics and Astronomy (Denmark); Fujiwara, M. C.; Gill, D. R. [TRIUMF (Canada); Hangst, J. S. [Aarhus University, Department of Physics and Astronomy (Denmark); Hardy, W. N. [University of British Columbia, Department of Physics and Astronomy (Canada); Hayden, M. E. [Simon Fraser University, Department of Physics (Canada); Isaac, C. A. [Swansea University, Department of Physics, College of Science (United Kingdom); and others

    2015-11-15

    We have observed a new mechanism for compression of a non-neutral plasma, where antiprotons embedded in an electron plasma are compressed by a rotating wall drive at a frequency close to the sum of the axial bounce and rotation frequencies. The radius of the antiproton cloud is reduced by up to a factor of 20 and the smallest radius measured is ∼ 0.2 mm. When the rotating wall drive is applied to either a pure electron or pure antiproton plasma, no compression is observed in the frequency range of interest. The frequency range over which compression is evident is compared to the sum of the antiproton bounce frequency and the system’s rotation frequency. It is suggested that bounce resonant transport is a likely explanation for the compression of antiproton clouds in this regime.

  17. Intensity-Frontier Antiproton Physics with The Antiproton Annihilation Spectrometer (TAPAS) at Fermilab

    Energy Technology Data Exchange (ETDEWEB)

    Apollinari, Giorgio; /Fermilab; Asner, David M.; /PNL, Richland; Baldini, Wander; /INFN, Ferrara; Bartoszek, Larry; Broemmelsiek, Daniel R.; Brown, Charles N.; /Fermilab; Chakravorty, Alak; /St. Xavier U., Chicago; Colas, Paul; /Saclay; Derwent, Paul; /Fermilab; Drutskoy, Alexey; /Moscow, ITEP; Fortner, Michael; /Northern Illinois U. /Saclay /Indian Inst. Tech., Hyderabad

    2011-11-01

    The Fermilab Antiproton Source is the world's most intense source of antimatter. With the Tevatron program now behind us, this unique facility can help make the case for Fermilab's continued accelerator operations. The Antiproton Source can be used for unique, dedicated antimatter studies, including medium-energy {bar p}-annihilation experiments. We propose to assemble a powerful, yet cost-effective, solenoidal magnetic spectrometer for antiproton-annihilation events, and to use it at the Fermilab Antiproton Accumulator to measure the charm production cross section, study rare hyperon decays, search for hyperon CP asymmetry, precisely measure the properties of several charmonium and nearby states, and make the first measurements of the Drell-Yan continuum in medium-energy antiproton annihilation. Should the charm production cross section be as large as some have proposed, we will also be able to measure D{sup 0}-{bar D}{sup 0} mixing with high precision and discover (or sensitively limit) charm CP violation. The observation of charm or hyperon CP violation would be evidence for physics beyond the Standard Model, with possible implications for the origin of the baryon asymmetry of the universe - the question of what happened to all the antimatter that must have been produced in the Big Bang. The experiment will be carried out by an international collaboration and will require some four years of running time. As possibly the sole hadron experiment in progress at Fermilab during that time, it will play an important role in maintaining a broad particle physics program at Fermilab and in the U.S. It will thus help us to continue attracting creative and capable young people into science and technology, and introducing them to the important technologies of accelerators, detectors, and data acquisition and analysis - key roles in society that accelerator-based particle physics has historically played.

  18. The FLUKA study of the secondary particles fluence in the AD-Antiproton Decelerator target area

    CERN Document Server

    Calviani, M

    2014-01-01

    In this paper we present Monte Carlo FLUKA simulations [1, 2] carried out to investigate the secondary particles fluence emerging from the antiproton production target and their spatial distribution in the AD target area. The detailed quantitative analysis has been performed for different positions along the magnet dog-leg as well as after the main collimator. These results allow tuning the position of the new beam current transformers (BCT) in the target area, in order to have a precise pulse-by-pulse evaluation of the intensity of negative particles injected in the AD-ring before the deceleration phase.

  19. A gas cell for stopping, storing and polarizing radioactive particles

    CERN Document Server

    Sytema, A; Böll, O; Chernowitz, D; Dijck, E A; Grasdijk, J O; Hoekstra, S; Jungmann, K; Mathavan, S C; Meinema, C; Mohanty, A; Müller, S E; Portela, M Nuñez; Onderwater, C J G; Pijpker, C; Willmann, L; Wilschut, H W

    2016-01-01

    A radioactive beam of 20Na is stopped in a gas cell filled with Ne gas. The stopped particles are polarized by optical pumping. The degree of polarization that can be achieved is studied. A maximum polarization of 50% was found. The dynamic processes in the cell are described with a phenomenological model.

  20. A gas cell for stopping, storing and polarizing radioactive particles

    NARCIS (Netherlands)

    Sytema, Auke; van den Berg, Joost; Böll, Oliver; Chernowitz, Daniel; Dijck, Elwin; Grasdijk, Jan; Hoekstra, Steven; Jungmann, Klaus-Peter; Chirayath Mathavan, Sreekanth; Meinema, Jacoba Roelien; Mueller, Stefan E.; Portela, M. N.; Onderwater, Cornelis; Pijpker, Coen; Willmann, Lorenz; Wilschut, H. W.

    2016-01-01

    A radioactive beam of Na-20 is stopped in a gas cell filled with Ne gas. The stopped particles are polarized by optical pumping. The degree of polarization that can be achieved is studied. A maximum polarization of 50% was found. The dynamic processes in the cell are described with a phenomenologica

  1. Cooling of ions and antiprotons with magnetized electrons

    CERN Document Server

    Mollers, B; Walter, M; Zwicknagel, G; Carli, Christian; Nersisyan, H

    2004-01-01

    Electron cooling is a well-established method to improve the phase space quality of ion beams in storage rings. More recently antiprotons have been cooled in traps, first by electrons and then by positrons in order to produce antihydrogen atoms as simplest form of antimatter for CPT-tests. During these cooling processes the light particles are guided by strong external magnetic fields which imposes a challenge to the theoretical description. Within the binary collision model we treat the Coulomb interaction as second-order perturbation to the helix motion of the light particles and also by numerical simulations. In the complementary dielectric theory we calculate the polarization of the light particles by solving the nonlinear Vlasov-Poisson equation as well as linear response. It turns out that the linearization becomes dubious at low ion velocities. In the presence of a strong magnetic field the numerically expensive solution of the Vlasov-Poisson equation is the method of choice, alternatively one may empl...

  2. Advanced Space Propulsion Study - Antiproton and Beamed Power Propulsion

    Science.gov (United States)

    1987-10-01

    34. Physikalisches Inst., There will be no prcceedings. Physikzentrum, Sommerfeldstr., "pies of presentations must be D-5100 Aachen, Germany. obtained from the...Propulsion," (in English), Zeitschrift ftr Flugwissenschaften und Weltraimforschung 10, 393- 400 (November/December 1988). [Bdi I do not see how production...the Phase," Preprint BERN 86-1370 (July 1986), Physikalisches Inst., Univ. Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland. L.A. Kondratyuk and M.G

  3. Concept for the Antiproton Production Target at FAIR

    CERN Document Server

    Knie, K; Franzke, B; Gostishchev, V; Steck, M; Sievers, P

    2012-01-01

    This report summarizes the status of the antiproton (pbar) production area at the future FAIR (Facility for Antiproton and Ion Research) complex at GSI, Darmstadt [1]. This area is composed of the pbar production target, a magnetic horn for the collection of the pbars, and the pbar separator between target and Collector Ring (CR). The emphasis is on the optimization of the accumulation rate of antiprotons to maximize the expected peak and average luminosity for the experiment. As the doses in the target area will be very high, also radiation protection issues will be addressed.

  4. High precision spectroscopy of pionic and antiprotonic atoms; Spectroscopie de precision des atomes pioniques et antiprotoniques

    Energy Technology Data Exchange (ETDEWEB)

    El-Khoury, P

    1998-04-15

    The study of exotic atoms, in which an orbiting electron of a normal atom is replaced by a negatively charged particle ({pi}{sup -}, {mu}{sup -}, p, {kappa}{sup -}, {sigma}{sup -},...) may provide information on the orbiting particle and the atomic nucleus, as well as on their interaction. In this work, we were interested in pionic atoms ({pi}{sup -14} N) on the one hand in order to determine the pion mass with high accuracy (4 ppm), and on the other hand in antiprotonic atoms (pp-bar) in order to study the strong nucleon-antinucleon interaction at threshold. In this respect, a high-resolution crystal spectrometer was coupled to a cyclotron trap which provides a high stop density for particles in gas targets at low pressure. Using curved crystals, an extended X-ray source could be imaged onto the detector. Charge-Coupled Devices were used as position sensitive detectors in order to measure the Bragg angle of the transition to a high precision. The use of gas targets resolved the ambiguity owing to the number of K electrons for the value of the pion mass, and, for the first time, strong interaction shift and broadening of the 2p level in antiprotonic hydrogen were measured directly. (author)

  5. (Light) Stop Signs

    CERN Document Server

    Han, Zhenyu; Krohn, David; Reece, Matthew

    2012-01-01

    Stop squarks with a mass just above the top's and which decay to a nearly massless LSP are difficult to probe because of the large SM di-top background. Here we discuss search strategies which could be used to set more stringent bounds in this difficult region. In particular, we note that both the rapidity difference Delta y(t,tbar) and spin correlations (inferred from, for example, Delta phi(l+,l-)) are sensitive to the presence of stops. We emphasize that systematic uncertainties in top quark production can confound analyses looking for stops, making theoretical and experimental progress on the understanding of Standard Model top production at high precision a very important task. We estimate that spin correlation alone, which is relatively robust against such systematic uncertainties, can exclude a 200 GeV stop at 95% confidence with 20 fb^-1 at the 8 TeV LHC.

  6. Vaccines Stop Illness

    Science.gov (United States)

    Skip Navigation Bar Home Current Issue Past Issues Vaccines Stop Illness Past Issues / Spring 2008 Table of ... meningitis won't infect, cripple, or kill children. Vaccine Safety In light of recent questions about vaccine ...

  7. Depression - stopping your medicines

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/patientinstructions/000570.htm Depression - stopping your medicines To use the sharing features ... prescription medicines you may take to help with depression, anxiety, or pain. Like any medicine, there are ...

  8. "Stop Diabetes Now!"

    Science.gov (United States)

    ... of this page please turn Javascript on. Feature: Diabetes "Stop Diabetes Now!" Past Issues / Fall 2009 Table of Contents ... Tips for Seniors at Risk for Type 2 Diabetes Lifestyle changes that lead to weight loss—such ...

  9. Conceptual designs for antiproton space propulsion systems

    Energy Technology Data Exchange (ETDEWEB)

    Cassenti, B.N.

    1989-01-01

    Five conceptual designs for antimatter space propulsion systems were compared in terms of their performance characteristics. The systems examined included solid-core liquid-propellant rockets; magnetically confined gaseous-core rockets using liquid or solid propellants; plasma-core rockets; pion rockets, which are driven directly by the mass annihilation products; and ram-augmented rockets, in which antiproton annihilation is used to heat hydrogen collected in interstellar space. It was found that, in general, as the specific impulse of the propulsion system increases, the thrust decreases. The comparison between designs showed that only fusion rockets have the capability to compete in performance with mass annihilation rockets. For very-high-speed interstellar missions, pion rockets, which can have a specific impulse of 20 million sec (although with a thrust-to-engine mass ratios of only 0.01 G) will offer best performance. 36 refs.

  10. Particle production in antiproton induced nuclear reactions

    CERN Document Server

    Feng, Zhao-Qing

    2014-01-01

    The quantum molecular dynamics model has been improved to investigate the reaction dynamics induced by antiprotons. The reaction channels of elastic scattering, annihilation, charge exchange and inelastic collisions have been included in the model. Dynamics on particle production, in particular pions, kaons, antikaons and hyperons, is investigated in collisions of $\\overline{p}$ on $^{12}$C, $^{20}$Ne, $^{40}$Ca, $^{112}$Sn, $^{181}$Ta, $^{197}$Au and $^{238}$U from a low to high incident momentum. The rapidity and momentum distributions of $\\pi^{+}$ and protons from the LEAR measurements can be well reproduced. The impacts of system size and incident momentum on particle emissions are investigated from the inclusive spectra, transverse momentum and rapidity distributions. It is found that the annihilations of $\\overline{p}$ on nucleons are of importance on the particle production. Hyperons are mainly produced via meson induced reactions on nucleons and strangeness exchange collisions when the incident moment...

  11. Fragmentation of methane molecules by antiproton impact

    Science.gov (United States)

    Salehzadeh, Arash; Kirchner, Tom

    2016-09-01

    Extending previous work for proton impact, we have investigated the fragmentation of methane molecules due to collisions with antiprotons in the 25 keV to 5 MeV impact energy range. The multi-center nature of the problem is addressed by using a spectral representation of the molecular Hartree-Fock-level Hamiltonian and a single-center expansion of the initially populated molecular orbitals. The two-center basis generator method (TC-BGM) is used for orbital propagation. Electron-removal cross sections obtained from the TC-BGM solutions are complemented with a dynamical decay-route fragmentation model to calculate cross sections for the production of fragment ions. Good agreement with the available experimental data is observed for CH4+,CH3+,CH2+and CH+. Work supported by NSERC, Canada.

  12. Antiproton cell experiment: antimatter is a better killer

    CERN Multimedia

    2006-01-01

    "European Organization for Nuclear Research is reporting that results from a three year study of antiprotons for neoplasm irrdiation showed a better cellular killer with a smaller lethal dose." (1,5 page)

  13. Antiprotons from dark matter annihilation in the Galaxy: astrophysical uncertainties

    CERN Document Server

    Evoli, Carmelo; Grasso, Dario; Maccione, Luca; Ullio, Piero

    2011-01-01

    The latest years have seen steady progresses in WIMP dark matter (DM) searches, with hints of possible signals suggested by both direct and indirect detection experiments. Antiprotons can play a key role validating those interpretations since they are copiously produced by WIMP annihilations in the Galactic halo, and the secondary antiproton background produced by Cosmic Ray (CR) interactions is predicted with fair accuracy and matches the observed spectrum very well. Using the publicly available numerical DRAGON code, we reconsider antiprotons as a tool to constrain DM models discussing its power and limitations. We provide updated constraints on a wide class of annihilating DM models by comparing our predictions against the most up-to-date ap measurements, taking also into account the latest spectral information on the p, He and other CR nuclei fluxes. Doing that, we probe carefully the uncertainties associated to both secondary and DM originated antiprotons, by using a variety of distinctively different as...

  14. The new large-scale international facility for antiproton and ion research in Europe, FAIR

    Energy Technology Data Exchange (ETDEWEB)

    Rosner, Guenther [Facility for Antiprotons and Ion Research (FAIR), Darmstadt (Germany)

    2012-07-01

    Full text: FAIR is currently the largest project in nuclear and particle physics worldwide, with investment costs of 1.6B euro in its first phase. It has been founded by Finland, France, Germany, India, Poland, Romania, Russia, Slovenia and Sweden in Oct. 2010. The facility will provide the international scientific community with a unique and technically innovative particle accelerator system to perform cutting-edge research in the sciences concerned with the basic structure of matter in: nuclear and particle physics, atomic and anti-matter physics, high density plasma physics, and applications in condensed matter physics, biology and the bio-medical sciences. The work horse of FAIR will be a 1.1 km circumference double ring of rapidly cycling 100 and 300 Tm synchrotrons, which will be used to produce high intensity secondary beams of anti-protons and very short-lived radioactive ions. A subsequent suite of cooler and storage rings will deliver anti-proton and heavy-ion beams of unprecedented quality regarding intensity and resolution. Large experimental facilities are presently being prototyped by the APPA, CBM, NuSTAR and PANDA Collaborations to be used by a global community of more than 3000 scientists from 2018. (author)

  15. Density shift and broadening of transition lines in antiprotonic helium

    Science.gov (United States)

    Bakalov; Jeziorski; Korona; Szalewicz; Tchoukova

    2000-03-13

    The density shift and broadening of the transition lines of antiprotonic helium have been evaluated in the impact approximation using an interatomic potential calculated ab initio with the symmetry-adapted perturbation theory. The results help to remove an uncertainty of up to 10 ppm in the laser spectroscopy data on antiprotonic helium and are of importance in experimental tests of bound state QED and CPT invariance.

  16. Sneaky light stop

    Directory of Open Access Journals (Sweden)

    Till Eifert

    2015-04-01

    Full Text Available A light supersymmetric top quark partner (stop with a mass nearly degenerate with that of the standard model (SM top quark can evade direct searches. The precise measurement of SM top properties such as the cross-section has been suggested to give a handle for this ‘stealth stop’ scenario. We present an estimate of the potential impact a light stop may have on top quark mass measurements. The results indicate that certain light stop models may induce a bias of up to a few GeV, and that this effect can hide the shift in, and hence sensitivity from, cross-section measurements. Due to the different initial states, the size of the bias is slightly different between the LHC and the Tevatron. The studies make some simplifying assumptions for the top quark measurement technique, and are based on truth-level samples.

  17. Toward polarized antiprotons: Machine development for spin-filtering experiments at COSY

    CERN Document Server

    Weidemann, C; Stein, H J; Lorentz, B; Bagdasarian, Z; Barion, L; Barsov, S; Bechstedt, U; Bertelli, S; Chiladze, D; Ciullo, G; Contalbrigo, M; Dymov, S; Engels, R; Gaisser, M; Gebel, R; Goslawski, P; Grigoriev, K; Guidoboni, G; Kacharava, A; Kamerdzhiev, V; Khoukaz, A; Kulikov, A; Lehrach, A; Lenisa, P; Lomidze, N; Macharashvili, G; Maier, R; Martin, S; Mchedlishvili, D; Meyer, H O; Merzliakov, S; Mielke, M; Mikirtychiants, M; Mikirtychiants, S; Nass, A; Nikolaev, N N; Oellers, D; Papenbrock, M; Pesce, A; Prasuhn, D; Retzlaff, M; Schleichert, R; Schröer, D; Seyfarth, H; Soltner, H; Statera, M; Steffens, E; Stockhorst, H; Ströher, H; Tabidze, M; Tagliente, G; Engblom, P Thörngren; Trusov, S; Valdau, Yu; Vasiliev, A; Wüstner, P

    2014-01-01

    The paper describes the commissioning of the experimental equipment and the machine studies required for the first spin-filtering experiment with protons at a beam kinetic energy of $49.3\\,$MeV in COSY. The implementation of a low-$\\beta$ insertion made it possible to achieve beam lifetimes of $\\tau_{\\rm{b}}=8000\\,$s in the presence of a dense polarized hydrogen storage-cell target of areal density $d_{\\rm t}=(5.5\\pm 0.2)\\times 10^{13}\\,\\mathrm{atoms/cm^{2}}$. The developed techniques can be directly applied to antiproton machines and allow for the determination of the spin-dependent $\\bar{p}p$ cross sections via spin filtering.

  18. Ready to stop

    DEFF Research Database (Denmark)

    Molitoris, Joseph; Dribe, Martin

    2016-01-01

    the Roteman Database for Stockholm, Sweden between 1878 and 1926 to examine the association of socioeconomic status and fertility and the adoption of stopping behaviour during the city's transition. Using piecewise constant hazard models and logistic regression, we find that a clear class pattern arises...... in which the elite were early practitioners of fertility control, followed by the working classes. As the transition unfolded, socioeconomic differences in stopping behaviour disappeared and overall fertility differentials were also minimized, both of them being consistent with patterns observed in rural...

  19. The experiment PANDA: physics with antiprotons at FAIR

    Science.gov (United States)

    Boca, Gianluigi

    2015-05-01

    PANDA is an experiment that will run at the future facility FAIR, Darmstadt, Germany. A high intensity and cooled antiproton beam will collide on a fixed hydrogen or nuclear target covering center-of-mass energies between 2.2 and 5.5 GeV. PANDA addresses various physics aspects from the low energy non-perturbative region towards the perturbative regime of QCD. With the impressive theoretical developments in this field, e.g. lattice QCD, the predictions are becoming more accurate in the course of time. The data harvest with PANDA will, therefore, be an ideal test bench with the aim to provide a deeper understanding of hadronic phenomena such as confinement and the generation of hadron masses. A variety of physics topics will be covered with PANDA, for example: the formation or production of exotic non-qqbar charm meson states connected to the recently observed XYZ spectrum; the study of gluon-rich matter, such as glueballs and hybrids; the spectroscopy of the excited states of strange and charm baryons, their production cross section and their spin correlations; the behaviour of hadrons in nuclear matter; the hypernuclear physics; the electromagnetic proton form factors in the timelike region. The PANDA experiment is designed to achieve the above mentioned physics goals with a setup with the following characteristics: an almost full solid angle acceptance; excellent tracking capabilities with high resolution (1-2 % at 1 GeV/c in the central region); secondary vertex detection with resolution ≈ 100 microns or better; electromagnetic calorimetry for detections of gammas and electrons up to 10 GeV; good particle identification of charge tracks (electrons, muons, pions, kaons, protons); a dedicated interchangeable central apparatus for the hypernuclear physics; detector and data acquisition system capable of working at 20 MHz interaction rate with an intelligent software trigger that can provide maximum flexibility.

  20. Stopping the Bottle

    Science.gov (United States)

    ... is coming later. The next week, eliminate another bottle feeding and provide milk in a cup instead. Try to do this when your baby is sitting at the table in a high chair. Generally, the last bottle to stop should be the nighttime bottle. That ...

  1. One-stop shopping.

    Science.gov (United States)

    Snow, C

    1996-11-25

    The long-term-care industry's new mantras are "continuum of care" and "one-stop shopping." Companies are trying to please consumers who are clamoring for more senior-living options and managed-care organizations that want administratively simple contracting arrangements.

  2. Experiments and practise in beam shaking

    CERN Document Server

    Marriner, J P; Orlov, Y; Poncet, A; van der Meer, S

    1990-01-01

    Storage rings with negative particle beams suffer from neutralisation effects due to ions produced from the residual gas. For antiproton accumulators currently in service, these problems would be very serious were it not for the existence of efficient clearing systems to extract ions and feedback systems to stabilise the p-beam. Similar problems exist for small electron storage rings, because clearing electrodes are often not sufficient to completely eliminate ions trapped in the beam potential well. One antidote, recently further developed at CERN and Fermilab, consists in shaking the beam at a fixed frequency close to one of the betatron side bands of the main beam and close to the bounce frequency of trapped ions. The authors describe the experience gained in applying this method on the CERN and the Fermilab Antiproton Accumulators, and on the CERN 600 MeV electron positron damping ring (EPA).

  3. CERN stop-over for KEK and Fermilab Directors

    CERN Multimedia

    2001-01-01

    En route for a meeting of the International Committee for Future Accelerators, ICFA, held at Germany's DESY laboratory, the Directors of Japan's KEK laboratory and Fermilab in the United States had a stop-over at CERN last Wednesday 7 February. Dr Hirotaka Sugawara, Director General of Japan's high energy physics laboratory, KEK, visited the Antiproton Decelerator, AD. From left to right, Masaki Hori, member of the ASACUSA collaboration, John Eades, contact person for ASACUSA, Dr Hirotaka Sugawara, Werner Pirkl, the PS Division engineer responsible for the Radio Frequency Quadrupole decelerator in the foreground, and Kurt Hübner, CERN's Director of Accelerators. Dr Michael S. Witherell, Director of the Fermi National Accelerator Laboratory, Fermilab, visited construction sites for the LHC, ATLAS, and CMS. He is seen here with a module of the CMS hadronic calorimeter in building 186.

  4. Search for Resonances in the Photoproduction of Proton-Antiproton Pairs

    Energy Technology Data Exchange (ETDEWEB)

    Stokes, Burnham [Florida State Univ., Tallahassee, FL (United States)

    2006-01-01

    Results are reported on the reaction γp → p$\\bar{p}$p with beam energy in the range 4.8-5.5 GeV. The data were collected at the Thomas Jefferson National Accelerator Facility in CLAS experiment E01-017(G6C). The focus of this study is an understanding of the mechanisms of photoproduction of proton-antiproton pairs, and to search for intermediate resonances, both narrow and broad, which decay to p$\\bar{p}$. The total measured cross section in the photon energy range 4.8-5.5 GeV is σ = 33 ± 2 nb. Measurement of the cross section as a function of energy is provided. An upper limit on the production of a narrow resonance state previously observed with a mass of 2.02 GeV/c2 is placed at 0.35 nb. No intermediate resonance states were observed. Meson exchange production appears to dominate the production of the proton-antiproton pairs.

  5. Monte-Carlo simulation of events for (un)polarized Drell-Yan with antiprotons

    CERN Document Server

    Bianconi, A

    2004-01-01

    The complete knowledge of the nucleon spin structure at leading twist requires also addressing the transverse spin distribution of quarks, or transversity, which is yet unexplored because of its chiral-odd nature. Transversity can be best extracted from single-spin asymmetries in fully polarized Drell-Yan processes with antiprotons, where valence contributions are involved anyway. Alternatively, in single-polarized Drell-Yan the transversity happens convoluted with another chiral-odd function, which is likely to be responsible for the well known (and yet unexplained) violation of the Lam-Tung sum rule in the corresponding unpolarized cross section. We present Monte-Carlo simulations for the unpolarized and single-polarized Drell-Yan $\\bar{p} p^{(\\uparrow)} \\to \\mu^+ \\mu^- X$ with antiproton beam energies of 40 and 15 GeV as a test case, in order to estimate the minimum number of events needed to extract the above chiral-odd distributions from future measurements at the HESR ring at GSI. It is important to stu...

  6. ${\\bar D}D$ meson pair production in antiproton-nucleus collisions

    CERN Document Server

    Shyam, R

    2016-01-01

    We study the $\\bar D D$ (${\\bar D}^0 D^0$ and $D^-D^+$) charm meson pair production in antiproton (${\\bar p}$) induced reactions on nuclei at beam energies ranging from threshold to several GeV. Our model is based on an effective Lagrangian approach that has only the baryon-meson degrees of freedom and involves the physical hadron masses. The reaction proceeds via the $t$-channel exchanges of $\\Lambda_c^+$, $\\Sigma_c^+$, and $\\Sigma_c^{++}$ baryons in the initial collision of the antiproton with one of the protons of the target nucleus. The medium effects on the exchanged baryons are included by incorporating in the corresponding propagators, the effective charm baryon masses calculated within a quark-meson coupling (QMC) model. The wave functions of the bound proton have been determined within the QMC model as well as in a phenomenological model where they are obtained by solving the Dirac equation with appropriate scalar and vector potentials. The initial- and final-state distortion effects have been approx...

  7. Has Human Evolution Stopped?

    OpenAIRE

    TEMPLETON, Alan R

    2010-01-01

    It has been argued that human evolution has stopped because humans now adapt to their environment via cultural evolution and not biological evolution. However, all organisms adapt to their environment, and humans are no exception. Culture defines much of the human environment, so cultural evolution has actually led to adaptive evolution in humans. Examples are given to illustrate the rapid pace of adaptive evolution in response to cultural innovations. These adaptive responses have important ...

  8. Optimally Stopped Optimization

    Science.gov (United States)

    Vinci, Walter; Lidar, Daniel A.

    2016-11-01

    We combine the fields of heuristic optimization and optimal stopping. We propose a strategy for benchmarking randomized optimization algorithms that minimizes the expected total cost for obtaining a good solution with an optimal number of calls to the solver. To do so, rather than letting the objective function alone define a cost to be minimized, we introduce a further cost-per-call of the algorithm. We show that this problem can be formulated using optimal stopping theory. The expected cost is a flexible figure of merit for benchmarking probabilistic solvers that can be computed when the optimal solution is not known and that avoids the biases and arbitrariness that affect other measures. The optimal stopping formulation of benchmarking directly leads to a real-time optimal-utilization strategy for probabilistic optimizers with practical impact. We apply our formulation to benchmark simulated annealing on a class of maximum-2-satisfiability (MAX2SAT) problems. We also compare the performance of a D-Wave 2X quantum annealer to the Hamze-Freitas-Selby (HFS) solver, a specialized classical heuristic algorithm designed for low-tree-width graphs. On a set of frustrated-loop instances with planted solutions defined on up to N =1098 variables, the D-Wave device is 2 orders of magnitude faster than the HFS solver, and, modulo known caveats related to suboptimal annealing times, exhibits identical scaling with problem size.

  9. Tourette Syndrome: Help Stop Bullying

    Science.gov (United States)

    ... Past Emails CDC Features Tourette Syndrome: Help Stop Bullying Language: English Español (Spanish) Recommend on Facebook Tweet ... you can increase acceptance by helping to stop bullying of children with TS. Bullying doesn't just ...

  10. Production of fragments and hyperfragments in antiproton-nucleus collisions

    Science.gov (United States)

    Feng, Zhao-Qing

    2016-04-01

    The formation mechanism of fragments with strangeness in collisions of antiprotons on nuclei has been investigated within the Lanzhou quantum molecular dynamics (LQMD) transport model. Production of strange particles in the antiproton-induced nuclear reactions is modeled within the LQMD model, in which all possible reaction channels such as elastic scattering, annihilation, charge exchange, and inelastic scattering in antibaryon-baryon, baryon-baryon, and meson-baryon collisions have been included. A coalescence approach is developed for constructing hyperfragments in phase space. The hyperfragments are formed within the narrower rapidities. It has the advantage of producing heavier hyperfragments and hypernuclides with strangeness s =-2 (double-Λ fragments) and s =1 (Λ ¯ fragments) in antiproton-induced reactions.

  11. Strangeness production and hypernucleus formation in antiproton induced reactions

    CERN Document Server

    Feng, Zhao-Qing

    2015-01-01

    Formation mechanism of fragments with strangeness in collisions of antiprotons on nuclei has been investigated within the Lanzhou quantum molecular dynamics (LQMD) transport approach combined with a statistical model (GEMINI) for describing the decays of excited fragments. Production of strange particles in the antiproton induced nuclear reactions is modeled within the LQMD model, in which all possible reaction channels such as elastic scattering, annihilation, charge exchange and inelastic scattering in antibaryon-baryon, baryon-baryon and meson-baryon collisions have been included. A coalescence approach is developed for constructing hyperfragments in phase space after de-excitation of nucleonic fragments. The combined approach could describe the production of fragments in low-energy antiproton induced reactions. Hyperfragments are formed within the narrower rapidities and lower kinetic energies. It has advantage to produce heavier hyperfragments and hypernuclides with strangeness s=-2 (double-$\\Lambda$ fra...

  12. High-energy antiprotons from old supernova remnants

    CERN Document Server

    Blasi, Pasquale

    2009-01-01

    A recently proposed model (arXiv:0903.2794) explains the rise in energy of the positron fraction measured by the PAMELA satellite in terms of hadronic production of positrons in aged supernova remnants, and acceleration therein. Here we present a preliminary calculation of the anti-proton flux produced by the same mechanism. While the model is consistent with present data, a rise of the antiproton to proton ratio is predicted at high energy, which strikingly distinguishes this scenario from other astrophysical explanations of the positron fraction (like pulsars). We briefly discuss important implications for Dark Matter searches via antimatter.

  13. High-energy antiprotons from old supernova remnants.

    Science.gov (United States)

    Blasi, Pasquale; Serpico, Pasquale D

    2009-08-21

    A recently proposed model explains the rise in energy of the positron fraction measured by the PAMELA satellite in terms of hadronic production of positrons in aged supernova remnants, and acceleration therein. Here we present a preliminary calculation of the antiproton flux produced by the same mechanism. While the model is consistent with present data, a rise of the antiproton to proton ratio is predicted at high energy, which strikingly distinguishes this scenario from other astrophysical explanations of the positron fraction (such as pulsars). We briefly discuss important implications for dark matter searches via antimatter.

  14. Development of narrowband lasers for spectroscopy of antiprotonic atoms

    Directory of Open Access Journals (Sweden)

    Hori M.

    2014-03-01

    Full Text Available We review some lasers developed by the ASACUSA collaboration of CERN, to carry out spectroscopy of antiprotonic helium atoms. These lasers were based on the technique of continuous-wave injection seeding of pulsed lasers. The laser output covered the wavelength regions 264–1154 nm, with peak powers of ~ 1 MW and spectral resolutions of 6–40 MHz. The devices were recently used to measure the transition frequencies of antiprotonic helium atoms to a fractional precision of several parts in ~ 109.

  15. AMS-02 antiprotons from annihilating or decaying dark matter

    Directory of Open Access Journals (Sweden)

    Koichi Hamaguchi

    2015-07-01

    Full Text Available Recently the AMS-02 experiment reported an excess of cosmic ray antiprotons over the expected astrophysical background. We interpret the excess as a signal from annihilating or decaying dark matter and find that the observed spectrum is well fitted by adding contributions from the annihilation or decay of dark matter with mass of O(TeV or larger. Interestingly, Wino dark matter with mass of around 3 TeV, whose thermal relic abundance is consistent with present dark matter abundance, can explain the antiproton excess. We also discuss the implications for the decaying gravitino dark matter with R-parity violation.

  16. Measurement of cosmic-ray antiproton spectrum at solar minimum with a long-duration balloon flight in Antarctica

    CERN Document Server

    Abe, K; Haino, S; Hams, T; Hasegawa, M; Horikoshi, A; Kim, K C; Kusumoto, A; Lee, M H; Makida, Y; Matsuda, S; Matsukawa, Y; Mitchell, J W; Nishimura, J; Nozaki, M; Orito, R; Ormes, J F; Sakai, K; Sasaki, M; Seo, E S; Shinoda, R; Streitmatter, R E; Suzuki, J; Tanaka, K; Thakur, N; Yamagami, T; Yamamoto, A; Yoshida, T; Yoshimura, K

    2011-01-01

    The energy spectrum of cosmic-ray antiprotons has been measured in the range 0.17 to 3.5 GeV, based on 7886 antiprotons collected by the BESS-Polar II instrument during a long-duration flight over Antarctica in the solar minimum period of December 2007 through January 2008. The antiproton spectrum measured by BESS-Polar II shows good consistency with secondary antiproton calculations. Cosmologically primary antiprotons have been searched for by comparing the observed and calculated antiproton spectra. The BESS-Polar II result shows no evidence of primary antiprotons originating from the evaporation of PBH.

  17. Caloric curve of 8 GeV/c negative pion and antiproton + Au reactions

    CERN Document Server

    Ruangma, A; Martin, E; Ramakrishnan, E; Rowland, D J; Veselsky, M; Winchester, E M; Yennello, S J; Beaulieu, L; Hsi, W C; Kwiatkowski, K K; Lefort, T; Viola, V E; Botvina, A; Korteling, R G; Pienkowski, L; Breuer, H; Gushue, S; Remsberg, L P

    2002-01-01

    The relationship between nuclear temperature and excitation energy of hot nuclei formed by 8 GeV/c negative pion and antiproton beams incident on 197Au has been investigated with the ISiS 4-pidetector array at the BNL AGS accelerator. The double-isotope-ratio technique was used to calculate the temperature of the hot system. The two thermometers used (p/d-3He/4He) and (d/t-3He/4He) are in agreement below E*/A ~ 7 MeV when corrected for secondary decay. Comparison of these caloric curves to those from other experiments shows some differences that may be attributable to instrumentation and analysis procedures. The caloric curves from this experiment are also compared with the predictions from the SMM multifragmentation model.

  18. GMSB with Light Stops

    CERN Document Server

    Delgado, Antonio; Quiros, Mariano

    2015-01-01

    Gauge mediated supersymmetry breaking (GMSB) is an elegant mechanism to transmit supersymmetry breaking from the hidden to the MSSM observable sector, which solves the supersymmetric flavor problem. However the smallness of the generated stop mixing requires superheavy stops to reproduce the experimental value of the Higgs mass. Two possible ways out are: i) To extend GMSB by direct superpotential messenger-MSSM Yukawa couplings to generate sizeable mixing, thus reintroducing the flavor problem; ii) To extend the MSSM Higgs sector with singlets and/or triplets providing extra tree-level corrections to the Higgs mass. Singlets will not get any soft mass from GMSB and triplets will contribute to the $\\rho$ parameter which could be an issue. In this paper we explore the second way by introducing extra supersymmetric triplets with hypercharges $Y=(0,\\pm 1)$, with a tree-level custodial $SU(2)_L\\otimes SU(2)_R$ global symmetry in the Higgs sector protecting the $\\rho$ parameter: a supersymmetric generalization of ...

  19. Book Review: Stop, Write!

    Directory of Open Access Journals (Sweden)

    Hans Thulesius

    2013-06-01

    Full Text Available This book on writing grounded theory is intended for the empirical GT researcher who wants to pursue his/her research until publication. It is the first book devoted entirely to such a crucial issue as writing grounded theory. Thus, Stop, Write: Writing Grounded Theory, is a practical book that fills a gap in GT methodology. In the first chapter of the book, Dr. Glaser says, “Stop unending conceptualization, unending data coverage, and unending listening to others who would egg you on with additional data, ideas and/or requirements or simply wait too long”. The book teaches the reader how to actually write a grounded theory by “simply” writing up the sorted memos. This requires efficient sorting that is dealt with in chapter two on Sorting Memos, which includes precious repetition from Theoretical Sensitivity (1978. How writing can be done effectively is outlined in chapter three The Working Paper. Then follows chapter four on how to rework the first draft with the different tasks of editing for language and professionalism. Thereafter Dr. Glaser discusses Writing Problems in chapter five where he gives useful guidance on how to overcome writing blocks and problems with supervisors and dissertation committees. The book also deals with publishing and with collaboration as experienced between Barney Glaser and the cofounder of grounded theory, Anselm Strauss.

  20. Relative Biological Effectiveness and Peripheral Damage of Antiproton Annihilation

    CERN Multimedia

    Kavanagh, J N; Kaiser, F; Tegami, S; Schettino, G; Kovacevic, S; Hajdukovic, D; Welsch, C P; Currell, F J; Toelli, H T; Doser, M; Holzscheiter, M; Herrmann, R; Timson, D J; Alsner, J; Landua, R; Knudsen, H; Comor, J; Moller, S P; Beyer, G

    2002-01-01

    The use of ions to deliver radiation to a body for therapeutic purposes has the potential to be significant improvement over the use of low linear energy transfer (LET) radiation because of the improved energy deposition profile and the enhanced biological effects of ions relative to photons. Proton therapy centers exist and are being used to treat patients. In addition, the initial use of heavy ions such as carbon is promising to the point that new treatment facilities are planned. Just as with protons or heavy ions, antiprotons can be used to deliver radiation to the body in a controlled way; however antiprotons will exhibit additional energy deposition due to annihilation of the antiprotons within the body. The slowing down of antiprotons in matter is similar to that of protons except at the very end of the range beyond the Bragg peak. Gray and Kalogeropoulos estimated the additional energy deposited by heavy nuclear fragments within a few millimeters of the annihilation vertex to be approximately 30 MeV (...

  1. Outer casing of the AA antiproton production target

    CERN Multimedia

    1979-01-01

    The first version of the antiproton production target was a tungsten rod, 11 cm long (actually a row of 11 rods, each 1 cm long) and 3 mm in diameter. The rod was embedded in graphite, pressure-seated into an outer casing made of stainless steel. The casing had fins for forced-air cooling.

  2. The Antiproton Depth Dose Curve Measured with Alanine Detectors

    DEFF Research Database (Denmark)

    Bassler, Niels; Hansen, Johnny Witterseh; Palmans, Hugo;

    2008-01-01

    In this paper we report on the measurement of the antiproton depth dose curve, with alanine detectors. The results are compared with simulations using the particle energy spectrum calculated by FLUKA, and using the track structure model of Hansen et Olsen for conversion of calculated dose...

  3. Light Stops from extra dimensions

    CERN Document Server

    Garcia-Pepin, Mateo

    2016-01-01

    In supersymmetric models the mass of the stops can be considered as the naturalness measure of the theory. Roughly, the lighter the stops are, the more natural the theory is. Both, the absence of supersymmetric signals at experiment and the measurement of the Higgs mass, put scenarios with light stops under increasing tension. I will present a supersymmetry breaking mechanism of the Scherk-Schwarz type that, by introducing extra $SU(2)_L$ triplets in the Higgs sector, is able to generate the correct Higgs mass while keeping stops light.

  4. AA, beam stopper with scintillator screen

    CERN Multimedia

    1980-01-01

    An insertable steel-plate beam stopper was located after nearly a full turn downstream of the injection point. It was fitted with a scintillator screen, a thin plate of Cr-doped alumina, imprinted with a grid and reference points. The screen was illuminated through a window and observed with a highly sensitive TV camera plus image intensifier. This allowed observation of beam position and size of a proton test beam and of the beam from the target, which consisted not only of antiprotons but contained as well electrons, pions and muons of the same momentum.

  5. PROTON STOPPING POWER OF DIFFERENT DENSITY PROFILE PLASMAS

    Directory of Open Access Journals (Sweden)

    David Casas

    2015-04-01

    Full Text Available In this work, the stopping power of a partially ionized plasma is analyzed by means of free electron stopping and bound electron stopping. For the first instance, the RPA dielectric function is used, and for the latter one, an interpolation of high and low projectile velocity formulas is used. The dynamical energy loss of a ion beam inside a plasma is estimated by using an iterative scheme of calculation. The Abel inversion is also applied when we have a plasma with radial symmetry. Finally, we compare our methods with two kind of plasmas. In the first one, we estimate the energy loss in a plasma created by a laser prepulse, whose density is approximated by a piecewise function. For the latter one, a radial electron density is supposed and the stopping is obtained as a function of radius from the calculated lateral points. In both cases, the dependence with the density profile is observed.

  6. Proton Stopping Power of Different Density Profile Plasmas

    CERN Document Server

    Casas, David; Andreev, Alexander A; Schnürer, Matthias; Morales, Roberto

    2014-01-01

    In this work, the stopping power of a partially ionized plasma is analyzed by means of free electron stopping and bound electron stopping. For the first one, the RPA dielectric function is used, and for the latter one, an interpolation of high and low projectile velocity formulas is used. The dynamical energy loss of an ion beam inside a plasma is estimated by using an iterative scheme of calculation. The Abel inversion is also applied when we have a plasma with radial symmetry. Finally, we compare our methods with two kind of plasmas. In the first one, we estimate the energy loss in a plasma created by a laser prepulse, whose density is approximated by a piecewise function. For the latter one, a radial electron density is supposed and the stopping is obtained as function of radius from the calculated lateral points. In both cases, the dependence with the density profile is observed.

  7. Bucket shaking stops bunch dancing in Tevatron

    Energy Technology Data Exchange (ETDEWEB)

    Burov, A.; Tan, C.Y.; /Fermilab

    2011-03-01

    Bunches in Tevatron are known to be longitudinally unstable: their collective oscillations, also called dancing bunches, persist without any signs of decay. Typically, a damper is used to stop these oscillations, but recently, it was theoretically predicted that the oscillations can be stabilized by means of small bucket shaking. Dedicated measurements in Tevatron have shown that this method does stop the dancing. According to predictions of Refs. [2,3], the flattening of the bunch distribution at low amplitudes should make the bunch more stable against LLD. An experiment has been devised to flatten the distribution by modulating the RF phase at the low-amplitude synchrotron frequency for a few degrees of amplitude. These beam studies show that stabilisation really happens. After several consecutive shakings, the dancing disappears and the resulting bunch profile becomes smoother at the top. Although not shown in this report, sometimes a little divot forms at the centre of the distribution. These experiments confirm that resonant RF shaking flattens the bunch distribution at low amplitudes, and the dancing stops.

  8. UDI STOP Femminicidio

    Directory of Open Access Journals (Sweden)

    Giovanna Crivelli

    2014-04-01

    Full Text Available L'UDI, Unione Donne in Italia, ha collaborato con l'Osservatorio dei Processi Comunicativi a un numero monografico della rivista scientifica M@gm@ dal titolo "Violenza maschile e femminicidio". Il numero monografico vuole mettere a disposizione le analisi, l’esperienza e la storia nostra e delle nostre interlocutrici, come contributo al nostro comune lavoro di sensibilizzazione, contrasto alla violenza maschile sulle donne – femminicidio. “UDI STOP femminicidio” è da anni la nostra campagna contro la violenza di genere, la collaborazione con l’Osservatorio dei Processi Comunicativi è parte integrante di questo sforzo. Il primo e dichiarato dei nostri progetti politici è il contrasto alla cultura e al potere ideologico che consente il femminicidio, la subordinazione culturale e sociale, la percezione della donna come oggetto di dominio, la riduzione in schiavitù di tante donne, comprese molte donne prostitute... Sappiamo di non voler tradire una “responsabilità di genere” che deve necessariamente concretizzarsi in tanti “gesti responsabili”, nella lunga pazienza quotidiana che consente la sedimentazione di un cambiamento radicale nelle coscienze. Vogliamo continuare ad essere l’associazione che coniuga insieme la soggettività personale e l'assunzione diretta di responsabilità, della progettualità a lungo termine che non trova “contraddittorio” misurarsi con la solidarietà concreta e quotidiana con le altre donne, nel tentativo di far nascere le nuove maniere di pensare.

  9. Has Human Evolution Stopped?

    Directory of Open Access Journals (Sweden)

    Alan R. Templeton

    2010-07-01

    Full Text Available It has been argued that human evolution has stopped because humans now adapt to their environment via cultural evolution and not biological evolution. However, all organisms adapt to their environment, and humans are no exception. Culture defines much of the human environment, so cultural evolution has actually led to adaptive evolution in humans. Examples are given to illustrate the rapid pace of adaptive evolution in response to cultural innovations. These adaptive responses have important implications for infectious diseases, Mendelian genetic diseases, and systemic diseases in current human populations. Moreover, evolution proceeds by mechanisms other than natural selection. The recent growth in human population size has greatly increased the reservoir of mutational variants in the human gene pool, thereby enhancing the potential for human evolution. The increase in human population size coupled with our increased capacity to move across the globe has induced a rapid and ongoing evolutionary shift in how genetic variation is distributed within and among local human populations. In particular, genetic differences between human populations are rapidly diminishing and individual heterozygosity is increasing, with beneficial health effects. Finally, even when cultural evolution eliminates selection on a trait, the trait can still evolve due to natural selection on other traits. Our traits are not isolated, independent units, but rather are integrated into a functional whole, so selection on one trait can cause evolution to occur on another trait, sometimes with mildly maladaptive consequences.

  10. Has human evolution stopped?

    Science.gov (United States)

    Templeton, Alan R

    2010-07-01

    It has been argued that human evolution has stopped because humans now adapt to their environment via cultural evolution and not biological evolution. However, all organisms adapt to their environment, and humans are no exception. Culture defines much of the human environment, so cultural evolution has actually led to adaptive evolution in humans. Examples are given to illustrate the rapid pace of adaptive evolution in response to cultural innovations. These adaptive responses have important implications for infectious diseases, Mendelian genetic diseases, and systemic diseases in current human populations. Moreover, evolution proceeds by mechanisms other than natural selection. The recent growth in human population size has greatly increased the reservoir of mutational variants in the human gene pool, thereby enhancing the potential for human evolution. The increase in human population size coupled with our increased capacity to move across the globe has induced a rapid and ongoing evolutionary shift in how genetic variation is distributed within and among local human populations. In particular, genetic differences between human populations are rapidly diminishing and individual heterozygosity is increasing, with beneficial health effects. Finally, even when cultural evolution eliminates selection on a trait, the trait can still evolve due to natural selection on other traits. Our traits are not isolated, independent units, but rather are integrated into a functional whole, so selection on one trait can cause evolution to occur on another trait, sometimes with mildly maladaptive consequences.

  11. An antideuteron beam at JHF

    CERN Document Server

    Iazzi, F

    1999-01-01

    The future japanese hadronic machine (JHF) could offer the possibility not only to continue experiments with the antiproton in both the low and high energy ranges but also to start to study the antinuclei physics. In the present paper the production of antinuclei is reviewed and first results of a design for an antideuteron beam line at JHF are reported. Moreover, some particular aspects of the antideuteron physics are discussed together with the basic features of the experimental apparatuses involving an antideuteron beam and the antideuteron annihilation detection.

  12. Spectroscopy of antiprotonic helium atoms and its contribution to the fundamental physical constants

    CERN Document Server

    Hayano, R S

    2010-01-01

    Proceedings of the Japan Academy, Series B Vol. 86 (2010) No. 1 P 1-10 Language: Next Article http://dx.doi.org/10.2183/pjab.86.1 JST.JSTAGE/pjab/86.1 Reviews Spectroscopy of antiprotonic helium atoms and its contribution to the fundamental physical constants Ryugo S. HAYANO1) 1) Department of Physics, The University of Tokyo Released 2010/01/14 Keywords: antiproton, CERN, fundamental physical constants, laser spectroscopy Full Text PDF [1604K] Abstracts References(25) Antiprotonic helium atom, a metastable neutral system consisting of an antiproton, an electron and a helium nucleus, was serendipitously discovered, and has been studied at CERN’s antiproton decelerator facility. Its transition frequencies have recently been measured to nine digits of precision by laser spectroscopy. By comparing these experimental results with three-body QED calculations, the antiproton-to-electron massratio was determined as 1836.152674(5). This result contributed to the CODATA recommended val...

  13. Design and optimisation of low heat load liquid helium cryostat to house cryogenic current comparator in antiproton decelerator at CERN

    Science.gov (United States)

    Lees, A.; Koettig, T.; Fernandes, M.; Tan, J.

    2017-02-01

    The Cryogenic Current Comparator (CCC) is installed in the low-energy Antiproton Decelerator (AD) at CERN to make an absolute measurement of the beam intensity. Operating below 4.2 K, it is based on a superconducting quantum interference device (SQUID) and employs a superconducting niobium shield to supress magnetic field components not linked to the beam current. The AD contains no permanent cryogenic infrastructure so the local continuous liquefaction of helium using a pulse-tube is required; limiting the available cooling power to 0.69 W at 4.2K. Due to the sensitivity of the SQUID to variations in magnetic fields, the CCC is highly sensitive to mechanical vibration which is limited to a minimum by the support systems of the cryostat. This article presents the cooling system of the cryostat and discusses the design challenges overcome to minimise the transmission of vibration to the CCC while operating within the cryogenic limits imposed by the cooling system.

  14. Measurement of the stopping power for 16O in 4He gas

    Science.gov (United States)

    Torresi, D.; Carbone, D.; Cavallaro, M.; Di Pietro, A.; Fernández Garcia, J. P.; Figuera, P.; Fisichella, M.; Lattuada, M.; Zadro, M.

    2016-12-01

    The stopping power for 16O ions in 4He gas from 1 to 31 MeV is measured using an indirect method. The 16O beam of fixed energy entered a scattering chamber filled with 4He gas at different pressures and its residual energy is measured. The stopping power is determined by differentiating the thickness versus residual energy curve. The measured stopping power is compared with those calculated with the codes SRIM and MSTAR.

  15. Secondary electron emission in antiproton-carbon foil collisions

    Energy Technology Data Exchange (ETDEWEB)

    Komaki, K.; Yamazaki, Y.; Kuroki, K. (Inst. of Physics, Coll. of Arts and Sciences, Univ. of Tokyo (Japan)); Andersen, L.H.; Horsdal-Pedersen, E.; Hvelplund, P.; Knudsen, H.; Moeller, S.P.; Uggerhoej, E. (Inst. of Physics, Univ. of Aarhus (Denmark)); Elsener, K. (CERN, Geneva (Switzerland))

    1991-04-01

    Energy spectra of electrons emitted in the forward direction by antiproton and proton bombardments on carbon foil targets were measured in the incident energy region from 500 to 750 keV. In the spectra for antiproton impact, no sharp anticusp, which is expected in place of the cusp in the case of the proton impact, is recognized and a small bump is found at 50 eV below the cusp energy. The spectral profile in the equivelocity region, including smearing out of the anticusp, together with the energy and intensity of the bump, is consistent with a theoretical prediction for wake-riding electrons based on the classical trajectory Monte Carlo method. (orig.).

  16. Dark matter for excess of AMS-02 positrons and antiprotons

    Directory of Open Access Journals (Sweden)

    Chuan-Hung Chen

    2015-07-01

    Full Text Available We propose a dark matter explanation to simultaneously account for the excess of antiproton-to-proton and positron power spectra observed in the AMS-02 experiment while having the right dark matter relic abundance and satisfying the current direct search bounds. We extend the Higgs triplet model with a hidden gauge symmetry of SU(2X that is broken to Z3 by a quadruplet scalar field, rendering the associated gauge bosons stable weakly-interacting massive particle dark matter candidates. By coupling the complex Higgs triplet and the SU(2X quadruplet, the dark matter candidates can annihilate into triplet Higgs bosons each of which in turn decays into lepton or gauge boson final states. Such a mechanism gives rise to correct excess of positrons and antiprotons with an appropriate choice of the triplet vacuum expectation value. Besides, the model provides a link between neutrino mass and dark matter phenomenology.

  17. A Good Statistics Study of Antiproton Interactions with Nuclei

    CERN Multimedia

    2002-01-01

    This experiment extends the study of inclusive pion production and the correlation between pions which result from hadron-nucleus collisions at intermediate and high energies to the antiproton-nucleus system. It is part of a long term systematic search for exotic nuclear phenomena. The correlation data will be used to extract, via pion interferometry, the size and coherence of the annihilation source in nuclei. In addition, the reaction @* + A @A p + A* will be studied to look for structure in the proton spectra which antiproton-nucleus bound states.\\\\ \\\\ The experimental system is based on a flexible, broad range, large acceptance (1~steradian) spectrometer which consists of an 80~cm diameter dipole magnet surrounded with detector arrays. These detectors provide momentum, energy loss, Cerenkov and time of flight information for up to ten ejectiles per event. Momentum resolution varies from 1\\% to 3\\%, depending on energy.

  18. Measurement method of the antiproton gravitational mass using the single electron transistor

    Energy Technology Data Exchange (ETDEWEB)

    Bouchiat, V.; Chardin, G.; Devoret, M.H.; Esteve, D.

    1996-12-31

    We propose a non destructive method to measure the trajectory of a single antiproton in a drift tube using position sensors based on the single electron transistor. We show that this recently developed device has sufficient sensitivity to detect the electric field of a moving charged particle. Comparing the trajectories of antiprotons and H{sup -} ions could allow a reliable determination of the gravitational mass of the antiproton. (authors). 24 refs.

  19. Bubble detector measurements of a mixed radiation field from antiproton annihilation

    CERN Document Server

    Bassler, Niels; Møller, Søren Pape; Petersen, Jørgen B.; Rahbek, Dennis; Uggerhøj, Ulrik I.

    2006-01-01

    In the light of recent progress in the study of the biological potential of antiproton tumour treatment it is important to be able to characterize the neutron intensity arising from antiproton annihilation using simple, compact and reliable detectors. The intensity of fast neutrons from antiproton annihilation on polystyrene has been measured with bubble detectors and a multiplicity has been derived as well as an estimated neutron equivalent dose. Additionally the sensitivity of bubble detectors towards protons was measured.

  20. Antiproton production target of the AA

    CERN Multimedia

    Photographic Service

    1980-01-01

    The target rods were initially of tungsten, later of iridium. Diameters were around 3 mm and the lengths 60-110 mm. The rod is embedded in graphite, pressed into an aluminium body with cooling fins for forced air cooling. The 26 GeV proton beam from the PS was focused to the dimension of the rod. To aim precisely at its centre, the target was fitted with a scintillator screen, with circles at every 5 mm radius. Both scintillator and target had to stand pulses of 1.4E13 protons every 4.8 s, without interruption for many months.

  1. Selected Papers on Low-Energy Antiprotons and Possible Applications

    Energy Technology Data Exchange (ETDEWEB)

    Noble, Robert [Fermilab

    1998-09-19

    The only realistic means by which to create a facility at Fermilab to produce large amounts of low energy antiprotons is to use resources which already exist. There is simply too little money and manpower at this point in time to generate new accelerators on a time scale before the turn of the century. Therefore, innovation is required to modify existing equipment to provide the services required by experimenters.

  2. Antiprotons from dark matter annihilation in the Galaxy. Astrophysical uncertainties

    Energy Technology Data Exchange (ETDEWEB)

    Evoli, Carmelo [Chinese Academy of Sciences, Beijing (China). National Astronomical Observatories; Cholis, Ilias; Ullio, Piero [SISSA, Sezione di Trieste (Italy); INFN, Sezione di Trieste (Italy); Grasso, Dario [INFN, Sezione di Pisa (Italy); Maccione, Luca [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

    2011-08-15

    The latest years have seen steady progresses in WIMP dark matter (DM) searches, with hints of possible signals suggested by both direct and indirect detection experiments. Antiprotons can play a key role validating those interpretations since they are copiously produced by WIMP annihilations in the Galactic halo, and the secondary antiproton background produced by Cosmic Ray (CR) interactions is predicted with fair accuracy and matches the observed spectrum very well. Using the publicly available numerical DRAGON code, we reconsider antiprotons as a tool to constrain DM models discussing its power and limitations. We provide updated constraints on a wide class of annihilating DM models by comparing our predictions against the most up-to-date anti p measurements, taking also into account the latest spectral information on the p, He and other CR nuclei fluxes. Doing that, we probe carefully the uncertainties associated to both secondary and DM originated antiprotons, by using a variety of distinctively different assumptions for the propagation of CRs and for the DM distribution in the Galaxy. We find that the impact of the astrophysical uncertainties on constraining the DM properties can be much stronger, up to a factor of {proportional_to}50, than the one due to uncertainties on the DM distribution ({proportional_to}2-6). Remarkably, even reducing the uncertainties on the propagation parameters derived by local observables, non-local effects can still change DM model constraints even by 50%. Nevertheless, current anti p data place tight constraints on DM models, excluding some of those suggested in connection with indirect and direct searches. Finally we discuss the power of upcoming CR spectral data from the AMS-02 observatory to drastically reduce the uncertainties discussed in this paper and estimate the expected sensitivity of this instrument to some sets of DM models. (orig.)

  3. The Production and Study of Cold Antiprotons and Antihydrogen

    Science.gov (United States)

    2015-08-03

    baryon system . A second goal is to compare the antiproton and proton charge-to-mass ratios to higher precision. All interesting comparisons of the...trap designs now being used in devices that analyze pharmaceuticals and chemical compounds. There are hundreds of scientific citations to the reports... theories (QFT) for which there is a CPT theorem if plausible assump- tions (like causality, locality and Lorentz invariance) are made. Of course

  4. Saturation of low-energy antiproton annihilation on nuclei

    Science.gov (United States)

    Gal, A.; Friedman, E.; Batty, C. J.

    2000-10-01

    Recent measurements of very low-energy (pL0, parallels the recent prediction, for /E<0, that the level widths of /p¯ atoms saturate and, hence, that /p¯ deeply bound atomic states are relatively narrow. Antiproton annihilation cross sections are calculated at pL=57 MeV//c across the periodic table, and their dependence on /Z and /A is classified and discussed with respect to the Coulomb focussing effect at very low energies.

  5. A novel antiproton radial diagnostic based on octupole induced ballistic loss

    CERN Document Server

    Andresen, G B; Bowe, P D; Bray, C C; Butler, E; Cesar, C L; Chapman, S; Charlton, M; Fajans, J; Fujiwara, M C; Funakoshi, R; Gill, D R; Hangst, J S; Hardy, W N; Hayano, R S; Hayden, M E; Humphries, A J; Hydomako, R; Jenkins, M J; Jørgensen, L V; Kurchaninov, L; Lambo, R; Madsen, N; Nolan, P; Olchanski, K; Olin, A; Page, R D; Povilus, A; Pusa, P; Robicheaux, F; Sarid, E; Seif El Nasr, S; Silveira, D M; Storey, J W; Thompson, R I; van der Werf, D P; Wurtele, J S; Yamazaki, Y

    2008-01-01

    We report results from a novel diagnostic that probes the outer radial profile of trapped antiproton clouds. The diagnostic allows us to determine the profile by monitoring the time-history of antiproton losses that occur as an octupole field in the antiproton confinement region is increased. We show several examples of how this diagnostic helps us to understand the radial dynamics of antiprotons in normal and nested Penning-Malmberg traps. Better understanding of these dynamics may aid current attempts to trap antihydrogen atoms.

  6. Single and double ionization of helium by fast antiproton and proton impact

    Energy Technology Data Exchange (ETDEWEB)

    Andersen, L.H.; Hvelplund, P.; Knudsen, H.; Mo-dash-barller, S.P.; Elsener, K.; Rensfelt, K.H.; Uggerho-dash-barj, E.

    1986-10-27

    The first ion-atom--collision data obtained with antiprotons are presented. We measured the single- and double-ionization cross section for 0.5-5-MeV antiprotons and protons colliding with helium. For ion energies above --2 MeV, the single-ionization cross section is the same for protons and antiprotons. However, surprisingly, the double-ionization cross section for antiprotons is approximately a factor of 2 larger than that for protons. The present data constitute a challenge for future theoretical models of charged-particle--atom collisions.

  7. Design of 2-4 GHz Equalizers for the Antiproton Accumulator Stacktail System

    Energy Technology Data Exchange (ETDEWEB)

    Deibele, C.; /Wisconsin U., Madison

    1999-01-01

    The antiproton source at Fermilab requires storage of antiprotons during the production of antiprotons. A fundamental part of the storage process involves stochastic cooling, which requires that the frequency spectrum from the pickups has notches at the revolution frequency and harmonics of the revolution frequency of the antiprotons in the storage ring. A system has been developed for broadband notches but suffers from dispersion. The dispersion inhibits the cooling process and therefore an equalizer is required. The process for designing the equalizers is described and results shown.

  8. Time-dependent density functional calculation of the energy loss of antiprotons colliding with metallic nanoshells

    Energy Technology Data Exchange (ETDEWEB)

    Quijada, M. [Departamento de Fisica de Materiales, Facultad de Quimicas UPV/EHU, Apartado 1072, 20080 San Sebastian (Spain); Donostia International Physics Center DIPC, P. Manuel de Lardizabal 4, 20018 San Sebastian (Spain); Borisov, A.G. [Donostia International Physics Center DIPC, P. Manuel de Lardizabal 4, 20018 San Sebastian (Spain); Universite Paris-Sud, Laboratoire des Collisions Atomiques et Moleculaires (France); CNRS, UMR 8625, Laboratoire des Collisions Atomiques et Moleculaires, LCAM, Batiment 351, UPS-11, Orsay, 91405 Orsay Cedex (France); Muino, R.D. [Donostia International Physics Center DIPC, P. Manuel de Lardizabal 4, 20018 San Sebastian (Spain); Centro de Fisica de Materiales, Centro Mixto CSIC-UPV/EHU, Edificio Korta, Avenida de Tolosa 72, 20018 San Sebastian (Spain)

    2008-06-15

    Time-dependent density functional theory is used to study the interaction between antiprotons and metallic nanoshells. The ground state electronic properties of the nanoshell are obtained in the jellium approximation. The energy lost by the antiproton during the collision is calculated and compared to that suffered by antiprotons traveling in metal clusters. The resulting energy loss per unit path length of material in thin nanoshells is larger than the corresponding quantity for clusters. It is shown that the collision process can be interpreted as the antiproton crossing of two nearly bi-dimensional independent metallic systems. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  9. Interpretation of the cosmic ray positron and antiproton fluxes

    CERN Document Server

    Lipari, Paolo

    2016-01-01

    The spectral shape of cosmic ray positrons and antiprotons has been accurately measured in the broad kinetic energy range 1-350 GeV. In the higher part of this range (E > 30 GeV) the e+ and pbar are both well described by power laws with spectral indices gamma[e+] = 2.77 +-0.02 and gamma[pbar] = 2.78 +- 0.04 that are approximately equal to each other and to the spectral index of protons. In the same energy range the positron/antiproton flux ratio has the approximately constant value 2.04+-0.04, that is consistent with being equal to the ratio e_/pbar calculated for the conventional mechanism of production, where the antiparticles are created as secondaries in the inelastic interactions of primary cosmic rays with interstellar gas. The positron/antiproton ratio at lower energy is significantly higher (reaching the approximate value e+/pbar = 100 for E around 1 GeV), but in the entire energy range 1-350 GeV, the flux ratio is consistent with being equal to ratio of the production rates in the conventional mecha...

  10. Stopping the haemorrhage

    CERN Multimedia

    Anaïs Schaeffer

    2012-01-01

    The cryogenic line, which has been supplying liquid helium to the SM18 Hall area dedicated for tests on radiofrequency cavities and cryomodules for the past 20 years, is currently being dismantled. It will soon be replaced with a state-of-the-art infrastructure with an up to 10 times enhanced performance.   Performing preliminary assembly works on the new cryogenic infrastructure in SM18. Part of the SM18 Hall is devoted to tests on radiofrequency (RF) cavities and cryomodules used for beam acceleration in various CERN experiments and accelerators. Inserted into cryostats and cooled to cryogenic temperatures, these cavities are tested at extreme conditions, which reflect their operating environment. The existing cryogenic infrastructure supplying liquid helium to the six RF tests stations – four vertical cryostats and two bunkers for the horizontal cryomodules – hasn’t quite been delivering the goods. Of the 25 g/s of liquid helium that the cryogenic tank was a...

  11. LHC Availability 2016: Technical Stop 1 to Technical Stop 2

    CERN Document Server

    Todd, Benjamin; Apollonio, Andrea; CERN. Geneva. ATS Department

    2016-01-01

    This document summarises the LHC machine availability for the period of Technical Stop 1 (TS1) to Technical Stop 2 (TS2) in 2016. This period was dedicated to proton physics with a bunch spacing of 25ns. This note has been produced and ratified by the Availability Working Group which has complied fault information for the period in question using the Accelerator Fault Tracker.

  12. LHC Availability 2016: Technical Stop 2 to Technical Stop 3

    CERN Document Server

    Todd, Benjamin; Apollonio, Andrea; CERN. Geneva. ATS Department

    2016-01-01

    This document summarises the LHC machine availability for the period of Technical Stop 2 (TS2) to Technical Stop 3 (TS3) in 2016. This period was dedicated to proton physics with a bunch spacing of 25ns. This note has been produced and ratified by the Availability Working Group which has complied fault information for the period in question using the Accelerator Fault Tracker.

  13. Modified Penning-Malmberg Trap for Storing Antiprotons

    Science.gov (United States)

    Sims, William H.; Martin, James; Lewis, Raymond

    2005-01-01

    A modified Penning-Malmberg trap that could store a small cloud of antiprotons for a relatively long time (weeks) has been developed. This trap is intended for use in research on the feasibility of contemplated future matter/antimatter-annihilation systems as propulsion sources for spacecraft on long missions. This trap is also of interest in its own right as a means of storing and manipulating antiprotons for terrestrial scientific experimentation. The use of Penning-Malmberg traps to store antiprotons is not new. What is new here is the modified trap design, which utilizes state-of-the-art radiofrequency (RF) techniques, including ones that, heretofore, have been used in radio-communication applications but not in iontrap applications. A basic Penning-Malmberg trap includes an evacuated round tube that contains or is surrounded by three or more collinear tube electrodes. A steady axial magnetic field that reaches a maximum at the geometric center of the tube is applied by an external source, and DC bias voltages that give rise to an electrostatic potential that reaches a minimum at the center are applied to the electrodes. The combination of electric and magnetic fields confines the charged particles (ions or electrons) for which it was designed to a prolate spheroidal central region. However, geometric misalignments and the diffusive cooling process prevent the steady fields of a basic Penning- Malmberg trap from confining the particles indefinitely. In the modified Penning-Malmberg trap, the loss of antiprotons is reduced or eliminated by use of a "rotating-wall" RF stabilization scheme that also heats the antiproton cloud to minimize loss by matter/antimatter annihilation. The scheme involves the superposition of a quadrupole electric field that rotates about the cylindrical axis at a suitably chosen radio frequency. The modified Penning-Malmberg trap (see Figure 1) includes several collinear sets of electrodes inside a tubular vacuum chamber. Each set

  14. A Study of the Energy Dependence of the Underlying Event in Proton-Antiproton Collisions

    CERN Document Server

    Aaltonen, Timo Antero; Amerio, Silvia; Amidei, Dante E; Anastassov, Anton Iankov; Annovi, Alberto; Antos, Jaroslav; Apollinari, Giorgio; Appel, Jeffrey A; Arisawa, Tetsuo; Artikov, Akram Muzafarovich; Asaadi, Jonathan A; Ashmanskas, William Joseph; Auerbach, Benjamin; Aurisano, Adam J; Azfar, Farrukh A; Badgett, William Farris; Bae, Taegil; Barbaro-Galtieri, Angela; Barnes, Virgil E; Barnett, Bruce Arnold; Barria, Patrizia; Bartos, Pavol; Bauce, Matteo; Bedeschi, Franco; Behari, Satyajit; Bellettini, Giorgio; Bellinger, James Nugent; Benjamin, Douglas P; Beretvas, Andrew F; Bhatti, Anwar Ahmad; Bland, Karen Renee; Blumenfeld, Barry J; Bocci, Andrea; Bodek, Arie; Bortoletto, Daniela; Boudreau, Joseph Francis; Boveia, Antonio; Brigliadori, Luca; Bromberg, Carl Michael; Brucken, Erik; Budagov, Ioulian A; Budd, Howard Scott; Burkett, Kevin Alan; Busetto, Giovanni; Bussey, Peter John; Butti, Pierfrancesco; Buzatu, Adrian; Calamba, Aristotle; Camarda, Stefano; Campanelli, Mario; Canelli, Florencia; Carls, Benjamin; Carlsmith, Duncan L; Carosi, Roberto; Carrillo Moreno, Salvador; Casal Larana, Bruno; Casarsa, Massimo; Castro, Andrea; Catastini, Pierluigi; Cauz, Diego; Cavaliere, Viviana; Cerri, Alessandro; Cerrito, Lucio; Chen, Yen-Chu; Chertok, Maxwell Benjamin; Chiarelli, Giorgio; Chlachidze, Gouram; Cho, Kihyeon; Chokheli, Davit; Clark, Allan Geoffrey; Clarke, Christopher Joseph; Convery, Mary Elizabeth; Conway, John Stephen; Corbo, Matteo; Cordelli, Marco; Cox, Charles Alexander; Cox, David Jeremy; Cremonesi, Matteo; Cruz Alonso, Daniel; Cuevas Maestro, Javier; Culbertson, Raymond Lloyd; D'Ascenzo, Nicola; Datta, Mousumi; de Barbaro, Pawel; Demortier, Luc M; Marchese, Luigi Marchese; Deninno, Maria Maddalena; Devoto, Francesco; D'Errico, Maria; Di Canto, Angelo; Di Ruzza, Benedetto; Dittmann, Jay Richard; D'Onofrio, Monica; Donati, Simone; Dorigo, Mirco; Driutti, Anna; Ebina, Koji; Edgar, Ryan Christopher; Erbacher, Robin D; Errede, Steven Michael; Esham, Benjamin; Farrington, Sinead Marie; Fernández Ramos, Juan Pablo; Field, Richard D; Flanagan, Gene U; Forrest, Robert David; Franklin, Melissa EB; Freeman, John Christian; Frisch, Henry J; Funakoshi, Yujiro; Galloni, Camilla; Garfinkel, Arthur F; Garosi, Paola; Gerberich, Heather Kay; Gerchtein, Elena A; Giagu, Stefano; Giakoumopoulou, Viktoria Athina; Gibson, Karen Ruth; Ginsburg, Camille Marie; Giokaris, Nikos D; Giromini, Paolo; Glagolev, Vladimir; Glenzinski, Douglas Andrew; Gold, Michael S; Goldin, Daniel; Golossanov, Alexander; Gomez, Gervasio; Gomez-Ceballos, Guillelmo; Goncharov, Maxim T; González López, Oscar; Gorelov, Igor V; Goshaw, Alfred T; Goulianos, Konstantin A; Gramellini, Elena; Grosso-Pilcher, Carla; Guimaraes da Costa, Joao; Hahn, Stephen R; Han, Ji-Yeon; Happacher, Fabio; Hara, Kazuhiko; Hare, Matthew Frederick; Harr, Robert Francis; Harrington-Taber, Timothy; Hatakeyama, Kenichi; Hays, Christopher Paul; Heinrich, Joel G; Herndon, Matthew Fairbanks; Hocker, James Andrew; Hong, Ziqing; Hopkins, Walter Howard; Hou, Suen Ray; Hughes, Richard Edward; Husemann, Ulrich; Hussein, Mohammad; Huston, Joey Walter; Introzzi, Gianluca; Iori, Maurizio; Ivanov, Andrew Gennadievich; James, Eric B; Jang, Dongwook; Jayatilaka, Bodhitha Anjalike; Jeon, Eun-Ju; Jindariani, Sergo Robert; Jones, Matthew T; Joo, Kyung Kwang; Jun, Soon Yung; Junk, Thomas R; Kambeitz, Manuel; Kamon, Teruki; Karchin, Paul Edmund; Kasmi, Azeddine; Kato, Yukihiro; Ketchum, Wesley Robert; Keung, Justin Kien; Kilminster, Benjamin John; Kim, DongHee; Kim, Hyunsoo; Kim, Jieun; Kim, Min Jeong; Kim, Soo Bong; Kim, Shin-Hong; Kim, Young-Kee; Kim, Young-Jin; Kimura, Naoki; Kirby, Michael H; Knoepfel, Kyle James; Kondo, Kunitaka; Kong, Dae Jung; Konigsberg, Jacobo; Kotwal, Ashutosh Vijay; Kreps, Michal; Kroll, IJoseph; Kruse, Mark Charles; Kuhr, Thomas; Kurata, Masakazu; Laasanen, Alvin Toivo; Lammel, Stephan; Lancaster, Mark; Lannon, Kevin Patrick; Latino, Giuseppe; Lee, Hyun Su; Lee, Jaison; Leo, Sabato; Leone, Sandra; Lewis, Jonathan D; Limosani, Antonio; Lipeles, Elliot David; Lister, Alison; Liu, Qiuguang; Liu, Tiehui Ted; Lockwitz, Sarah E; Loginov, Andrey Borisovich; Lucà, Alessandra; Lucchesi, Donatella; Lueck, Jan; Lujan, Paul Joseph; Lukens, Patrick Thomas; Lungu, Gheorghe; Lys, Jeremy E; Lysak, Roman; Madrak, Robyn Leigh; Maestro, Paolo; Malik, Sarah Alam; Manca, Giulia; Manousakis-Katsikakis, Arkadios; Margaroli, Fabrizio; Marino, Christopher Phillip; Matera, Keith; Mattson, Mark Edward; Mazzacane, Anna; Mazzanti, Paolo; McNulty, Ronan; Mehta, Andrew; Mehtala, Petteri; Mesropian, Christina; Miao, Ting; Mietlicki, David John; Mitra, Ankush; Miyake, Hideki; Moed, Shulamit; Moggi, Niccolo; Moon, Chang-Seong; Moore, Ronald Scott; Morello, Michael Joseph; Mukherjee, Aseet; Muller, Thomas; Murat, Pavel A; Mussini, Manuel; Nachtman, Jane Marie; Nagai, Yoshikazu; Naganoma, Junji; Nakano, Itsuo; Napier, Austin; Nett, Jason Michael; Nigmanov, Turgun S; Nodulman, Lawrence J; Noh, Seoyoung; Norniella Francisco, Olga; Oakes, Louise Beth; Oh, Seog Hwan; Oh, Young-do; Okusawa, Toru; Orava, Risto Olavi; Ortolan, Lorenzo; Pagliarone, Carmine Elvezio; Palencia, Jose Enrique; Palni, Prabhakar; Papadimitriou, Vaia; Parker, William Chesluk; Pauletta, Giovanni; Paulini, Manfred; Paus, Christoph Maria Ernst; Phillips, Thomas J; Piacentino, Giovanni M; Pianori, Elisabetta; Pilot, Justin Robert; Pitts, Kevin T; Plager, Charles; Pondrom, Lee G; Poprocki, Stephen; Potamianos, Karolos Jozef; Prokoshin, Fedor; Pranko, Aliaksandr Pavlovich; Ptohos, Fotios K; Punzi, Giovanni; Redondo Fernández, Ignacio; Renton, Peter B; Rescigno, Marco; Rimondi, Franco; Ristori, Luciano; Robson, Aidan; Rodriguez, Tatiana Isabel; Rolli, Simona; Ronzani, Manfredi; Roser, Robert Martin; Rosner, Jonathan L; Ruffini, Fabrizio; Ruiz Jimeno, Alberto; Russ, James S; Rusu, Vadim Liviu; Sakumoto, Willis Kazuo; Sakurai, Yuki; Santi, Lorenzo; Sato, Koji; Saveliev, Valeri; Savoy-Navarro, Aurore; Schlabach, Philip; Schmidt, Eugene E; Schwarz, Thomas A; Scodellaro, Luca; Scuri, Fabrizio; Seidel, Sally C; Seiya, Yoshihiro; Semenov, Alexei; Sforza, Federico; Shalhout, Shalhout Zaki; Shears, Tara G; Shepard, Paul F; Shimojima, Makoto; Shochet, Melvyn J; Shreyber-Tecker, Irina; Simonenko, Alexander V; Sliwa, Krzysztof Jan; Smith, John Rodgers; Snider, Frederick Douglas; Sorin, Maria Veronica; Song, Hao; Stancari, Michelle Dawn; St Denis, Richard Dante; Stentz, Dale James; Strologas, John; Sudo, Yuji; Sukhanov, Alexander I; Suslov, Igor M; Takemasa, Ken-ichi; Takeuchi, Yuji; Tang, Jian; Tecchio, Monica; Teng, Ping-Kun; Thom, Julia; Thomson, Evelyn Jean; Thukral, Vaikunth; Toback, David A; Tokar, Stanislav; Tollefson, Kirsten Anne; Tomura, Tomonobu; Tonelli, Diego; Torre, Stefano; Torretta, Donatella; Totaro, Pierluigi; Trovato, Marco; Ukegawa, Fumihiko; Uozumi, Satoru; Vázquez-Valencia, Elsa Fabiola; Velev, Gueorgui; Vellidis, Konstantinos; Vernieri, Caterina; Vidal Marono, Miguel; Vilar Cortabitarte, Rocio; Vizán Garcia, Jesus Manuel; Vogel, Marcelo; Volpi, Guido; Wagner, Peter; Wallny, Rainer S; Wang, Song-Ming; Waters, David S; Wester, William Carl; Whiteson, Daniel O; Wicklund, Arthur Barry; Wilbur, Scott; Williams, Hugh H; Wilson, Jonathan Samuel; Wilson, Peter James; Winer, Brian L; Wittich, Peter; Wolbers, Stephen A; Wolfe, Homer; Wright, Thomas Roland; Wu, Xin; Wu, Zhenbin; Yamamoto, Kazuhiro; Yamato, Daisuke; Yang, Tingjun; Yang, Un-Ki; Yang, Yu Chul; Yao, Wei-Ming; Yeh, Gong Ping; Yi, Kai; Yoh, John; Yorita, Kohei; Yoshida, Takuo; Yu, Geum Bong; Yu, Intae; Zanetti, Anna Maria; Zeng, Yu; Zhou, Chen; Zucchelli, Stefano

    2015-01-01

    We study charged particle production in proton-antiproton collisions at 300 GeV, 900 GeV, and 1.96 TeV. We use the direction of the charged particle with the largest transverse momentum in each event to define three regions of eta-phi space; toward, away, and transverse. The average number and the average scalar pT sum of charged particles in the transverse region are sensitive to the modeling of the underlying event. The transverse region is divided into a MAX and MIN transverse region, which helps separate the hard component (initial and final-state radiation) from the beam-beam remnant and multiple parton interaction components of the scattering. The center-of-mass energy dependence of the various components of the event are studied in detail. The data presented here can be used to constrain and improve QCD Monte Carlo models, resulting in more precise predictions at the LHC energies of 13 and 14 TeV.

  15. Study of the energy dependence of the underlying event in proton-antiproton collisions

    Science.gov (United States)

    Aaltonen, T.; Albrow, M.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Apollinari, G.; Appel, J. A.; Arisawa, T.; Artikov, A.; Asaadi, J.; Ashmanskas, W.; Auerbach, B.; Aurisano, A.; Azfar, F.; Badgett, W.; Bae, T.; Barbaro-Galtieri, A.; Barnes, V. E.; Barnett, B. A.; Barria, P.; Bartos, P.; Bauce, M.; Bedeschi, F.; Behari, S.; Bellettini, G.; Bellinger, J.; Benjamin, D.; Beretvas, A.; Bhatti, A.; Bland, K. R.; Blumenfeld, B.; Bocci, A.; Bodek, A.; Bortoletto, D.; Boudreau, J.; Boveia, A.; Brigliadori, L.; Bromberg, C.; Brucken, E.; Budagov, J.; Budd, H. S.; Burkett, K.; Busetto, G.; Bussey, P.; Butti, P.; Buzatu, A.; Calamba, A.; Camarda, S.; Campanelli, M.; Canelli, F.; Carls, B.; Carlsmith, D.; Carosi, R.; Carrillo, S.; Casal, B.; Casarsa, M.; Castro, A.; Catastini, P.; Cauz, D.; Cavaliere, V.; Cerri, A.; Cerrito, L.; Chen, Y. C.; Chertok, M.; Chiarelli, G.; Chlachidze, G.; Cho, K.; Chokheli, D.; Clark, A.; Clarke, C.; Convery, M. E.; Conway, J.; Corbo, M.; Cordelli, M.; Cox, C. A.; Cox, D. J.; Cremonesi, M.; Cruz, D.; Cuevas, J.; Culbertson, R.; d'Ascenzo, N.; Datta, M.; de Barbaro, P.; Demortier, L.; Deninno, M.; D'Errico, M.; Devoto, F.; Di Canto, A.; Di Ruzza, B.; Dittmann, J. R.; Donati, S.; D'Onofrio, M.; Dorigo, M.; Driutti, A.; Ebina, K.; Edgar, R.; Elagin, A.; Erbacher, R.; Errede, S.; Esham, B.; Farrington, S.; Fernández Ramos, J. P.; Field, R.; Flanagan, G.; Forrest, R.; Franklin, M.; Freeman, J. C.; Frisch, H.; Funakoshi, Y.; Galloni, C.; Garfinkel, A. F.; Garosi, P.; Gerberich, H.; Gerchtein, E.; Giagu, S.; Giakoumopoulou, V.; Gibson, K.; Ginsburg, C. M.; Giokaris, N.; Giromini, P.; Glagolev, V.; Glenzinski, D.; Gold, M.; Goldin, D.; Golossanov, A.; Gomez, G.; Gomez-Ceballos, G.; Goncharov, M.; González López, O.; Gorelov, I.; Goshaw, A. T.; Goulianos, K.; Gramellini, E.; Grosso-Pilcher, C.; Group, R. C.; Guimaraes da Costa, J.; Hahn, S. R.; Han, J. Y.; Happacher, F.; Hara, K.; Hare, M.; Harr, R. F.; Harrington-Taber, T.; Hatakeyama, K.; Hays, C.; Heinrich, J.; Herndon, M.; Hocker, A.; Hong, Z.; Hopkins, W.; Hou, S.; Hughes, R. E.; Husemann, U.; Hussein, M.; Huston, J.; Introzzi, G.; Iori, M.; Ivanov, A.; James, E.; Jang, D.; Jayatilaka, B.; Jeon, E. J.; Jindariani, S.; Jones, M.; Joo, K. K.; Jun, S. Y.; Junk, T. R.; Kambeitz, M.; Kamon, T.; Karchin, P. E.; Kasmi, A.; Kato, Y.; Ketchum, W.; Keung, J.; Kilminster, B.; Kim, D. H.; Kim, H. S.; Kim, J. E.; Kim, M. J.; Kim, S. H.; Kim, S. B.; Kim, Y. J.; Kim, Y. K.; Kimura, N.; Kirby, M.; Knoepfel, K.; Kondo, K.; Kong, D. J.; Konigsberg, J.; Kotwal, A. V.; Kreps, M.; Kroll, J.; Kruse, M.; Kuhr, T.; Kurata, M.; Laasanen, A. T.; Lammel, S.; Lancaster, M.; Lannon, K.; Latino, G.; Lee, H. S.; Lee, J. S.; Leo, S.; Leone, S.; Lewis, J. D.; Limosani, A.; Lipeles, E.; Lister, A.; Liu, H.; Liu, Q.; Liu, T.; Lockwitz, S.; Loginov, A.; Lucchesi, D.; Lucá, A.; Lueck, J.; Lujan, P.; Lukens, P.; Lungu, G.; Lys, J.; Lysak, R.; Madrak, R.; Maestro, P.; Malik, S.; Manca, G.; Manousakis-Katsikakis, A.; Marchese, L.; Margaroli, F.; Marino, P.; Matera, K.; Mattson, M. E.; Mazzacane, A.; Mazzanti, P.; McNulty, R.; Mehta, A.; Mehtala, P.; Mesropian, C.; Miao, T.; Mietlicki, D.; Mitra, A.; Miyake, H.; Moed, S.; Moggi, N.; Moon, C. S.; Moore, R.; Morello, M. J.; Mukherjee, A.; Muller, Th.; Murat, P.; Mussini, M.; Nachtman, J.; Nagai, Y.; Naganoma, J.; Nakano, I.; Napier, A.; Nett, J.; Neu, C.; Nigmanov, T.; Nodulman, L.; Noh, S. Y.; Norniella, O.; Oakes, L.; Oh, S. H.; Oh, Y. D.; Oksuzian, I.; Okusawa, T.; Orava, R.; Ortolan, L.; Pagliarone, C.; Palencia, E.; Palni, P.; Papadimitriou, V.; Parker, W.; Pauletta, G.; Paulini, M.; Paus, C.; Phillips, T. J.; Piacentino, G.; Pianori, E.; Pilot, J.; Pitts, K.; Plager, C.; Pondrom, L.; Poprocki, S.; Potamianos, K.; Pranko, A.; Prokoshin, F.; Ptohos, F.; Punzi, G.; Redondo Fernández, I.; Renton, P.; Rescigno, M.; Rimondi, F.; Ristori, L.; Robson, A.; Rodriguez, T.; Rolli, S.; Ronzani, M.; Roser, R.; Rosner, J. L.; Ruffini, F.; Ruiz, A.; Russ, J.; Rusu, V.; Sakumoto, W. K.; Sakurai, Y.; Santi, L.; Sato, K.; Saveliev, V.; Savoy-Navarro, A.; Schlabach, P.; Schmidt, E. E.; Schwarz, T.; Scodellaro, L.; Scuri, F.; Seidel, S.; Seiya, Y.; Semenov, A.; Sforza, F.; Shalhout, S. Z.; Shears, T.; Shepard, P. F.; Shimojima, M.; Shochet, M.; Shreyber-Tecker, I.; Simonenko, A.; Sliwa, K.; Smith, J. R.; Snider, F. D.; Song, H.; Sorin, V.; St. Denis, R.; Stancari, M.; Stentz, D.; Strologas, J.; Sudo, Y.; Sukhanov, A.; Suslov, I.; Takemasa, K.; Takeuchi, Y.; Tang, J.; Tecchio, M.; Teng, P. K.; Thom, J.; Thomson, E.; Thukral, V.; Toback, D.; Tokar, S.; Tollefson, K.; Tomura, T.; Tonelli, D.; Torre, S.; Torretta, D.; Totaro, P.; Trovato, M.; Ukegawa, F.; Uozumi, S.; Vázquez, F.; Velev, G.; Vellidis, C.; Vernieri, C.; Vidal, M.; Vilar, R.; Vizán, J.; Vogel, M.; Volpi, G.; Wagner, P.; Wallny, R.; Wang, S. M.; Waters, D.; Wester, W. C.; Whiteson, D.; Wicklund, A. B.; Wilbur, S.; Williams, H. H.; Wilson, J. S.; Wilson, P.; Winer, B. L.; Wittich, P.; Wolbers, S.; Wolfe, H.; Wright, T.; Wu, X.; Wu, Z.; Yamamoto, K.; Yamato, D.; Yang, T.; Yang, U. K.; Yang, Y. C.; Yao, W.-M.; Yeh, G. P.; Yi, K.; Yoh, J.; Yorita, K.; Yoshida, T.; Yu, G. B.; Yu, I.; Zanetti, A. M.; Zeng, Y.; Zhou, C.; Zucchelli, S.; CDF Collaboration

    2015-11-01

    We study charged particle production (pT>0.5 GeV /c , |η |<0.8 ) in proton-antiproton collisions at total center-of-mass energies √{s }=300 GeV , 900 GeV, and 1.96 TeV. We use the direction of the charged particle with the largest transverse momentum in each event to define three regions of η -ϕ space: "toward", "away", and "transverse." The average number and the average scalar pT sum of charged particles in the transverse region are sensitive to the modeling of the "underlying event." The transverse region is divided into a MAX and MIN transverse region, which helps separate the "hard component" (initial and final-state radiation) from the "beam-beam remnant" and multiple parton interaction components of the scattering. The center-of-mass energy dependence of the various components of the event is studied in detail. The data presented here can be used to constrain and improve QCD Monte Carlo models, resulting in more precise predictions at the LHC energies of 13 and 14 TeV.

  16. Study of the energy dependence of the underlying event in proton-antiproton collisions

    Energy Technology Data Exchange (ETDEWEB)

    Nodulman, L.; Aaltonen, T; Albrow, M; Amerio, S.; Amidei, D; Anastassov, A.; Annovi, A; Antos, J; Apollinari, G.; Appel, J A; Arisawa, T

    2015-11-23

    We study charged particle production (p(T) > 0.5 GeV/c, vertical bar eta vertical bar < 0.8) in proton-antiproton collisions at total center-of-mass energies root s = 300 GeV, 900 GeV, and 1.96 TeV. We use the direction of the charged particle with the largest transverse momentum in each event to define three regions of eta - phi space: "toward", "away", and "transverse." The average number and the average scalar pT sum of charged particles in the transverse region are sensitive to the modeling of the "underlying event." The transverse region is divided into a MAX and MIN transverse region, which helps separate the "hard component" (initial and final-state radiation) from the "beam-beam remnant" and multiple parton interaction components of the scattering. The center-of-mass energy dependence of the various components of the event is studied in detail. The data presented here can be used to constrain and improve QCD Monte Carlo models, resulting in more precise predictions at the LHC energies of 13 and 14 TeV.

  17. View of the CERN Antiproton Decelerator (AD) and portrait of Prof. Tommy Eriksson, in charge of the AD machine.

    CERN Multimedia

    Maximilien Brice

    2011-01-01

    The Antiproton Decelerator (AD) is a storage ring at the CERN laboratory in Geneva. It started operation in 2000. It decelerates antiprotons before sending them to several experiments studying antimatter : ALPHA, ASACUSA, ATRAP and ACE.

  18. C-stop production by micro injection moulding

    DEFF Research Database (Denmark)

    Islam, Aminul

    Hearing loss affects human life emotionally, physically, mentally and spiritually. A hearing aid can dramatically improve personal and professional life of man affected by hearing loss and the newly designed product C-Stop can dramatically improve the life a hearing aid. C-Stop is a master piece...... of engineering micro product which integrate many features like beam snapfit, annular snapfit, hinge connection, filter grid, house, lid etc in a single product. All the features are in micro dimensional scale and manufactured by single step of injection moulding. This presentation will cover industrial...

  19. Stopping power of an electron gas with anisotropic temperature

    Science.gov (United States)

    Khelemelia, O. V.; Kholodov, R. I.

    2016-04-01

    A general theory of motion of a heavy charged particle in the electron gas with an anisotropic velocity distribution is developed within the quantum-field method. The analytical expressions for the dielectric susceptibility and the stopping power of the electron gas differs in no way from well-known classic formulas in the approximation of large and small velocities. Stopping power of the electron gas with anisotropic temperature in the framework of the quantum-field method is numerically calculated for an arbitrary angle between directions of the motion of the projectile particle and the electron beam. The results of the numerical calculations are compared with the dielectric model approach.

  20. Gated current integrator for the beam in the RR barrier buckets

    Energy Technology Data Exchange (ETDEWEB)

    A. Cadorn; C. Bhat; J. Crisp

    2003-06-10

    At the Fermilab Recycler Ring (RR), the antiproton (pbar) beam will be stored azimuthally in different segments created by barrier buckets. The beam in each segment may have widely varying intensities. They have developed a gated integrator system to measure the beam intensity in each of the barrier bucket. Here they discuss the design of the system and the results of beam measurements using the integrator.

  1. Evaluation on Geant4 Hadronic Models for Pion Minus, Pion Plus and Neutron Particles as Major Antiproton Annihilation Products

    Science.gov (United States)

    Tavakoli, Mohammad Bagher; Mohammadi, Mohammad Mehdi; Reiazi, Reza; Jabbari, Keyvan

    2015-01-01

    Geant4 is an open source simulation toolkit based on C++, which its advantages progressively lead to applications in research domains especially modeling the biological effects of ionizing radiation at the sub-cellular scale. However, it was shown that Geant4 does not give a reasonable result in the prediction of antiproton dose especially in Bragg peak. One of the reasons could be lack of reliable physic model to predict the final states of annihilation products like pions. Considering the fact that most of the antiproton deposited dose is resulted from high-LET nuclear fragments following pion interaction in surrounding nucleons, we reproduced depth dose curves of most probable energy range of pions and neutron particle using Geant4. We consider this work one of the steps to understand the origin of the error and finally verification of Geant4 for antiproton tracking. Geant4 toolkit version 9.4.6.p01 and Fluka version 2006.3 were used to reproduce the depth dose curves of 220 MeV pions (both negative and positive) and 70 MeV neutrons. The geometry applied in the simulations consist a 20 × 20 × 20 cm3 water tank, similar to that used in CERN for antiproton relative dose measurements. Different physic lists including Quark-Gluon String Precompound (QGSP)_Binary Cascade (BIC)_HP, the recommended setting for hadron therapy, were used. In the case of pions, Geant4 resulted in at least 5% dose discrepancy between different physic lists at depth close to the entrance point. Even up to 15% discrepancy was found in some cases like QBBC compared to QGSP_BIC_HP. A significant difference was observed in dose profiles of different Geant4 physic list at small depths for a beam of pions. In the case of neutrons, large dose discrepancy was observed when LHEP or LHEP_EMV lists were applied. The magnitude of this dose discrepancy could be even 50% greater than the dose calculated by LHEP (or LHEP_EMV) at larger depths. We found that effect different Geant4 physic list in

  2. Evaluation on Geant4 Hadronic Models for Pion Minus, Pion Plus and Neutron Particles as Major Antiproton Annihilation Products.

    Science.gov (United States)

    Tavakoli, Mohammad Bagher; Mohammadi, Mohammad Mehdi; Reiazi, Reza; Jabbari, Keyvan

    2015-01-01

    Geant4 is an open source simulation toolkit based on C++, which its advantages progressively lead to applications in research domains especially modeling the biological effects of ionizing radiation at the sub-cellular scale. However, it was shown that Geant4 does not give a reasonable result in the prediction of antiproton dose especially in Bragg peak. One of the reasons could be lack of reliable physic model to predict the final states of annihilation products like pions. Considering the fact that most of the antiproton deposited dose is resulted from high-LET nuclear fragments following pion interaction in surrounding nucleons, we reproduced depth dose curves of most probable energy range of pions and neutron particle using Geant4. We consider this work one of the steps to understand the origin of the error and finally verification of Geant4 for antiproton tracking. Geant4 toolkit version 9.4.6.p01 and Fluka version 2006.3 were used to reproduce the depth dose curves of 220 MeV pions (both negative and positive) and 70 MeV neutrons. The geometry applied in the simulations consist a 20 × 20 × 20 cm(3) water tank, similar to that used in CERN for antiproton relative dose measurements. Different physic lists including Quark-Gluon String Precompound (QGSP)_Binary Cascade (BIC)_HP, the recommended setting for hadron therapy, were used. In the case of pions, Geant4 resulted in at least 5% dose discrepancy between different physic lists at depth close to the entrance point. Even up to 15% discrepancy was found in some cases like QBBC compared to QGSP_BIC_HP. A significant difference was observed in dose profiles of different Geant4 physic list at small depths for a beam of pions. In the case of neutrons, large dose discrepancy was observed when LHEP or LHEP_EMV lists were applied. The magnitude of this dose discrepancy could be even 50% greater than the dose calculated by LHEP (or LHEP_EMV) at larger depths. We found that effect different Geant4 physic list in

  3. Probing Light Stops with Stoponium

    CERN Document Server

    Batell, Brian

    2015-01-01

    We derive new limits on light stops from diboson resonance searches in the $\\gamma\\gamma$, $Z \\gamma$, $ZZ$, $WW$ and $hh$ channels from the first run of the LHC. If the two-body decays of the light stop are mildly suppressed or kinematically forbidden, stoponium bound states will form in $pp$ collisions and subsequently decay via the pair annihilation of the constituent stops to diboson final states, yielding striking resonance signatures. Remarkably, we find that stoponium searches are highly complementary to direct collider searches and indirect probes of light stops such as Higgs coupling measurements. Using an empirical quarkonia potential model and including the first two $S$-wave stoponium states, we find that in the decoupling limit $m_{\\widetilde t_1} \\lesssim 130$ GeV is excluded for any value of the stop mixing angle and heavy stop mass by the combination of the latest resonance searches and the indirect constraints. The $\\gamma \\gamma$ searches are the most complementary to the indirect constraint...

  4. Multiple collision effects on the antiproton production by high energy proton (100 GeV - 1000 GeV)

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, Hiroshi; Powell, J.

    1987-01-01

    Antiproton production rates which take into account multiple collision are calculated using a simple model. Methods to reduce capture of the produced antiprotons by the target are discussed, including geometry of target and the use of a high intensity laser. Antiproton production increases substantially above 150 GeV proton incident energy. The yield increases almost linearly with incident energy, alleviating space charge problems in the high current accelerator that produces large amounts of antiprotons.

  5. Stopping power measurements with the Time-of-Flight (ToF) technique

    Energy Technology Data Exchange (ETDEWEB)

    Fontana, Cristiano L., E-mail: fontana@pd.infn.it [Materials Science & Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Chen, Chien-Hung; Crespillo, Miguel L.; Graham, Joseph T.; Xue, Haizhou [Department of Materials Science & Engineering, University of Tennessee, Knoxville, TN 37996 (United States); Zhang, Yanwen; Weber, William J. [Materials Science & Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Department of Materials Science & Engineering, University of Tennessee, Knoxville, TN 37996 (United States)

    2016-01-01

    A review of measurements of the stopping power of ions in matter is presented along with new measurements of the stopping powers of O, Si, Ti, and Au ions in self-supporting thin foils of SiO{sub 2}, Nb{sub 2}O{sub 5}, and Ta{sub 2}O{sub 5}. A Time-of-Flight system at the Ion Beam Materials Laboratory at the University of Tennessee, Knoxville, was used in transmission geometry in order to reduce experimental uncertainties. The resulting stopping powers show good precision and accuracy and corroborate previously quoted values in the literature. New stopping data are determined.

  6. Second stop and sbottom searches with a stealth stop

    Science.gov (United States)

    Cheng, Hsin-Chia; Li, Lingfeng; Qin, Qin

    2016-11-01

    The top squarks (stops) may be the most wanted particles after the Higgs boson discovery. The searches for the lightest stop have put strong constraints on its mass. However, there is still a search gap in the low mass region if the spectrum of the stop and the lightest neutralino is compressed. In that case, it may be easier to look for the second stop since naturalness requires both stops to be close to the weak scale. The current experimental searches for the second stop are based on the simplified model approach with the decay modes {overset{˜ }{t}}_2to {overset{˜ }{t}}_1Z and {overset{˜ }{t}}_2to {overset{˜ }{t}}_1h . However, in a realistic supersymmetric spectrum there is always a sbottom lighter than the second stop, hence the decay patterns are usually more complicated than the simplified model assumptions. In particular, there are often large branching ratios of the decays {overset{˜ }{t}}_2to {overset{˜ }{b}}_1W and {overset{˜ }{b}}_1to {overset{˜ }{t}}_1W as long as they are open. The decay chains can be even more complex if there are intermediate states of additional charginos and neutralinos in the decays. By studying several MSSM benchmark models at the 14 TeV LHC, we point out the importance of the multi- W final states in the second stop and the sbottom searches, such as the same-sign dilepton and multilepton signals, aside from the traditional search modes. The observed same-sign dilepton excesses at LHC Run 1 and Run 2 may be explained by some of our benchmark models. We also suggest that the vector boson tagging and a new kinematic variable may help to suppress the backgrounds and increase the signal significance for some search channels. Due to the complex decay patterns and lack of the dominant decay channels, the best reaches likely require a combination of various search channels at the LHC for the second stop and the lightest sbottom.

  7. Polarizing a stored proton beam by spin-flip?

    Energy Technology Data Exchange (ETDEWEB)

    Oellers, Dieter Gerd Christian

    2010-04-15

    The present thesis discusses the extraction of the electron-proton spin-flip cross-section. The experimental setup, the data analysis and the results are pictured in detail. The proton is described by a QCD-based parton model. In leading twist three functions are needed. The quark distribution, the helicity distribution and the transversity distribution. While the first two are well-known, the transversity distribution is largely unknown. A self-sufficient measurement of the transversity is possible in double polarized proton-antiproton scattering. This rises the need of a polarized antiproton beam. So far spin filtering is the only tested method to produce a polarized proton beam, which may be capable to hold also for antiprotons. In-situ polarization build-up of a stored beam either by selective removal or by spin-flip of a spin-(1)/(2) beam is mathematically described. A high spin-flip cross-section would create an effective method to produce a polarized antiproton beam by polarized positrons. Prompted by conflicting calculations, a measurement of the spin-flip cross-section in low-energy electron-proton scattering was carried out. This experiment uses the electron beam of the electron cooler at COSY as an electron target. The depolarization of the stored proton beam is detected. An overview of the experiment is followed by detailed descriptions of the cycle setup, of the electron target and the ANKE silicon tracking telescopes acting as a beam polarimeter. Elastic protondeuteron scattering is the analyzing reaction. The event selection is depicted and the beam polarization is calculated. Upper limits of the two electron-proton spin-flip cross-sections {sigma} {sub parallel} and {sigma} {sub perpendicular} {sub to} are deduced using the likelihood method. (orig.)

  8. Bubble detector measurements of a mixed radiation field from antiproton annihilation

    DEFF Research Database (Denmark)

    Bassler, Niels; Knudsen, Helge; Møller, Søren Pape;

    2006-01-01

    In the light of recent progress in the study of the biological potential of antiproton tumour treatment it is important to be able to characterize the neutron intensity arising from antiproton annihilation using simple, compact and reliable detectors. The intensity of fast neutrons from antiproto...

  9. Squid based beam current meter

    Energy Technology Data Exchange (ETDEWEB)

    Kuchnir, M.

    1983-11-25

    A SQUID based beam current meter has the capability of measuring the current of a beam with as little as 30 x 155 antiprotons (with a signal to noise ratio of 2). If low noise dc current is used to cancel most of the beam or an up-down counter is used to count auto-resets this sensitivity will be available at any time in the acumulation process. This current meter will therefore be a unique diagnostic tool for optimizing the performance of several Tev I components. Besides requiring liquid helium it seems that its only drawback is not to follow with the above sensitivity a sudden beam change larger than 16 ..mu..A, something that could be done using a second one in a less sensitive configuration.

  10. Discriminating between antihydrogen and mirror-trapped antiprotons in a minimum-B trap

    CERN Document Server

    Amole, C; Ashkezari, M D; Baquero-Ruiz, M; Bertsche, W; Butler, E; Cesar, C L; Chapman, S; Charlton, M; Deller, A; Eriksson, S; Fajans, J; Friesen, T; Fujiwara, M C; Gill, D R; Gutierrez, A; Hangst, J S; Hardy, W N; Hayden, M E; Humphries, A J; Hydomako, R; Kurchaninov, L; Jonsell, S; Madsen, N; Menary, S; Nolan, P; Olchanski, K; Olin, A; Povilus, A; Pusa, P; Robicheaux, F; Sarid, E; Silveira, D M; So, C; Storey, J W; Thompson, R I; van der Werf, D P; Wurtele, J S

    2012-01-01

    Recently, antihydrogen atoms were trapped at CERN in a magnetic minimum (minimum-B) trap formed by superconducting octupole and mirror magnet coils. The trapped antiatoms were detected by rapidly turning off these magnets, thereby eliminating the magnetic minimum and releasing any antiatoms contained in the trap. Once released, these antiatoms quickly hit the trap wall, whereupon the positrons and antiprotons in the antiatoms annihilated. The antiproton annihilations produce easily detected signals; we used these signals to prove that we trapped antihydrogen. However, our technique could be confounded by mirror-trapped antiprotons, which would produce seemingly-identical annihilation signals upon hitting the trap wall. In this paper, we discuss possible sources of mirror-trapped antiprotons and show that antihydrogen and antiprotons can be readily distinguished, often with the aid of applied electric fields, by analyzing the annihilation locations and times. We further discuss the general properties of antipr...

  11. Extra Low ENergy Antiproton (ELENA) ring and its Transfer Lines: Design Report

    CERN Document Server

    Alanzeau, C; Angoletta, M E; Baillie, J; Barna, D; Bartmann, W; Belochitskii, P; Borburgh, J; Breuker, H; Butin, F; Buzio, M; Capatina, O; Carli, C; Carlier, E; Cattin, M; Dobers, T; Chiggiato, P; Ducimetiere, L; Eriksson, T; Fedemann, S; Fowler, T; Froeschl, R; Gebel, R; Gilbert, N; Hancock, S; Harasimowicz, J; Hori, M; Jorgensen, L V; Kersevan, R; Kuchler, D; Lacroix, J M; LeGodec, G; Lelong, P; Lopez-Hernandez, L; Maury, S; Molendijk, J; Morand, B; Newborough, A; Nisbet, D; Nosych, A; Oelert, W; Paoluzzi, M; Pasinelli, S; Pedersen, F; Perini, D; Puccio, B; Sanchez-Quesada, J; Schoerling, D; Sermeus, L; Soby, L; Timmins, M; Tommasini, D; Tranquille, G; Vanbavinckhove, G; Vorozhtsov, A; Welsch, C; Zickler, T

    2014-01-01

    This Report gives a full description of the ELENA Ring to be built within the circumference of the Antiproton Decelarator (AD) Ring, in Building 193 at CERN. The ELENA ring will further decelerate the antiprotons coming from the AD at the momentum of 100 MeV/c down to 13.7 MeV/c, which corresponds to the kinetic energy of 100 keV before extracting to the physics experiments in the same building. The history of such an extra low energy antiproton ring at CERN goes a long way back, and even to the Decelerator’s previous incarnation, the Low Energy Antiproton Ring (LEAR), which came into operation in 1983. Already at that time, there were physics’ requests to further decelerate the antiprotons expected from LEAR by proposals for ELENA. Appendix I illustrates the cover pages of two such CERN documents from 1982.

  12. Beam Performance and Luminosity Limitations in the High-Energy Storage Ring (HESR)

    CERN Document Server

    Lehrach, A; Hinterberger, F; Maier, R; Prasuhn, D

    2006-01-01

    The High-Energy Storage Ring (HESR) of the future International Facility for Antiproton and Ion Research (FAIR) at GSI in Darmstadt is planned as an antiproton synchrotron and storage ring in the momentum range from 1.5 to 15 GeV/c. An important feature of this new facility is the combination of phase space cooled beams with dense internal targets (e.g. pellet targets), resulting in demanding beam parameter of two operation modes: high luminosity mode with peak luminosities up to 2*10^32 cm-2 s-1, and high resolution mode with a momentum spread down to 10^-5, respectively. To reach these beam parameters very powerful phase space cooling is needed, utilizing high-energy electron cooling and high-bandwidth stochastic cooling. The effect of beam-target scattering and intra-beam interaction is investigated in order to study beam equilibria and beam losses for the two different operation modes.

  13. Beam performance and luminosity limitations in the high-energy storage ring (HESR)

    Science.gov (United States)

    Lehrach, A.; Boine-Frankenheim, O.; Hinterberger, F.; Maier, R.; Prasuhn, D.

    2006-06-01

    The high-energy storage ring (HESR) of the future International Facility for Antiproton and Ion Research (FAIR) at GSI in Darmstadt is planned as an antiproton synchrotron storage ring in the momentum range 1.5-15 GeV/ c. An important feature of this new facility is the combination of phase space cooled beams and dense internal targets (e.g. pellet targets), which results in demanding beam parameter requirements for two operation modes: high luminosity mode with peak luminosities to 2×10 32 cm -2 s -1, and high-resolution mode with a momentum spread down to 10 -5. To reach these beam parameters one needs a very powerful phase space cooling, utilizing high-energy electron cooling and high-bandwidth stochastic cooling. The effects of beam-target scattering and intra-beam interaction are investigated in order to study beam equilibria and beam losses for the two different operation modes.

  14. AMS results on positrons and antiprotons in cosmic rays

    Science.gov (United States)

    Kounine, Andrei; AMS Collaboration

    2017-01-01

    AMS-02 is a particle physics detector collecting data on the International Space Station since May 2011. Precision measurements of charged cosmic ray particles have been performed by AMS using a data sample of 85 billion cosmic ray events collected during the first five years of operations on the Station. The latest AMS results on the fluxes and flux ratios of the cosmic ray particles are presented with the emphasis on the measurements of positrons and antiprotons. They show unique features that require accurate theoretical interpretation as to their origin, be it from dark matter collisions or new astrophysical sources. On behalf of AMS.

  15. The antiproton depth–dose curve measured with alanine detectors

    CERN Document Server

    Bassler, Niels; Palmans, Hugo; Holzscheiter, Michael H; Kovacevic, Sandra

    2008-01-01

    n this paper we report on the measurement of the antiproton depth–dose curve, with alanine detectors. The results are compared with simulations using the particle energy spectrum calculated by FLUKA, and using the track structure model of Hansen and Olsen for conversion of calculated dose into response. A good agreement is observed between the measured and calculated relative effectiveness although an underestimation of the measured values beyond the Bragg-peak remains unexplained. The model prediction of response of alanine towards heavy charged particles encourages future use of the alanine detectors for dosimetry of mixed radiation fields.

  16. Proton-Proton and Proton-Antiproton Colliders

    Science.gov (United States)

    Scandale, Walter

    2015-02-01

    In the last five decades, proton-proton and proton-antiproton colliders have been the most powerful tools for high energy physics investigations. They have also deeply catalyzed innovation in accelerator physics and technology. Among the large number of proposed colliders, only four have really succeeded in becoming operational: the ISR, the SppbarS, the Tevatron and the LHC. Another hadron collider, RHIC, originally conceived for ion-ion collisions, has also been operated part-time with polarized protons. Although a vast literature documenting them is available, this paper is intended to provide a quick synthesis of their main features and key performance.

  17. Proton-Proton and Proton-Antiproton Colliders

    CERN Document Server

    Scandale, Walter

    2014-01-01

    In the last five decades, proton–proton and proton–antiproton colliders have been the most powerful tools for high energy physics investigations. They have also deeply catalyzed innovation in accelerator physics and technology. Among the large number of proposed colliders, only four have really succeeded in becoming operational: the ISR, the SppbarS, the Tevatron and the LHC. Another hadron collider, RHIC, originally conceived for ion–ion collisions, has also been operated part-time with polarized protons. Although a vast literature documenting them is available, this paper is intended to provide a quick synthesis of their main features and key performance.

  18. Understanding Possible Proton-Antiproton Enhancement Observed by BES Collaboration

    Institute of Scientific and Technical Information of China (English)

    GAO Chong-Shou; ZHU Shi-Lin

    2004-01-01

    We comment on the quantum numbers and decay channels of the proton-antiproton enhancement observed by BES Collaboration. Based on the general symmetry consideration and available experimental information, we suggest that the quantum number of this possible signal is very likely to be JPC = 0-+, IG = O+, which cannot decay into final states π+π-, 2π0, KK, 3π. Besides its dissociation into pp, the other important mesonic decay modes could be ηππ, η'ππ, ηηη, 4π, KKπ, ηKK, KKππ, 6π. Experimental search of this signal in these meson final states is strongly called for.

  19. FAIR: The accelerator facility for antiproton and ion research

    Energy Technology Data Exchange (ETDEWEB)

    Sharkov, Boris [FAIR JCR GSI, Darmstad (Germany)

    2010-07-01

    This presentation outlines the current status of the facility for antiproton and ion research (FAIR). It is expected that the actual construction of the facility will commence in 2010 as the project has raised more than one billion euro in funding. The sequence and scope of the construction of the accelerator modules in accordance with modularized start version are described. Outstanding research opportunities offered by the modularized start version for all scientific FAIR communities from early on will allow to bridge the time until FAIR's completion with a world-leading research program. The green paper outlining a realistic path to achieve this goal is discussed.

  20. Antiprotonic potentials from global fits to the PS209 data

    Science.gov (United States)

    Friedman, E.; Gal, A.

    2004-01-01

    The experimental results for strong interaction effects in antiprotonic atoms by the PS209 collaboration consist of high quality data for several sequences of isotopes along the periodic table. Global analysis of these data in terms of a p¯-nucleus optical potential achieves good description of the data using a s-wave finite-range p¯N interaction. Equally good fits are also obtained with a poorly-defined zero-range potential containing a p-wave term.

  1. Stop searches in flavourful supersymmetry

    Science.gov (United States)

    Crivellin, Andreas; Haisch, Ulrich; Tunstall, Lewis C.

    2016-09-01

    Natural realisations of supersymmetry require light stops {tilde{t}}_1 , making them a prime target of LHC searches for physics beyond the Standard Model. Depending on the kinematic region, the main search channels are {tilde{t}}_1to t{tilde{χ}}_1^0 , {tilde{t}}_1to W b{tilde{χ}}_1^0 and {tilde{t}}_1to c{tilde{χ}}_1^0 . We first examine the interplay of these decay modes with {tilde{c}}_1to c{tilde{χ}}_1^0 in a model-independent fashion, revealing that a large parameter space region with stop mass values {m_{tilde{t}}}{_1} up to 530 GeV is excluded for any {tilde{t}}_1to c{tilde{χ}}_1^0 branching ratio by LHC Run I data. The impact of {tilde{c}}_1to c{tilde{χ}}_1^0 decays is further illustrated for scenarios with stop-scharm mixing in the right-handed sector, where it has previously been observed that the stop mass limits can be significantly weakened for large mixing. Our analysis shows that once the {tilde{c}}_1to c{tilde{χ}}_1^0 bounds are taken into account, non-zero stop-scharm mixing can lead to an increase in the allowed parameter space by at most 35%, with large areas excluded for arbitrary mixing.

  2. Antiproton-proton elastic scattering at 3.0 and 4.0 GeV/C; Difusion elastica antiproton-proton a 3,0 y 4,0 GeV/C

    Energy Technology Data Exchange (ETDEWEB)

    Unamuno, S.

    1965-07-01

    This paper presents the results-obtained in studying the two-prong interactions observed in the Saclay 81 cm hydrogen bubble chamber exposed to the 3.0 and 4.0 GeV/c antiproton beams from CERN Proton-Synchroton. Total elastic cross-sections corresponding to both energies are given. The results are given. The results are compared with those of p-p scaterring at different energies and with those of p-p scattering. Several optical-models, from the simples one (the black disk model) to a rather elaborated, four-parameters model have been applied. These models can explain some of the experimental results but fail in predicting the angular distribution of large angle scattering. (Author)

  3. Stopped nucleons in configuration space

    CERN Document Server

    Bialas, Andrzej; Koch, Volker

    2016-01-01

    In this note, using the colour string model, we study the configuration space distribution of stopped nucleons in heavy-ion collisions. We find that the stopped nucleons from the target and the projectile end up separated from each other by the distance increasing with the collision energy. In consequence, for the center of mass energies larger than 6 or 10 GeV (depending on the details of the model) it appears that the system created is not in thermal and chemical equilibrium, and the net baryon density reached is likely not much higher than that already present in the colliding nuclei.

  4. Stop. Write! Writing Grounded Theory

    Directory of Open Access Journals (Sweden)

    Barney G. Glaser, PhD, Hon. PhD

    2012-06-01

    Full Text Available The message in this book, the dictum in this book, is to stop and write when the Grounded Theory (GT methodology puts you in that ready position. Stop unending conceptualization, unending data coverage, and unending listening to others who would egg you on with additional data, ideas and/or requirements or simply wait too long. I will discuss these ideas in detail. My experience with PhD candidates is that for the few who write when ready, many do not and SHOULD. Simply put, many write-up, but many more should.

  5. Transverse velocity dependence of the proton-antiproton ratio as a signature of the QCD critical point.

    Science.gov (United States)

    Asakawa, M; Bass, S A; Müller, B; Nonaka, C

    2008-09-19

    The presence of a critical point in the QCD phase diagram can deform the trajectories describing the evolution of the expanding fireball in the mu_B-T phase diagram. If the average emission time of hadrons is a function of transverse velocity, as microscopic simulations of the hadronic freeze-out dynamics suggest, the deformation of the hydrodynamic trajectories will change the transverse velocity (beta_T) dependence of the proton-antiproton ratio when the fireball passes in the vicinity of the critical point. An unusual beta_T dependence of the [over]p/p ratio in a narrow beam energy window would thus signal the presence of the critical point.

  6. Stop searches in flavourful supersymmetry

    CERN Document Server

    Crivellin, Andreas; Tunstall, Lewis C.

    2016-01-01

    Natural realisations of supersymmetry require light stops ${\\tilde t}_1$, making them a prime target of LHC searches for physics beyond the Standard Model. Depending on the kinematic region, the main search channels are ${\\tilde t_1}\\to t \\tilde \\chi^0_1$, ${\\tilde t_1}\\to W b \\tilde \\chi^0_1$ and ${\\tilde t_1}\\to c \\tilde \\chi^0_1$. We first examine the interplay of these decay modes with ${\\tilde c_1}\\to c \\tilde \\chi^0_1$ in a model-independent fashion, revealing the existence of large regions in parameter space which are excluded for any ${\\tilde t_1}\\to c \\tilde \\chi^0_1$ branching ratio. This effect is then illustrated for scenarios with stop-scharm mixing in the right-handed sector, where it has previously been observed that the stop mass limits can be significantly weakened for large mixing. Our analysis shows that once the LHC bounds from ${\\tilde c_1}\\to c \\tilde \\chi^0_1$ searches are taken into account, non-zero stop-scharm mixing leads only to a modest increase in the allowed regions of parameter...

  7. In Defence of Thought Stopping

    Science.gov (United States)

    Bakker, Gary Maria

    2009-01-01

    Thought stopping (TS) has a long and established history as an effective mental control technique among the cognitive behavioural therapies (CBT). Recent claims have arisen, particularly from acceptance and mindfulness-based authors, that thought suppression--and therefore TS--is counterproductive. These claims take the syllogistic form: TS is a…

  8. Reparametrizations with given stop data

    DEFF Research Database (Denmark)

    Raussen, Martin

    In [1], we performed a systematic investigation of reparametrizations of continuous paths in a Hausdorff space that relies crucially on a proper understanding of stop data of a (weakly increasing) reparametrization of the unit interval. I am indebted to Marco Grandis (Genova) for pointing out tome...

  9. Reparametrizations with given stop data

    DEFF Research Database (Denmark)

    Raussen, Martin

    2009-01-01

    In [1] we performed a systematic investigation of reparametrizations of continuous paths in a Hausdorff space that relies crucially on a proper understanding of stop data of a (weakly increasing) reprametrizations of the unit interval. I am grateful to Marco Grandis (Genova) for pointing out to me...

  10. Remote Shutoff Stops Runaway Lawnmower

    Science.gov (United States)

    Grambo, Alan A.

    2007-01-01

    In this article, the author describes how electronics students at Central Nine Career Center designed a kill switch circuit to stop a runaway lawnmower. This project is ideal for a career center since the electronics/robotics, small engines and horticulture classes can all work together on their respective parts of the modification, installation…

  11. Stopping Power for Degenerate Electrons

    Energy Technology Data Exchange (ETDEWEB)

    Singleton, Jr., Robert [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-05-16

    This is a first attempt at calculating the BPS stopping power with electron degeneracy corrections. Section I establishes some notation and basic facts. Section II outlines the basics of the calculation, and in Section III contains some brief notes on how to proceed with the details of the calculation. The remaining work for the calculation starts with Section III.

  12. Plagiarism: Can It Be Stopped?

    Science.gov (United States)

    Christensen, G. Jay

    2011-01-01

    Plagiarism can be controlled, not stopped. The more appropriate question to ask is: What can be done to encourage students to "cheat" correctly by doing the assignment the way it was intended? Cheating by college students continues to reach epidemic proportions on selected campuses, as witnessed by the recent episode at Central Florida University,…

  13. Baryon Stopping in Au+Au and p+p collisions at 62 and 200 GeV

    Science.gov (United States)

    Brahms Collaboration; Dalsgaard, Hans Hjersing; BRAHMS Collaboration

    2009-11-01

    BRAHMS has measured rapidity density distributions of protons and antiprotons in both p+p and Au+Au collisions at 62 GeV and 200 GeV. From these distributions the yields of so-called ‘net-protons’, that is the difference between the proton and antiproton yields, can be determined. The rapidity dependence of the net-proton yields from peripheral Au+Au collisions is found to have a similar behaviour to that found for the p+p results, while a quite different rapidity dependence is found for central Au+Au collisions. The net-proton distributions can be used together with model calculations to find the net-baryon yields as a function of rapidity, thus yielding information on the average rapidity loss of beam particles, the baryon transport properties of the medium, and the amount of ‘stopping’ in these collisions.

  14. Stopping power of {sup 1}H and {sup 4}He in lithium niobate

    Energy Technology Data Exchange (ETDEWEB)

    Barradas, N.P., E-mail: nunoni@ctn.ist.utl.pt [Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, Estrada Nacional 10, ao km 139.7, 2695-066 Bobadela LRS (Portugal); Laboratório de Engenharia Nuclear, Instituto Superior Técnico, Universidade de Lisboa, Estrada Nacional 10, ao km 139.7, 2695-066 Bobadela LRS (Portugal); Marques, J.G. [Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, Estrada Nacional 10, ao km 139.7, 2695-066 Bobadela LRS (Portugal); Laboratório de Engenharia Nuclear, Instituto Superior Técnico, Universidade de Lisboa, Estrada Nacional 10, ao km 139.7, 2695-066 Bobadela LRS (Portugal); Alves, E. [Associação Euratom/IST, Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, Lisboa 1049-001 (Portugal)

    2014-08-01

    Highlights: •We measured the stopping power of {sup 1}H in LiNbO{sub 3} between 0.27 and 2.33 MeV. •We measured the stopping power of {sup 4}He in LiNbO{sub 3} between 0.44 and 2.33 MeV. •Good agreement was found with SRIM2012 calculations. -- Abstract: Lithium niobate is an important material for applications in bulk optoelectronics and integrated optics devices. Ion beam analysis methods are often used to study this material. However, to our knowledge a single study has been presented in 1996 on measurement of stopping powers in LiNbO{sub 3} at velocities usual in ion beam analysis, for protons and deuterons near the stopping power maximum. The results were 15% lower than the values calculated from the elemental Li, Nb and O stopping powers then available together with the Bragg rule. In practice, all ion beam analysis studies of LiNbO{sub 3} still use the Bragg rule. We have used a bulk method, previously developed by us and applied successfully to other systems, to determine experimentally the stopping power of lithium niobate for {sup 1}H and {sup 4}He ions in the energy range 0.3–2.3 MeV. The results of our measurements and bulk method analysis are presented and discussed in the context of currently available stopping power calculations.

  15. Non-perturbative measurement of low-intensity charged particle beams

    Science.gov (United States)

    Fernandes, M.; Geithner, R.; Golm, J.; Neubert, R.; Schwickert, M.; Stöhlker, T.; Tan, J.; Welsch, C. P.

    2017-01-01

    Non-perturbative measurements of low-intensity charged particle beams are particularly challenging to beam diagnostics due to the low amplitude of the induced electromagnetic fields. In the low-energy antiproton decelerator (AD) and the future extra low energy antiproton rings at CERN, an absolute measurement of the beam intensity is essential to monitor the operation efficiency. Superconducting quantum interference device (SQUID) based cryogenic current comparators (CCC) have been used for measuring slow charged beams in the nA range, showing a very good current resolution. But these were unable to measure fast bunched beams, due to the slew-rate limitation of SQUID devices and presented a strong susceptibility to external perturbations. Here, we present a CCC system developed for the AD machine, which was optimised in terms of its current resolution, system stability, ability to cope with short bunched beams, and immunity to mechanical vibrations. This paper presents the monitor design and the first results from measurements with a low energy antiproton beam obtained in the AD in 2015. These are the first CCC beam current measurements ever performed in a synchrotron machine with both coasting and short bunched beams. It is shown that the system is able to stably measure the AD beam throughout the entire cycle, with a current resolution of 30 {nA}.

  16. Polarizing a stored proton beam by spin flip?

    CERN Document Server

    Oellers, D; Barsov, S; Bechstedt, U; Benati, P; Bertelli, S; Chiladze, D; Ciullo, G; Contalbrigo, M; Dalpiaz, P F; Dietrich, J; Dolfus, N; Dymov, S; Engels, R; Erven, W; Garishvili, A; Gebel, R; Goslawski, P; Grigoryev, K; Hadamek, H; Kacharava, A; Khoukaz, A; Kulikov, A; Langenberg, G; Lehrach, A; Lenisa, P; Lomidze, N; Lorentz, B; Macharashvili, G; Maier, R; Martin, S; Merzliakov, S; Meshkov, I N; Meyer, H O; Mielke, M; Mikirtychiants, M; Mikirtychiants, S; Nass, A; Nekipelov, M; Nikolaev, N N; Nioradze, M; d'Orsaneo, G; Papenbrock, M; Prasuhn, D; Rathmann, F; Sarkadi, J; Schleichert, R; Smirnov, A; Seyfarth, H; Sowinski, J; Spoelgen, D; Stancari, G; Stancari, M; Statera, M; Steffens, E; Stein, H J; Stockhorst, H; Straatmann, H; Ströher, H; Tabidze, M; Tagliente, G; Engblom, P Thoerngren; Trusov, S; Vasilyev, A; Weidemann, Chr; Welsch, D; Wieder, P; Wüstner, P; Zupranski, P

    2009-01-01

    We discuss polarizing a proton beam in a storage ring, either by selective removal or by spin flip of the stored ions. Prompted by recent, conflicting calculations, we have carried out a measurement of the spin flip cross section in low-energy electron-proton scattering. The experiment uses the cooling electron beam at COSY as an electron target. The measured cross sections are too small for making spin flip a viable tool in polarizing a stored beam. This invalidates a recent proposal to use co-moving polarized positrons to polarize a stored antiproton beam.

  17. Fermilab main injector: High intensity operation and beam loss control

    Science.gov (United States)

    Brown, Bruce C.; Adamson, Philip; Capista, David; Chou, Weiren; Kourbanis, Ioanis; Morris, Denton K.; Seiya, Kiyomi; Wu, Guan Hong; Yang, Ming-Jen

    2013-07-01

    From 2005 through 2012, the Fermilab Main Injector provided intense beams of 120 GeV protons to produce neutrino beams and antiprotons. Hardware improvements in conjunction with improved diagnostics allowed the system to reach sustained operation at 400 kW beam power. Transmission was very high except for beam lost at or near the 8 GeV injection energy where 95% beam transmission results in about 1.5 kW of beam loss. By minimizing and localizing loss, residual radiation levels fell while beam power was doubled. Lost beam was directed to either the collimation system or to the beam abort. Critical apertures were increased while improved instrumentation allowed optimal use of available apertures. We will summarize the improvements required to achieve high intensity, the impact of various loss control tools and the status and trends in residual radiation in the Main Injector.

  18. Stopping power: Effect of the projectile deceleration

    Energy Technology Data Exchange (ETDEWEB)

    Kompaneets, Roman, E-mail: kompaneets@mpe.mpg.de; Ivlev, Alexei V.; Morfill, Gregor E. [Max-Planck-Institut für extraterrestrische Physik, Giessenbachstr. 1, 85748 Garching (Germany)

    2014-11-15

    The stopping force is the force exerted on the projectile by its wake. Since the wake does not instantly adjust to the projectile velocity, the stopping force should be affected by the projectile deceleration caused by the stopping force itself. We address this effect by deriving the corresponding correction to the stopping force in the cold plasma approximation. By using the derived expression, we estimate that if the projectile is an ion passing through an electron-proton plasma, the correction is small when the stopping force is due to the plasma electrons, but can be significant when the stopping force is due to the protons.

  19. Progress in understanding heavy-ion stopping

    Science.gov (United States)

    Sigmund, P.; Schinner, A.

    2016-09-01

    We report some highlights of our work with heavy-ion stopping in the energy range where Bethe stopping theory breaks down. Main tools are our binary stopping theory (PASS code), the reciprocity principle, and Paul's data base. Comparisons are made between PASS and three alternative theoretical schemes (CasP, HISTOP and SLPA). In addition to equilibrium stopping we discuss frozen-charge stopping, deviations from linear velocity dependence below the Bragg peak, application of the reciprocity principle in low-velocity stopping, modeling of equilibrium charges, and the significance of the so-called effective charge.

  20. First circulating beam in the AA

    CERN Multimedia

    1980-01-01

    On 3 July 1980, two years after project authorization, beam circulated for the first time in the AA. It was a 3.56 GeV/c proton test beam. We see an expecting crowd, minutes before the happy event. The persons are too numerous to name them all, but the 3 most prominent ones are at the centre (left to right): Roy Billinge (Joint AA Project Leader, with his hand on the control box), Eifionydd Jones (white shirt), Simon van der Meer (spiritus rector and Joint AA Project Leader). The first antiprotons were injected, made to circulate and cooled soon after, on 14 July 1980.

  1. Understanding Possible Proton-Antiproton Enhancement Observed by BES Collaboration

    Institute of Scientific and Technical Information of China (English)

    GAOChong-Shou; ZHUShi-Lin

    2004-01-01

    We comment on the quantum numbers and decay channels of the proton-antiproton enhancement observed by BES Collaboration. Based on the general symmetry consideration and available experimental information, we suggest that the quantum number of this possible signal is very likely to be JPC=0-+, IG=0+, which cannot decay into final states π+π-, 2π0, K/%-K,3π. Besides its dissociation into p-p, the other important mesonic decay modes could be ηππ,η'ππ,ηηη, 4π, K-Kπ,ηK-K,K-Kππ, 6π. Experimental search of this signal in these meson final states is strongly called for.

  2. Antineutron and antiproton nuclear interactions at very low energies

    Science.gov (United States)

    Friedman, E.

    2014-05-01

    Experimental annihilation cross sections of antineutrons and antiprotons at very low energies are compared. Features of Coulomb focusing are observed for pbar annihilation on protons. Direct comparisons for heavier targets are not straightforward due to lack of overlap between targets and energies of experimental results for pbar and nbar. Nevertheless, the annihilation cross sections for nbar on nuclei cannot be described by an optical potential that fits well all the available data on pbar interactions with nuclei. Comparisons made with the help of this potential reveal in the nbar data features similar to Coulomb focusing. Direct comparisons between nbar and pbar annihilations at very low energies would be possible when pbar cross sections are measured on the same targets and at the same energies as the available cross sections for nbar. Such measurements may be possible in the foreseeable future.

  3. The calcaneo-stop procedure.

    Science.gov (United States)

    Usuelli, F G; Montrasio, U Alfieri

    2012-06-01

    Flexible flatfoot is one of the most common deformities. Arthroereisis procedures are designed to correct this deformity. Among them, the calcaneo-stop is a procedure with both biomechanical and proprioceptive properties. It is designed for pediatric treatment. Results similar to endorthesis procedure are reported. Theoretically the procedure can be applied to adults if combined with other procedures to obtain a stable plantigrade foot, but medium-term follow up studies are missing.

  4. Symposium on Highlights from 14 years of LEAR Physics: "Light Antiprotonic Atoms" by R. Hayano

    CERN Multimedia

    1998-01-01

    Symposium on Highlights from 14 years of LEAR Physics hold at CERN, commemorating the closure of LEAR and giving a topical review of the impact of experiments with low energy antiprotons in their respective fields

  5. Experimental and computational study of the injection of antiprotons into a positron plasma for antihydrogen production

    Energy Technology Data Exchange (ETDEWEB)

    Amole, C.; Capra, A.; Menary, S. [Department of Physics and Astronomy, York University, Toronto, M3J 1P3 Ontario (Canada); Ashkezari, M. D.; Hayden, M. E. [Department of Physics, Simon Fraser University, Burnaby, V5A 1S6 British Columbia (Canada); Baquero-Ruiz, M.; Little, A.; So, C.; Zhmoginov, A. [Department of Physics, University of California, Berkeley, California 94720 (United States); Bertsche, W. [Department of Physics, College of Science, Swansea University, SA2 8PP Swansea (United Kingdom); School of Physics and Astronomy, University of Manchester, M13 9PL Manchester (United Kingdom); Daresbury Laboratory, Cockcroft Institute, WA4 4AD Warrington (United Kingdom); Butler, E. [Physics Department, CERN, CH-1211 Geneva 23 (Switzerland); Cesar, C. L.; Silveira, D. M. [Instituto de Fisica, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941 (Brazil); Charlton, M.; Deller, A.; Eriksson, S.; Isaac, C. A.; Madsen, N.; Napoli, S. C.; Shields, C. R. [Department of Physics, College of Science, Swansea University, SA2 8PP Swansea (United Kingdom); Collaboration: ALPHA Collaboration; and others

    2013-04-15

    One of the goals of synthesizing and trapping antihydrogen is to study the validity of charge-parity-time symmetry through precision spectroscopy on the anti-atoms, but the trapping yield achieved in recent experiments must be significantly improved before this can be realized. Antihydrogen atoms are commonly produced by mixing antiprotons and positrons stored in a nested Penning-Malmberg trap, which was achieved in ALPHA by an autoresonant excitation of the antiprotons, injecting them into the positron plasma. In this work, a hybrid numerical model is developed to simulate antiproton and positron dynamics during the mixing process. The simulation is benchmarked against other numerical and analytic models, as well as experimental measurements. The autoresonant injection scheme and an alternative scheme are compared numerically over a range of plasma parameters which can be reached in current and upcoming antihydrogen experiments, and the latter scheme is seen to offer significant improvement in trapping yield as the number of available antiprotons increases.

  6. Symposium on Highlights from 14 years of LEAR Physics : "Antiproton Mass" by G. Gabrielse

    CERN Multimedia

    1998-01-01

    Symposium on Highlights from 14 years Physics hold at CERN, commemorating the closure of LEAR and giving a topical review of the impact of experiments with low energy antiprotons in their respective fields

  7. Beam manipulation and compression using broadband rf systems in the Fermilab Main Injector and Recycler

    Energy Technology Data Exchange (ETDEWEB)

    G William Foster et al.

    2004-07-09

    A novel method for beam manipulation, compression, and stacking using a broad band RF system in circular accelerators is described. The method uses a series of linear voltage ramps in combination with moving barrier pulses to azimuthally compress, expand, or cog the beam. Beam manipulations can be accomplished rapidly and, in principle, without emittance growth. The general principle of the method is discussed using beam dynamics simulations. Beam experiments in the Fermilab Recycler Ring convincingly validate the concept. Preliminary experiments in the Fermilab Main Injector to investigate its potential for merging two ''booster batches'' to produce high intensity proton beams for neutrino and antiproton production are described.

  8. Omega spectrometer ready for SPS beams

    CERN Multimedia

    1977-01-01

    Two different beams arrive into the Omega magnet: - a tagged photon beam for a charm search - experiment WA4 by the Bonn-CERN-Daresbury-Ecole Polytechnique-Glasgow-Lancaster-Manchester-Orsay-Sheffield Collaboration; - a separated hadron beam, at first for a beam-dump experiment - WA12 by the Birmingham-CERN-Ecole Polytechnique-MPI, Munich-Neuchâtel Collaboration. Beams of either negative or positive pions or kaons, protons or antiprotons, all at an energy around 40 GeV were made to impinge on a copper target where a shower of hadrons was produced and, on occasion, two muons which before detection passed through an iron absorber (not visible here). WA12 was completed in February 1977. At the centre, on top of the superconducting magnet, the hut containing the TV cameras, These observe the particle events occurring in the spark chambers in the magnet below.

  9. Antiproton, positron, and electron imaging with a microchannel plate/phosphor detector

    CERN Document Server

    Andresen, G B; Bowe, P D; Bray, C; Butler, E; Cesar, C L; Chapman, S; Charlton, M; Fajans, J; Fujiwara, M C; Gill, D R; Hangst, J S; Hardy, W N; Hayano, R S; Hayden, M E; Humphries, A J; Hydomako, R; Jørgensen, L V; Kerrigan, S J; Kurchaninov, L; Lambo, R; Madsen, N; Nolan, P; Olchanski, K; Olin, A; Povilus, A; Pusa, P; Sarid, E; Seif El Nasr, S; Silveira, D M; Storey, J W; Thompson, R I; van der Werf, D P; Yamazaki, Y

    2009-01-01

    A microchannel plate (MCP)/phosphor screen assembly has been used to destructively measure the radial profile of cold, confined antiprotons, electrons, and positrons in the ALPHA experiment, with the goal of using these trapped particles for antihydrogen creation and confinement. The response of the MCP to low energy (10-200 eV, <1 eV spread) antiproton extractions is compared to that of electrons and positrons.

  10. First measurement of the antiproton-nucleus annihilation cross section at 125 keV

    CERN Document Server

    Aghai-Khozani, H; Corradini, M; De Salvador, D; Hayano, R; Hori, M; Kobayashi, T; Leali, M; Lodi-Rizzini, E; Mascagna, V; Prest, M; Seiler, D; Soter, A; Todoroki, K; Vallazza, E; Venturelli, L

    2015-01-01

    The first observation of in-flight antiproton-nucleus annihilation at ∼130 keV obtained with the ASACUSA detector has demonstrated that the measurement of the cross section of the process is feasible at such extremely low energies Aghai-Khozani, H., et al., Eur. Phys. J. Plus 127, 55 (2012). Here we present the results of the data analysis with the evaluations of the antiproton annihilation cross sections on carbon, palladium and platinum targets at 125 keV.

  11. Primary populations of metastable antiprotonic $^{4}He$ and $^{3}He$ atoms

    CERN Document Server

    Hori, Masaki; Hayano, R S; Ishikawa, T; Sakuguchi, J; Tasaki, T; Widmann, E; Yamaguchi, H; Torii, H A; Juhász, B; Horváth, D; Yamazaki, T

    2002-01-01

    Initial population distributions of metastable antiprotonic **4He and **3He atoms over principal and angular momentum quantum numbers were investigated using laser spectroscopy. The total fractions of antiprotons captured into the metastable states of the atoms were deduced. Cascade calculations were performed using the measure populations to reproduce the delayed annihilation time spectrum. Results showed agreement between the simulated and measured spectra. (Edited abstract) 30 Refs.

  12. Measurements of the Decays $B^0 \\to \\bar{D}^0\\proton\\antiproton$, $B^0 \\to \\bar{D}^{*0}\\proton\\antiproton$, $B^0 \\to D^{-}\\proton\\antiproton\\pi^+$, and $B^0 \\to D^{*-}\\proton\\antiproton\\pi^+$

    CERN Document Server

    Aubert, B; Bóna, M; Boutigny, D; Couderc, F; Karyotakis, Yu; Lees, J P; Poireau, V; Tisserand, V; Zghiche, A; Graugès-Pous, E; Palano, A; Pappagallo, M; Chen, J C; Qi, N D; Rong, G; Wang, P; Zhu, Y S; Eigen, G; Ofte, I; Stugu, B; Abrams, G S; Battaglia, M; Brown, D N; Button-Shafer, J; Cahn, R N; Charles, E; Day, C T; Gill, M S; Groysman, Y; Jacobsen, R G; Kadyk, J A; Kerth, L T; Kolomensky, Yu G; Kukartsev, G; Lynch, G; Mir, L M; Oddone, P J; Orimoto, T J; Pripstein, M; Roe, N A; Ronan, M T; Wenzel, W A; Barrett, M; Ford, K E; Harrison, T J; Hart, A J; Hawkes, C M; Morgan, S E; Watson, A T; Goetzen, K; Held, T; Koch, H; Lewandowski, B; Pelizaeus, M; Peters, K; Schröder, T; Steinke, M; Boyd, J T; Burke, J P; Cottingham, W N; Walker, D; Çuhadar-Dönszelmann, T; Fulsom, B G; Hearty, C; Knecht, N S; Mattison, T S; McKenna, J A; Khan, A; Kyberd, P; Saleem, M; Teodorescu, L; Blinov, V E; Bukin, A D; Druzhinin, V P; Golubev, V B; Onuchin, A P; Serednyakov, S I; Skovpen, Y I; Solodov, E P; Todyshev, K Y; Best, D S; Bondioli, M; Bruinsma, M; Chao, M; Curry, S; Eschrich, I; Kirkby, D; Lankford, A J; Lund, P; Mandelkern, M A; Mommsen, R K; Röthel, W; Stoker, D P; Abachi, S; Buchanan, C; Foulkes, S D; Gary, J W; Long, O; Shen, B C; Wang, K; Zhang, L; Hadavand, H K; Hill, E J; Paar, H P; Rahatlou, S; Sharma, V; Berryhill, J W; Campagnari, C; Cunha, A; Dahmes, B; Hong, T M; Kovalskyi, D; Richman, J D; Beck, T W; Eisner, A M; Flacco, C J; Heusch, C A; Kroseberg, J; Lockman, W S; Nesom, G; Schalk, T; Schumm, B A; Seiden, A; Spradlin, P; Williams, D C; Wilson, M G; Albert, J; Chen, E; Dvoretskii, A; Hitlin, D G; Narsky, I; Piatenko, T; Porter, F C; Ryd, A; Samuel, A; Andreassen, R; Mancinelli, G; Meadows, B T; Sokoloff, M D; Blanc, F; Bloom, P C; Chen, S; Ford, W T; Hirschauer, J F; Kreisel, A; Nauenberg, U; Olivas, A; Ruddick, W O; Smith, J G; Ulmer, K A; Wagner, S R; Zhang, J; Chen, A; Eckhart, E A; Soffer, A; Toki, W H; Wilson, R J; Winklmeier, F; Zeng, Q; Altenburg, D D; Feltresi, E; Hauke, A; Jasper, H; Spaan, B; Brandt, T; Klose, V; Lacker, H M; Mader, W F; Nogowski, R; Petzold, A; Schubert, J; Schubert, K R; Schwierz, R; Sundermann, J E; Volk, A; Bernard, D; Bonneaud, G R; Grenier, P; Latour, E; Thiebaux, C; Verderi, M; Bard, D J; Clark, P J; Gradl, W; Muheim, F; Playfer, S; Robertson, A I; Xie, Y; Andreotti, M; Bettoni, D; Bozzi, C; Calabrese, R; Cibinetto, G; Luppi, E; Negrini, M; Petrella, A; Piemontese, L; Prencipe, E; Anulli, F; Baldini-Ferroli, R; Calcaterra, A; De Sangro, R; Finocchiaro, G; Pacetti, S; Patteri, P; Peruzzi, I M; Piccolo, M; Rama, M; Zallo, A; Buzzo, A; Capra, R; Contri, R; Lo Vetere, M; Macri, M M; Monge, M R; Passaggio, S; Patrignani, C; Robutti, E; Santroni, A; Tosi, S; Brandenburg, G; Chaisanguanthum, K S; Morii, M; Wu, J; Dubitzky, R S; Marks, J; Schenk, S; Uwer, U; Bhimji, W; Bowerman, D A; Dauncey, P D; Egede, U; Flack, R L; Gaillard, J R; Nash, J A; Nikolich, M B; Panduro-Vazquez, W; Chai, X; Charles, M J; Mallik, U; Meyer, N T; Ziegler, V; Cochran, J; Crawley, H B; Dong, L; Eyges, V; Meyer, W T; Prell, S; Rosenberg, E I; Rubin, A E; Gritsan, A V; Fritsch, M; Schott, G; Arnaud, N; Davier, M; Grosdidier, G; Höcker, A; Le Diberder, F R; Lepeltier, V; Lutz, A M; Oyanguren, A; Pruvot, S; Rodier, S; Roudeau, P; Schune, M H; Stocchi, A; Wang, W F; Wormser, G; Cheng, C H; Lange, D J; Wright, D M; Chavez, C A; Forster, I J; Fry, J R; Gabathuler, E; Gamet, R; George, K A; Hutchcroft, D E; Payne, D J; Schofield, K C; Touramanis, C; Bevan, A J; Di Lodovico, F; Menges, W; Sacco, R; Brown, C L; Cowan, G; Flächer, H U; Hopkins, D A; Jackson, P S; McMahon, T R; Ricciardi, S; Salvatore, F; Davis, C L; Allison, J; Barlow, N R; Barlow, R J; Chia, Y M; Edgar, C L; Kelly, M P; Lafferty, G D; Naisbit, M T; Williams, J C; Yi, J I; Chen, C; Hulsbergen, W D; Jawahery, A; Lae, C K; Roberts, D A; Simi, G; Blaylock, G; Dallapiccola, C; Hertzbach, S S; Li, X; Moore, T B; Saremi, S; Stängle, H; Willocq, S Y; Cowan, R; Koeneke, K; Sciolla, G; Sekula, S J; Spitznagel, M; Taylor, F; Yamamoto, R K; Kim, H; Patel, P M; Potter, C T; Robertson, S H; Lazzaro, A; Lombardo, V; Palombo, F; Bauer, J M; Cremaldi, L; Eschenburg, V; Godang, R; Kroeger, R; Reidy, J; Sanders, D A; Summers, D J; Zhao, H W; Brunet, S; Côté, D; Simard, M; Taras, P; Viaud, F B; Nicholson, H; Cavallo, N; De Nardo, Gallieno; Del Re, D; Fabozzi, F; Gatto, C; Lista, L; Monorchio, D; Piccolo, D; Sciacca, C; Baak, M; Bulten, H; Raven, G; Snoek, H L; Jessop, C P; LoSecco, J M; Allmendinger, T; Benelli, G; Gan, K K; Honscheid, K; Hufnagel, D; Jackson, P D; Kagan, H; Kass, R; Pulliam, T; Rahimi, A M; Ter-Antonian, R; Wong, Q K; Blount, N L; Brau, J E; Frey, R; Igonkina, O; Lu, M; Rahmat, R; Sinev, N B; Strom, D; Strube, J; Torrence, E; Galeazzi, F; Gaz, A; Margoni, M; Morandin, M; Pompili, A; Posocco, M; Rotondo, M; Simonetto, F; Stroili, R; Voci, C; Benayoun, M; Chauveau, J; David, P; Del Buono, L; La Vaissière, C de; Hamon, O; Hartfiel, B L; John, M J J; Leruste, P; Malcles, J; Ocariz, J; Roos, L; Therin, G; Behera, P K; Gladney, L; Panetta, J; Biasini, M; Covarelli, R; Pioppi, M; Angelini, C; Batignani, G; Bettarini, S; Bucci, F; Calderini, G; Carpinelli, M; Cenci, R; Forti, F; Giorgi, M A; Lusiani, A; Marchiori, G; Mazur, M A; Morganti, M; Neri, N; Paoloni, E; Rizzo, G; Walsh, J; Haire, M; Judd, D; Wagoner, D E; Biesiada, J; Danielson, N; Elmer, P; Lau, Y P; Lü, C; Olsen, J; Smith, A J S; Telnov, A V; Bellini, F; Cavoto, G; D'Orazio, A; Di Marco, E; Faccini, R; Ferrarotto, F; Ferroni, F; Gaspero, M; Li Gioi, L; Mazzoni, M A; Morganti, S; Piredda, G; Polci, F; Safai-Tehrani, F; Voena, C; Ebert, M; Schröder, H; Waldi, R; Adye, T; De Groot, N; Franek, B; Olaiya, E O; Wilson, F F; Emery, S; Gaidot, A; Ganzhur, S F; Hamel de Monchenault, G; Kozanecki, Witold; Legendre, M; Mayer, B; Vasseur, G; Yéche, C; Zito, M; Park, W; Purohit, M V; Weidemann, A W; Wilson, J R; Allen, M T; Aston, D; Bartoldus, R; Bechtle, P; Berger, N; Boyarski, A M; Claus, R; Coleman, J P; Convery, M R; Cristinziani, M; Dingfelder, J C; Dong, D; Dorfan, J; Dubois-Felsmann, G P; Dujmic, D; Dunwoodie, W M; Field, R C; Glanzman, T; Gowdy, S J; Graham, M T; Halyo, V; Hast, C; Hrynóva, T; Innes, W R; Kelsey, M H; Kim, P; Kocian, M L; Leith, D W G S; Li, S; Libby, J; Luitz, S; Lüth, V; Lynch, H L; MacFarlane, D B; Marsiske, H; Messner, R; Müller, D R; O'Grady, C P; Ozcan, V E; Perazzo, A; Perl, M; Ratcliff, B N; Roodman, A; Salnikov, A A; Schindler, R H; Schwiening, J; Snyder, A; Stelzer, J; Su, D; Sullivan, M K; Suzuki, K; Swain, S K; Thompson, J M; Vavra, J; Van Bakel, N; Weaver, M; Weinstein, A J R; Wisniewski, W J; Wittgen, M; Wright, D H; Yarritu, A K; Yi, K; Young, C C; Burchat, P R; Edwards, A J; Majewski, S A; Petersen, B A; Roat, C; Wilden, L; Ahmed, S; Alam, M S; Bula, R; Ernst, J A; Jain, V; Pan, B; Saeed, M A; Wappler, F R; Zain, S B; Bugg, W; Krishnamurthy, M; Spanier, S M; Eckmann, R; Ritchie, J L; Satpathy, A; Schilling, C J; Schwitters, R F; Izen, J M; Kitayama, I; Lou, X C; Ye, S; Bianchi, F; Gallo, F; Gamba, D; Bomben, M; Bosisio, L; Cartaro, C; Cossutti, F; Della Ricca, G; Dittongo, S; Grancagnolo, S; Lanceri, L; Vitale, L; Azzolini, V; Martínez-Vidal, F; Banerjee, S; Bhuyan, B; Brown, C M; Fortin, D; Hamano, K; Kowalewski, R V; Nugent, I M; Roney, J M; Sobie, R J; Back, J J; Harrison, P F; Latham, T E; Mohanty, G B; Band, H R; Chen, X; Cheng, B; Dasu, S; Datta, M; Eichenbaum, A M; Flood, K T; Hollar, J J; Johnson, J R; Kutter, P E; Li, H; Liu, R; Mellado, B; Mihályi, A; Mohapatra, A K; Pan, Y; Pierini, M; Prepost, R; Tan, P; Wu, S L; Yu, Z; Neal, H

    2006-01-01

    We present measurements of branching fractions of $B^0$ decays to multi-body final states containing protons, based on 232 million $\\Upsilon(4S)\\to B\\bar{B}$ decays collected with the BaBar detector at the SLAC PEP-II asymmetric-energy $B$ factory. We measure the branching fractions ${\\cal B}(B^0 \\to \\bar{D}^0\\proton\\antiproton)=(1.13\\pm0.06\\pm0.08)\\times 10^{-4}$, ${\\cal B}(B^0 \\to \\bar{D}^{*0}\\proton\\antiproton)=(1.01\\pm0.10\\pm0.09)\\times 10^{-4}$, ${\\cal B}(B^0 \\to D^{-}\\proton\\antiproton\\pi^+)=(3.38\\pm0.14\\pm0.29)\\times 10^{-4}$, and ${\\cal B}(B^0 \\to D^{*-}\\proton\\antiproton\\pi^+)=(4.81\\pm0.22\\pm0.44)\\times 10^{-4}$ where the first error is statistical and the second systematic. We present a search for the charmed pentaquark state, $\\Theta_c(3100)$ observed by H1 and put limits on the branching fraction ${\\cal B} (B^0 \\to \\Theta_c \\antiproton\\pi^+)\\times{\\cal B}(\\Theta_c \\to D^{*-}\\proton)<14\\times10^{-6}$ and ${\\cal B}(B^0 \\to \\Theta_c \\antiproton\\pi^+)\\times{\\cal B}(\\Theta_c\\to D^-\\proton)<9\\time...

  13. Stopping of Ships Equipped with Azipods

    Directory of Open Access Journals (Sweden)

    Jacek Nowicki

    2014-09-01

    Full Text Available The paper contains a description of different possibilities of stopping a large ship equipped with azipods. The model tests were carried out to compare the effectiveness of stopping the ship using the different methods. The ship model used in stopping tests reproduces a large LNG carrier of capacity ~150 000 m3

  14. Beam Loss Control for the Fermilab Main Injector

    CERN Document Server

    Brown, Bruce C

    2013-01-01

    From 2005 through 2012, the Fermilab Main Injector provided intense beams of 120 GeV protons to produce neutrino beams and antiprotons. Hardware improvements in conjunction with improved diagnostics allowed the system to reach sustained operation at 400 kW beam power. Losses were at or near the 8 GeV injection energy where 95% beam transmission results in about 1.5 kW of beam loss. By minimizing and localizing loss, residual radiation levels fell while beam power was doubled. Lost beam was directed to either the collimation system or to the beam abort. Critical apertures were increased while improved instrumentation allowed optimal use of available apertures. We will summarize the impact of various loss control tools and the status and trends in residual radiation in the Main Injector.

  15. Meson Production in Proton-Proton and Antiproton - Interactions at Center of Mass Energy = 24.3 GEV

    Science.gov (United States)

    Singh, Vinay Mohan

    Experiment UA6 measured the inclusive production cross section of pi^0, eta, and omega mesons in the p_{T} range 3.5 to 6.1 GeV/c in the reactions;eqalignno {p + p&to M + Xcrnoalign{hbox {rm and}}|{p} + p& to M + Xcr}where M represents a meson and X any other associated particles, at center of mass energy sqrt{s} = 24.3 GeV. The experiment was located at the CERN SppS collider and utilized a fixed hydrogen gas jet as the target in oppositely circulating proton and antiproton beams of momenta 315 GeV/c. The apparatus could be rotated to select either proton-proton or antiproton-proton interactions. The meson production cross section results were obtained from the analysis of 3.7 inverse picobarns (pb ^{-1}) of pp data collected in 1988 and 3.2 pb^{-1} of pp data collected in 1989. The eta/pi ^0 production ratio is measured to be 0.61 +/- 0.03 +/- 0.07 for pp and 0.62 +/- 0.03 +/- 0.07 for pp. The omega/ pi^0 production ratio is measured to be 0.87 +/- 0.16 +/- 0.13 for pp and 0.84 +/- 0.16 +/- 0.13 for pp. The inclusive pi^0 cross section is determined as a function of p_{T} averaged over the rapidity range 0.6 <= y <= 1.2. Comparison of the production between pp and pp reveals no significant difference. The cross section and production ratios are also compared with results from other experiments and found to be in agreement.

  16. Stopping Frequency of Type III Solar Radio Bursts in Expanding Magnetic Flux Tubes

    CERN Document Server

    Reid, Hamish A S

    2015-01-01

    Understanding the properties of type III radio bursts in the solar corona and interplanetary space is one of the best ways to remotely deduce the characteristics of solar accelerated electron beams and the solar wind plasma. One feature of all type III bursts is the lowest frequency they reach (or stopping frequency). This feature reflects the distance from the Sun that an electron beam can drive the observable plasma emission mechanism. The stopping frequency has never been systematically studied before from a theoretical perspective. Using numerical kinetic simulations, we explore the different parameters that dictate how far an electron beam can travel before it stops inducing a significant level of Langmuir waves, responsible for plasma radio emission. We use the quasilinear approach to model self-consistently the resonant interaction between electrons and Langmuir waves in inhomogeneous plasma, and take into consideration the expansion of the guiding magnetic flux tube and the turbulent density of the in...

  17. Measurement of inclusive antiprotons from Au+Au collisions at square root of s(NN) = 130 GeV.

    Science.gov (United States)

    Adler, C; Ahammed, Z; Allgower, C; Amonett, J; Anderson, B D; Anderson, M; Averichev, G S; Balewski, J; Barannikova, O; Barnby, L S; Baudot, J; Bekele, S; Belaga, V V; Bellwied, R; Berger, J; Bichsel, H; Bland, L C; Blyth, C O; Bonner, B E; Boucham, A; Brandin, A; Cadman, R V; Caines, H; Calderón de la Barca Sánchez, M; Cardenas, A; Carroll, J; Castillo, J; Castro, M; Cebra, D; Chattopadhyay, S; Chen, M L; Chen, Y; Chernenko, S P; Cherney, M; Chikanian, A; Choi, B; Christie, W; Coffin, J P; Cormier, T M; Cramer, J G; Crawford, H J; DeMello, M; Deng, W S; Derevschikov, A A; Didenko, L; Draper, J E; Dunin, V B; Dunlop, J C; Eckardt, V; Efimov, L G; Emelianov, V; Engelage, J; Eppley, G; Erazmus, B; Fachini, P; Faine, V; Filimonov, K; Finch, E; Fisyak, Y; Flierl, D; Foley, K J; Fu, J; Gagliardi, C A; Gagunashvili, N; Gans, J; Gaudichet, L; Germain, M; Geurts, F; Ghazikhanian, V; Grabski, J; Grachov, O; Grigoriev, V; Guedon, M; Gushin, E; Hallman, T J; Hardtke, D; Harris, J W; Heffner, M; Heppelmann, S; Herston, T; Hippolyte, B; Hirsch, A; Hjort, E; Hoffmann, G W; Horsley, M; Huang, H Z; Humanic, T J; Hümmler, H; Igo, G; Ishihara, A; Ivanshin, Y I; Jacobs, P; Jacobs, W W; Janik, M; Johnson, I; Jones, P G; Judd, E; Kaneta, M; Kaplan, M; Keane, D; Kisiel, A; Klay, J; Klein, S R; Klyachko, A; Konstantinov, A S; Kotchenda, L; Kovalenko, A D; Kramer, M; Kravtsov, P; Krueger, K; Kuhn, C; Kulikov, A I; Kunde, G J; Kunz, C L; Kutuev, R K; Kuznetsov, A A; Lakehal-Ayat, L; Lamas-Valverde, J; Lamont, M A; Landgraf, J M; Lange, S; Lansdell, C P; Lasiuk, B; Laue, F; Lebedev, A; Lednický, R; Leontiev, V M; LeVine, M J; Li, Q; Lindenbaum, S J; Lisa, M A; Liu, F; Liu, L; Liu, Z; Liu, Q J; Ljubicic, T; Llope, W J; LoCurto, G; Long, H; Longacre, R S; Lopez-Noriega, M; Love, W A; Lynn, D; Majka, R; Margetis, S; Martin, L; Marx, J; Matis, H S; Matulenko, Y A; McShane, T S; Meissner, F; Melnick, Y; Meschanin, A; Messer, M; Miller, M L; Milosevich, Z; Minaev, N G; Mitchell, J; Moiseenko, V A; Moore, C F; Morozov, V; de Moura, M M; Munhoz, M G; Mutchler, G S; Nelson, J M; Nevski, P; Nikitin, V A; Nogach, L V; Norman, B; Nurushev, S B; Odyniec, G; Ogawa, A; Okorokov, V; Oldenburg, M; Olson, D; Paic, G; Pandey, S U; Panebratsev, Y; Panitkin, S Y; Pavlinov, A I; Pawlak, T; Perevoztchikov, V; Peryt, W; Petrov, V A; Platner, E; Pluta, J; Porile, N; Porter, J; Poskanzer, A M; Potrebenikova, E; Prindle, D; Pruneau, C; Radomski, S; Rai, G; Ravel, O; Ray, R L; Razin, S V; Reichhold, D; Reid, J G; Retiere, F; Ridiger, A; Ritter, H G; Roberts, J B; Rogachevski, O V; Romero, J L; Roy, C; Rykov, V; Sakrejda, I; Sandweiss, J; Saulys, A C; Savin, I; Schambach, J; Scharenberg, R P; Schmitz, N; Schroeder, L S; Schüttauf, A; Schweda, K; Seger, J; Seliverstov, D; Seyboth, P; Shahaliev, E; Shestermanov, K E; Shimanskii, S S; Shvetcov, V S; Skoro, G; Smirnov, N; Snellings, R; Sowinski, J; Spinka, H M; Srivastava, B; Stephenson, E J; Stock, R; Stolpovsky, A; Strikhanov, M; Stringfellow, B; Struck, C; Suaide, A A; Sugarbaker, E; Suire, C; Sumbera, M; Symons, T J; de Toledo, A S; Szarwas, P; Takahashi, J; Tang, A H; Thomas, J H; Thompson, M; Tikhomirov, V; Trainor, T A; Trentalange, S; Tribble, R E; Tokarev, M; Tonjes, M B; Trofimov, V; Tsai, O; Turner, K; Ullrich, T; Underwood, D G; Van Buren, G; VanderMolen, A M; Vanyashin, A; Vasilevski, I M; Vasiliev, A N; Vigdor, S E; Voloshin, S A; Wang, F; Ward, H; Watson, J W; Wells, R; Wenaus, T; Westfall, G D; Whitten, C; Wieman, H; Willson, R; Wissink, S W; Witt, R; Xu, N; Xu, Z; Yakutin, A E; Yamamoto, E; Yang, J; Yepes, P; Yurevich, V I; Zanevski, Y V; Zborovský, I; Zhang, H; Zhang, W M; Zoulkarneev, R; Zubarev, A N

    2001-12-24

    We report the first measurement of inclusive antiproton production at midrapidity in Au+Au collisions at square root of s(NN) = 130 GeV by the STAR experiment at RHIC. The antiproton transverse mass distributions in the measured transverse momentum range of 0.25antiproton rapidity density is found to scale approximately with the negative hadron multiplicity density.

  18. Which Srategy will stop Flu

    Directory of Open Access Journals (Sweden)

    O. V. Shamsheva

    2016-01-01

    Full Text Available Vaccine is essentially the only measure by which there is a real opportunity to eliminate an infectious disease. And the flu is no exception. The high variability of influenza virus A/H1N1, which causes a pandemic, and most epidemics, is the problem of creating effective etiotropic treatments and vaccines. The emergence of new vaccine manufacturing technologies, such as genetic engineering, DNA technology, allows for a fresh look at the problem of influenza eradication on the planet. Universal year-round mass vaccination against influenza, not just high-risk groups, should be included in all national vaccination program, but this strategy will help stop influenza infection.

  19. Maritime Adaptive Optics Beam Control

    Science.gov (United States)

    2010-09-01

    adaptive optics work at the NPS has been applied primarily to vibration control and segment alignment for flexible space telescopes and segmented mirror...a Fourier filter in the form of an iris or aperture stop is placed in the beam to select either the +1 or -1 diffractive order to propagate through...optical components on the table include lenses, mirrors, aperture stops, beamsplitters, and filters which reimage the system pupil plane and

  20. Design and Analysis of Muon Beam Stop Support Structures

    Energy Technology Data Exchange (ETDEWEB)

    Okafor, Udenna [Northern Illinois Univ., DeKalb, IL (United States)

    2015-01-01

    The primary objective of this thesis is to design and analyze support structures to be used in the installation, test and final positioning of the MBS throughout the life of the Mu2e experiment. There several requirements for the MBS imposed by both the scope of the experiment and, other components within the DS bore. The functions of the MBS are: 1. To limit the induced rates in the Tracker, the Calorimeter and the Cosmic Ray Veto due to backsplash-and-secondary interactions, and 2. To reduce radiation levels external to the Detector solenoid. The structures used in supporting the MBS will also adhere to requirements imposed by its functions. These requirements are critical to the support structures and affect design decisions. Other requirements critical to the design are imposed by the weight, positional tolerance and assembly procedure of the MBS, and also, the magnetic field and vacuum dose rate of the DS bore. A detailed breakdown of how each requirement affects the structural design can be found in chapter 2. Chapter 3 describes the design of each support structure and its attachment to the MBS while chapter 4 describes the results from structural analysis of the support structures. Chapter 5 describes evaluation for the design through testing and calculations while the conclusion in chapter 6 reports the current status at the time of this thesis submission with a plan for future work to be completed until final design and installation.

  1. Gauge mediation with light stops

    CERN Document Server

    Delgado, Antonio; Quiros, Mariano

    2015-01-01

    The mechanism of gauge mediated supersymmetry breaking (GMSB) solves the supersymmetric flavor problem although it requires superheavy stops to reproduce the experimental value (125 GeV) of the Higgs mass. A possible way out is to extend the MSSM Higgs sector with triplets which provide extra tree-level corrections to the Higgs mass. Triplets with neutral components getting vacuum expectation values (VEV) have the problem of generating a tree-level correction to the \\rho parameter. We introduce supersymmetric triplets with hypercharges Y=(0,\\pm 1), with a tree-level custodial SU(2)_L\\otimes SU(2)_R global symmetry in the Higgs sector protecting the \\rho parameter: a supersymmetric generalization of the Georgi-Machacek model. The renormalization group running from the messenger to the electroweak scale mildly breaks the custodial symmetry. We will present realistic low-scale scenarios, their main features being a Bino-like neutralino or right-handed stau as the NLSP, light (1 TeV) stops, exotic couplings (H^\\p...

  2. Monte Carlo simulations on the water-to-air stopping power ratio for carbon ion dosimetry.

    Science.gov (United States)

    Henkner, Katrin; Bassler, Niels; Sobolevsky, Nikolai; Jäkel, Oliver

    2009-04-01

    Many papers discussed the I value for water given by the ICRU, concluding that a value of about 80 +/- 2 eV instead of 67.2 eV would reproduce measured ion depth-dose curves. A change in the I value for water would have an effect on the stopping power and, hence, on the water-to-air stopping power ratio, which is important in clinical dosimetry of proton and ion beams. For energies ranging from 50 to 330 MeV/u and for one spread out Bragg peak, the authors compare the impact of the I value on the water-to-air stopping power ratio. The authors calculate ratios from different ICRU stopping power tables and ICRU reports. The stopping power ratio is calculated via track-length dose calculation with SHIELD-HIT07. In the calculations, the stopping power ratio is reduced to a value of 1.119 in the plateau region as compared to the cited value of 1.13 in IAEA TRS-398. At low energies the stopping power ratio increases by up to 6% in the last few tenths of a mm toward the Bragg peak. For a spread out Bragg peak of 13.5 mm width at 130 mm depth, the stopping power ratio increases by about 1% toward the distal end.

  3. CERN Summer Student Programme at the H-Beam, ASACUSA

    CERN Document Server

    Huzan, Myron

    2016-01-01

    The ASACUSA (Atomic Spectroscopy And Collisions Using Slow Antiprotons) collaboration opperates experiments at the Antiproton Decelerator (AD) at CERN. One of the goals is testing of CPT symmetry breaking by investigating the Ground State Hyperfine Splitting (GS-HFS) of antihydrogen (\\={H}), and comparing to that of hydrogen (H). The experiments are undertaken at the H-Beam and H-Bar experimental areas respectively and are both based on the Rabi-Spectroscopy method, but adapted for the respective experimental requirements. Being involved with the H-Beam experiment I will focus this report on the measurements undertaken on hydrogen, of which the aim is to measure the resonance frequencies of the Sigma ($\\sigma$$_{1}$) and Pi ($\\pi$$_{1}$) transitions within zero magnetic fields, an extension of the Ph.D. project of Martin Diermaier \\cite{MDiermaier}

  4. Impedances and beam stability issues of the Fermilab recycler ring

    Energy Technology Data Exchange (ETDEWEB)

    Ng, King-Yuen

    1996-04-01

    The Fermilab Recycler Ring (permanent magnets) will be built on top of the Fermilab Main Injector sharing the same tunnel; its main function is to recycle the anti-protons after a store in the Tevatron and to provide storage for them after after accumulation and cooling in the Accumulator. Estimates of coupling impedances show domination by space charge. Examination of longitudinal instabilities shows that microwave instability will not occur if there are only N = 2.53 x 10{sup 12} anti-protons in the beam. Longitudinal coupling-bunch instability during injection stacking does not appear possible because of long bunch lengths/short bunch gaps and lack of sharp resonances. Transverse instability, on the other hand, cannot be Landau damped by the momentum spread in the beam, but it can be cured by a small spread in the betatron tunes (either from space charge or an octupole).

  5. Calculation of stopping power ratios for carbon ion dosimetry.

    Science.gov (United States)

    Geithner, Oksana; Andreo, P; Sobolevsky, N; Hartmann, G; Jäkel, O

    2006-05-07

    Water-to-air stopping power ratio calculations for the ionization chamber dosimetry of clinical carbon ion beams with initial energies from 50 to 450 MeV/u have been performed using the Monte Carlo technique. To simulate the transport of a particle in water the computer code SHIELD-HIT v2 was used, which is a newly developed version where substantial modifications were implemented on its predecessor SHIELD-HIT v1 (Gudowska et al 2004 Phys. Med. Biol. 49 1933-58). The code was completely rewritten replacing formerly used single precision variables with double precision variables. The lowest particle transport specific energy was decreased from 1 MeV/u down to 10 keV/u by modifying the Bethe-Bloch formula, thus widening its range for medical dosimetry applications. In addition, the code includes optionally MSTAR and ICRU-73 stopping power data. The fragmentation model was verified and its parameters were also adjusted. The present code version shows excellent agreement with experimental data. It has been used to compute the physical quantities needed for the calculation of stopping power ratios, s(water,air), of carbon beams. Compared with the recommended constant value given in the IAEA Code of Practice, the differences found in the present investigations varied between 0.5% and 1% at the plateau region, respectively for 400 MeV/u and 50 MeV/u beams, and up to 2.3% in the vicinity of the Bragg peak for 50 MeV/u.

  6. Antiproton Flux in Cosmic Ray Propagation Models with Anisotropic Diffusion

    CERN Document Server

    Grajek, Phillip

    2010-01-01

    Recently a cosmic ray propagation model has been introduced, where anisotropic diffusion is used as a mechanism to allow for $\\mathcal{O}(100)$ km/s galactic winds. This model predicts a reduced antiproton background flux, suggesting an excess is being observed. We implement this model in GALPROP v50.1 and perform a $\\chi^2$ analysis for B/C, $^{10}$Be/$^{9}$Be, and the recent PAMELA $\\bar{p}/p$ datasets. By introducing a power-index parameter $\\alpha$ that dictates the dependence of the diffusion coefficient $D_{xx}$ on height $|z|$ away from the galactic plane, we confirm that isotropic diffusion models with $\\alpha=0$ cannot accommodate high velocity convective winds suggested by ROSAT, while models with $\\alpha=1$ ($D_{xx}\\propto |z|$) can give a very good fit. A fit to B/C and $^{10}$Be/$^{9}$Be data predicts a lower $\\bar{p}/p$ flux ratio than the PAMELA measurement at energies between approximately 2 GeV to 20 GeV. A combined fit including in addition the $\\bar{p}/p$ data is marginal, suggesting only a...

  7. Constraining pre big-bang-nucleosynthesis expansion using cosmic antiprotons

    Energy Technology Data Exchange (ETDEWEB)

    Schelke, M. [Istituto Nazionale di Fisica Nucleare, Torino (Italy); Catena, R. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Fornengo, N. [Torino Univ. (Italy). Dipt. di Fisica Teorica]|[Istituto Nazionale di Fisica Nucleare, Torino (Italy); Masiero, A. [Pavoa Univ. (Italy). Dipt. di Fisica]|[Istituto Nazionale di Fisica Nucleare, Padova (Italy); Pietroni, M. [Istituto Nazionale di Fisica Nucleare, Padova (Italy)

    2006-06-15

    A host of dark energy models and non-standard cosmologies predict an enhanced Hubble rate in the early Universe: perfectly viable models, which satisfy Big Bang Nucleosynthesis (BBN), cosmic microwave background and general relativity tests, may nevertheless lead to enhancements of the Hubble rate up to many orders of magnitude. In this paper we show that strong bounds on the pre-BBN evolution of the Universe may be derived, under the assumption that dark matter is a thermal relic, by combining the dark matter relic density bound with constraints coming from the production of cosmic-ray antiprotons by dark matter annihilation in the Galaxy. The limits we derive can be sizable and apply to the Hubble rate around the temperature of dark matter decoupling. For dark matter masses lighter than 100 GeV, the bound on the Hubble-rate enhancement ranges from a factor of a few to a factor of 30, depending on the actual cosmological model, while for a mass of 500 GeV the bound falls in the range 50-500. Uncertainties in the derivation of the bounds and situations where the bounds become looser are discussed. We finally discuss how these limits apply to some specific realizations of non-standard cosmologies: a scalar-tensor gravity model, kination models and a Randall-Sundrum D-brane model. (Orig.)

  8. Density functional theory investigation of antiproton-helium collisions

    CERN Document Server

    Henkel, N; Lüdde, H J; Kirchner, T; 10.1103/PhysRevA.80.032704

    2011-01-01

    We revisit recent developments in the theoretical foundations of time-dependent density functional theory (TDDFT). TDDFT is then applied to the calculation of total cross sections for ionization processes in the antiproton-Helium collision system. The Kohn-Sham potential is approximated as the sum of the Hartree-exchange potential and a correlation potential that was proposed in the context of laser-induced ionization. Furthermore, some approaches to the problem of calculating the ionization probabilities from the density are discussed. Small projectile energies below 5keV are considered as well as those in the range from 5 to 1000 keV. Results are compared with former calculations and with experimental data. We find that the correlation potential yields no obvious improvement of the results over the exchange-only approximation where the correlation potential is neglected. Furthermore, we find the problem of calculating the desired observables crucial, introducing errors of at least the same order of magnitud...

  9. Effects of beam velocity and density on an ion-beam pulse moving in magnetized plasmas

    CERN Document Server

    Zhao, Xiao-ying; Zhao, Yong-tao; Qi, Xin; Yang, Lei

    2016-01-01

    The wakefield and stopping power of an ion-beam pulse moving in magnetized plasmas are investigated by particle-in-cell (PIC) simulations. The effects of beam velocity and density on the wake and stopping power are discussed. In the presence of magnetic field, it is found that beside the longitudinal conversed V-shaped wakes, the strong whistler wave are observed when low-density and low-velocity pulses moving in plasmas. The corresponding stopping powers are enhanced due to the drag of these whistler waves. As beam velocities increase, the whistler waves disappear, and only are conversed V-shape wakes observed. The corresponding stopping powers are reduced compared with these in isotropic plasmas. When high-density pulses transport in the magnetized plasmas, the whistler waves are greatly inhibited for low-velocity pulses and disappear for high-velocity pulses. Additionally, the magnetic field reduces the stopping powers for all high-density cases.

  10. Multiple ionization of He, Ne, and Ar by fast protons and antiprotons

    Energy Technology Data Exchange (ETDEWEB)

    Andersen, L.H.; Hvelplund, P.; Knudsen, H.; Moller, S.P.; Sorensen, A.H.; Elsener, K.; Rensfelt, K.; Uggerhoj, E.

    1987-10-15

    Single and multiple ionization of He, Ne, and Ar has been studied experimentally by impact of fast protons and antiprotons. The single-ionization cross sections obtained with protons and antiprotons are found to be the same. The double-ionization cross sections obtained with antiprotons, however, are much larger than those obtained with protons at equal velocity. This difference is found for all three gases but the effect is largest for He and Ne, where the difference is about a factor of 2 at 1 MeV/amu. The difference is discussed in terms of interference between two collision mechanisms which both result in double-electron escape. Experimental information on the magnitude of the interference term is obtained by inclusion of double-ionization data, partly obtained in this work, for fast electron and ..cap alpha..-particle impact. For triple ionization of Ne, we also find that antiprotons yield much larger cross sections than protons do. Identical cross sections, however, are found for triple ionization of Ar with protons and antiprotons. This is believed to be due to the fact that triple ionization of Ar is mainly a consequence of a single vacancy produced in an inner shell followed by electronic rearrangement. This observation supports the interpretation that the observed charge effect is due to an interference effect in the outermost shell.

  11. Evidence for the Stochastic Acceleration of Secondary Antiprotons by Supernova Remnants

    Energy Technology Data Exchange (ETDEWEB)

    Cholis, Ilias [Johns Hopkins U.; Hooper, Dan [Chicago U., KICP; Linden, Tim [Ohio State U.

    2017-01-16

    The antiproton-to-proton ratio in the cosmic-ray spectrum is a sensitive probe of new physics. Using recent measurements of the cosmic-ray antiproton and proton fluxes in the energy range of 1-1000 GeV, we study the contribution to the $\\bar{p}/p$ ratio from secondary antiprotons that are produced and subsequently accelerated within individual supernova remnants. We consider several well-motivated models for cosmic-ray propagation in the interstellar medium and marginalize our results over the uncertainties related to the antiproton production cross section and the time-, charge-, and energy-dependent effects of solar modulation. We find that the increase in the $\\bar{p}/p$ ratio observed at rigidities above $\\sim$ 100 GV cannot be accounted for within the context of conventional cosmic-ray propagation models, but is consistent with scenarios in which cosmic-ray antiprotons are produced and subsequently accelerated by shocks within a given supernova remnant. In light of this, the acceleration of secondary cosmic rays in supernova remnants is predicted to substantially contribute to the cosmic-ray positron spectrum, accounting for a significant fraction of the observed positron excess.

  12. Modeling of the Near-Earth Low-Energy Antiproton Fluxes

    Directory of Open Access Journals (Sweden)

    U. B. Jayanthi

    2011-01-01

    Full Text Available The local interstellar antiproton spectrum is simulated taking into account antineutron decay, (He,p interaction, secondary and tertiary antiproton production, and the solar modulation in the “force field” approximation. Inclusive invariant cross-sections were obtained through a Monte Carlo procedure using the Multistage Dynamical Model code simulating various processes of the particle production. The results of the simulations provided flux values of 4⋅10−3 to 10−2 and 10−2 to 1.7⋅10−2 antiprotons/(2 s sr GeV at energies of 0.2 and 1 GeV, respectively, for the solar maximum and minimum epochs. Simulated flux of the trapped antiprotons in the inner magnetosphere due to galactic cosmic ray (GCR interactions with the atmospheric constituents exceeds the galactic antiproton flux up to several orders. These simulation results considering the assumptions with the attendant limitations are in comprehensive agreement with the experimental data including the PAMELA ones.

  13. New calculation of antiproton production by cosmic ray protons and nuclei

    CERN Document Server

    Kachelriess, Michael; Ostapchenko, Sergey S

    2015-01-01

    A dramatic increase in the accuracy and statistics of space-borne cosmic ray (CR) measurements has yielded several breakthroughs over the last several years. The most puzzling is the rise in the positron fraction above ~10 GeV over the predictions of the propagation models assuming pure secondary production. The accuracy of the antiproton production cross section is critical for astrophysical applications and searches for new physics since antiprotons in CRs seem to hold the keys to many puzzles including the origin of those excess positrons. However, model calculations of antiproton production in CR interactions with interstellar gas are often employing parameterizations that are out of date or are using outdated physical concepts. That may lead to an incorrect interpretation of antiproton data which could have broad consequences for other areas of astrophysics. In this work, we calculate antiproton production in pp-, pA-, and AA-interactions using EPOS-LHC and QGSJET-II-04, two of the most advanced Monte Ca...

  14. Direct detection of antiprotons with the Timepix3 in a new electrostatic selection beamline

    Science.gov (United States)

    Pacifico, N.; Aghion, S.; Alozy, J.; Amsler, C.; Ariga, A.; Ariga, T.; Bonomi, G.; Bräunig, P.; Bremer, J.; Brusa, R. S.; Cabaret, L.; Caccia, M.; Campbell, M.; Caravita, R.; Castelli, F.; Cerchiari, G.; Chlouba, K.; Cialdi, S.; Comparat, D.; Consolati, G.; Demetrio, A.; Di Noto, L.; Doser, M.; Dudarev, A.; Ereditato, A.; Evans, C.; Ferragut, R.; Fesel, J.; Fontana, A.; Gerber, S.; Giammarchi, M.; Gligorova, A.; Guatieri, F.; Haider, S.; Holmestad, H.; Huse, T.; Jordan, E.; Kellerbauer, A.; Kimura, M.; Krasnický, D.; Lagomarsino, V.; Lansonneur, P.; Lawler, G.; Lebrun, P.; Llopart, X.; Malbrunot, C.; Mariazzi, S.; Marx, L.; Matveev, V.; Mazzotta, Z.; Nebbia, G.; Nedelec, P.; Oberthaler, M.; Pagano, D.; Penasa, L.; Petracek, V.; Pistillo, C.; Prelz, F.; Prevedelli, M.; Ravelli, L.; Resch, L.; Røhne, O. M.; Rotondi, A.; Sacerdoti, M.; Sandaker, H.; Santoro, R.; Scampoli, P.; Smestad, L.; Sorrentino, F.; Spacek, M.; Storey, J.; Strojek, I. M.; Testera, G.; Tietje, I.; Tlustos, L.; Widmann, E.; Yzombard, P.; Zavatarelli, S.; Zmeskal, J.; Zurlo, N.

    2016-09-01

    We present here the first results obtained employing the Timepix3 for the detection and tagging of annihilations of low energy antiprotons. The Timepix3 is a recently developed hybrid pixel detector with advanced Time-of-Arrival and Time-over-Threshold capabilities and has the potential of allowing precise kinetic energy measurements of low energy charged particles from their time of flight. The tagging of the characteristic antiproton annihilation signature, already studied by our group, is enabled by the high spatial and energy resolution of this detector. In this study we have used a new, dedicated, energy selection beamline (GRACE). The line is symbiotic to the AEgIS experiment at the CERN Antiproton Decelerator and is dedicated to detector tests and possibly antiproton physics experiments. We show how the high resolution of the Timepix3 on the Time-of-Arrival and Time-over-Threshold information allows for a precise 3D reconstruction of the annihilation prongs. The presented results point at the potential use of the Timepix3 in antimatter-research experiments where a precise and unambiguous tagging of antiproton annihilations is required.

  15. Direct detection of antiprotons with the Timepix3 in a new electrostatic selection beamline

    Energy Technology Data Exchange (ETDEWEB)

    Pacifico, N., E-mail: nicola.pacifico@cern.ch [Institute of Physics and Technology, University of Bergen, Allgaten 55, 5007 Bergen (Norway); Aghion, S. [Politecnico of Milano, Piazza Leonardo da Vinci 32, 20133 Milano (Italy); INFN Milano, via Celoria 16, 20133 Milano (Italy); Alozy, J. [Physics Department, CERN, 1211 Geneva 23 (Switzerland); Amsler, C.; Ariga, A.; Ariga, T. [Laboratory for High Energy Physics, Albert Einstein Center for Fundamental Physics, University of Bern, 3012 Bern (Switzerland); Bonomi, G. [Department of Mechanical and Industrial Engineering, University of Brescia, via Branze 38, 25123 Brescia (Italy); INFN Pavia, via Bassi 6, 27100 Pavia (Italy); Bräunig, P. [Kirchhoff-Institute for Physics, Heidelberg University, Im Neuenheimer Feld 227, 69120 Heidelberg (Germany); Bremer, J. [Physics Department, CERN, 1211 Geneva 23 (Switzerland); Brusa, R.S. [Department of Physics, University of Trento, via Sommarive 14, 38123 Povo, Trento (Italy); TIFPA/INFN Trento, via Sommarive 14, 38123 Povo, Trento (Italy); Cabaret, L. [Laboratory Aimé Cotton, University of Paris-Sud, ENS Cachan, CNRS, University Paris-Saclay, 91405 Orsay Cedex (France); Caccia, M. [INFN Milano, via Celoria 16, 20133 Milano (Italy); Department of Science, University of Insubria, Via Valleggio 11, 22100 Como (Italy); Campbell, M. [Physics Department, CERN, 1211 Geneva 23 (Switzerland); Caravita, R. [Department of Physics, University of Genova, via Dodecaneso 33, 16146 Genova (Italy); INFN Genova, via Dodecaneso 33, 16146 Genova (Italy); Castelli, F. [INFN Milano, via Celoria 16, 20133 Milano (Italy); Department of Physics, University of Milano, via Celoria 16, 20133 Milano (Italy); Cerchiari, G. [Max Planck Institute for Nuclear Physics, Saupfercheckweg 1, 69117 Heidelberg (Germany); Chlouba, K. [Czech Technical University, Prague, Brehov 7, 11519 Prague 1 (Czech Republic); and others

    2016-09-21

    We present here the first results obtained employing the Timepix3 for the detection and tagging of annihilations of low energy antiprotons. The Timepix3 is a recently developed hybrid pixel detector with advanced Time-of-Arrival and Time-over-Threshold capabilities and has the potential of allowing precise kinetic energy measurements of low energy charged particles from their time of flight. The tagging of the characteristic antiproton annihilation signature, already studied by our group, is enabled by the high spatial and energy resolution of this detector. In this study we have used a new, dedicated, energy selection beamline (GRACE). The line is symbiotic to the AEgIS experiment at the CERN Antiproton Decelerator and is dedicated to detector tests and possibly antiproton physics experiments. We show how the high resolution of the Timepix3 on the Time-of-Arrival and Time-over-Threshold information allows for a precise 3D reconstruction of the annihilation prongs. The presented results point at the potential use of the Timepix3 in antimatter-research experiments where a precise and unambiguous tagging of antiproton annihilations is required.

  16. Study of Interaction of Low-Energy Antiprotons with H$^{2}$,He$^{3}$,He$^{4}$,Ne-Nuclei Using a Streamer Chamber in Magnetic Field

    CERN Multimedia

    2002-01-01

    The aim of this experiment is the systematic study of the interaction between low-energy antiprotons and the H|2,~He|3,~He|4,~Ne-nuclei using a self shunted streamer chamber in a magnetic field exposed to the antiproton beam of the LEAR facility. The properties of the self shunted streamer chamber, which allows the use of the filling gas (hydrogen, helium, neon at a pressure of l~atm) as a target, permit to carry out experiments also in the very low-energy region. \\\\ \\\\ The experimental apparatus is suitable for a large programme of measurements. We plan to measure the @*H|2 cross section and the spectator momentum distributions at @* momenta lower than 250~MeV/c, where data are lacking. It is interesting to study for the first time the @*He|3 and @*He|4 interactions measuring the cross sections and the emitted particle distributions. Among other things the knowledge of the branching ratio of the @*He|4 annihilation channels clarifies some open cosmological questions. The study of the process of nuclear absor...

  17. Light stop squarks and b-tagging

    CERN Document Server

    Ferretti, Gabriele; Petersson, Christoffer; Torre, Riccardo

    2015-01-01

    A significant part of the parameter space for light stop squarks still remains unconstrained by collider searches. For both R-Parity Conserving (RPC) and R-Parity Violating (RPV) scenarios there are regions in which the stop mass is around or below the top quark mass that are particularly challenging experimentally. Here we review the status of light stop searches, both in RPC and RPV scenarios. We also propose strategies, generally based on exploiting b-tagging, to cover the unconstrained regions.

  18. Antiproton–to–electron mass ratio determined by two-photon laser spectroscopy of antiprotonic helium atoms

    Directory of Open Access Journals (Sweden)

    Sótér A.

    2014-03-01

    Full Text Available The ASACUSA collaboration of CERN has recently carried out two-photon laser spectroscopy of antiprotonic helium atoms. Three transition frequencies were determined with fractional precisions of 2.3–5 parts in 109. By comparing the results with three-body QED calculations, the antiproton-to-electron mass ratio was determined as 1836.1526736(23.

  19. First Beam Splash Events 2008

    CERN Multimedia

    Collaboration, CMS

    2008-01-01

    10th September 2008 at 10.00 a.m. CMS saw the beam pass through the experiment for the first time ever, in the clockwise direction. The beam was initially intentionally stopped by blocks around 154 metres before CMS at Point 5, producing these images of the debris or "splash" from the particles hitting the blocks. After removal of the blocks, the beam then passed through CMS successfully. At 14.30 beam then passed successfully in the anticlockwise direction through the experiment.

  20. Antiproton production and antideuteron production limits in relativistic heavy ion collisions

    Energy Technology Data Exchange (ETDEWEB)

    Dover, C.B. [Brookhaven National Laboratory, Upton, New York 11973 (United States); Huang, H.Z.; Van Buren, G. [University of California at Los Angeles, Los Angeles, California 90095 (United States); Barish, K.N. [University of California at Riverside, Riverside, California 92521 (United States); Fadem, B.; Hill, J.C.; Hoversten, R.; Lajoie, J.G.; Libby, B.; Wohn, F.K. [Iowa State University, Ames, Iowa 50011 (United States); Rabin, M.S. [University of Massachusetts, Amherst, Massachusetts 01003 (United States); Haridas, P.; Pless, I.A. [Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Armstrong, T.A.; Smith, G.A.; Toothacker, W.S. [Pennsylvania State University, University Park, Pennsylvania 16802 (United States); Davies, R.; Hirsch, A.S.; Porile, N.T.; Rimai, A.; Scharenberg, R.P.; Tincknell, M.L. [Purdue University, West Lafayette, Indiana 47907 (United States); Lainis, T. [United States Military Academy, West Point, New York 10996 (United States); Greene, S.V.; Miller, T.E.; Reid, J.D.; Rose, A. [Vanderbilt University, Nashville, Tennessee 37235 (United States); Bennett, S.J.; Cormier, T.M.; Fachini, P.; Li, Q.; Munhoz, M.G.; Pruneau, C.A. [Wayne State University, Detroit, Michigan 48201 (United States); Batsoulli, S.; Chikanian, A.; Coe, S.D.; Finch, L.E.; George, N.K.; Kumar, B.S.; Majka, R.D.; Nagle, J.L.; Pope, J.K.; Rotondo, F.S.; Sandweiss, J.; Slaughter, A.J.; Xu, Z. [Yale University, New Haven, Connecticut 06520 (United States)

    1999-05-01

    We present results from Experiment 864 for antiproton production and antideuteron limits in Au + Pb collisions at 11.5 GeV/c per nucleon. We have measured invariant multiplicities for antiprotons for rapidities 1.4{lt}y{lt}2.4 at low transverse momentum as a function of collision geometry. When compared with the results from Experiment 878 our measurements suggest a significant contribution to the measured antiproton yield from the decay of strange antibaryons. We have also searched for antideuterons and see no statistically significant signal. Thus, we set upper limits on the production at approximately 3{times}10{sup {minus}7} per 10{percent} highest multiplicity Au+Pb interaction. {copyright} {ital 1999} {ital The American Physical Society}

  1. Measurements of Electron Spectra in the Forward Direction in Slow-Antiproton Carbon-Foil Collisions

    Science.gov (United States)

    Yamazaki, Yasunori; Kuroki, Kenro; Komaki, Ken-Ichiro; Andersen, Lars H.; Horsdal-Pedersen, Erik; Hvelplund, Preben; Knudsen, Helge; M{ø}ller, S{ø}ren P.; Uggerh{ø}j, Erik; Elsener, Konrad

    1990-08-01

    The spectrta of electrons emitted in the forward direction from antiproton and proton bombardments on carbon foils have been studied for projectile energies from 500 to 750 keV. Our main observation is that at the electron energy where the well-known convoy peak is observed for proton impact, the spectrum for equivelocity antiprotons is smooth, showing no indication of a deep anticusp. However, around 50 eV below the electron energy where the cusp is observed for proton impact, we have observed a small peak for antiproton impact. The energy and the relative intensity of the bump are found to be consistent with those predicted for electrons released from a wake-riding state.

  2. A fussy revisitation of antiprotons as a tool for Dark Matter searches

    CERN Document Server

    Boudaud, Mathieu

    2015-01-01

    Antiprotons are regarded as a powerful probe for Dark Matter (DM) indirect detection and indeed current data from \\PAMELA\\ have been shown to lead to stringent constraints. However, in order to exploit their constraining/discovery power properly, great attention must be put into effects (linked to their propagation in the Galaxy) which may be perceived as subleading but actually prove to be quite relevant. We revisit the computation of the astrophysical background and of the DM antiproton fluxes fully including the effects of: diffusive reacceleration, energy losses including tertiary component and solar modulation (in a force field approximation). Using the updated proton and helium fluxes just released by the \\AMS\\ experiment we reevaluate the secondary astrophysical antiproton to proton ratio and its uncertainties, and compare it with the ratio preliminarly reported by \\AMS. We find no unambiguous evidence for a significant excess with respect to expectations. Yet, some preference for a flatter energy depe...

  3. Classification of high-energy antiprotons on electrons background based on calorimeter data in PAMELA experiment

    Science.gov (United States)

    Dunaeva, O. A.; Alekseev, V. V.; Bogomolov, Yu V.; Lukyanov, A. D.; Malakhov, V. V.; Mayorov, A. G.; Rodenko, S. A.

    2017-01-01

    In modern experimental physics a heterogeneous coordinate-sensitive calorimeters are widely used due to their good characteristics and possibilities to obtain a three-dimensional information of particles interactions. Especially it is important at high-energies when electromagnetic or hadron showers are arise. We propose a quit efficient method to identify antiprotons (positrons) with energies more than 10 GeV on electron (proton) background by calorimeter of such kind. We construct the AdaBoost classifier and SVM to separate particles into two classes, different combinations of energy release along reconstructed particle trajectory were used as feature vector. We test a preliminary version of the method on a calorimeter of the PAMELA magnetic spectrometer. For high-energy particles we got a good quality of classification: it lost about 5 · 10‑2 of antiprotons, and less than 4 · 10‑4 of electrons were classified to antiproton class.

  4. Antiproton signatures from astrophysical and dark matter sources at the galactic center

    CERN Document Server

    Cembranos, J A R; Maroto, A L

    2015-01-01

    The center of our Galaxy is a complex region characterized by extreme phenomena. The presence of the supermassive Sagittarius A* black hole, a high Dark Matter density and an even higher baryonic density are able to produce very energetic processes. Indeed, high energetic gamma rays have been observed by different telescopes, although its origin is not clear. In this work, we constrain the possible antiproton flux component associated to this signal. The expected secondary astrophysical antiproton background already saturates the observed data. It implies that any other important astrophysical source leads to an inconsistent excess, since the theoretical uncertainties corresponding to the mentioned background are small. The constraints depend on the diffusion model and the spectral features of the source. In particular, we consider antiproton spectra described by a power-law, a monochromatic signal and a Standard Model particle-antiparticle channel production.

  5. Collisions of low-energy antiprotons and protons with atoms and molecules

    Energy Technology Data Exchange (ETDEWEB)

    Luehr, Armin

    2010-02-18

    Antiproton (anti p) collisions have evolved to a powerful tool for the testing of dynamic electron correlations in atoms and molecules. While advances in the understanding of anti p collisions with the simplest one- and two-electron atoms, H and He, have been achieved experiment and theory did not agree for low-energy anti p+He collisions (<40 keV), stimulating a vivid theoretical activity. On the other hand, only very few theoretical anti p studies can be found considering molecular as well as other atomic targets, in contrast to proton (p) collisions. This is in particular true for anti p impacts on H{sub 2} despite its fundamental role in representing the simplest two-electron molecule. The obtained results may be useful for the anti p experiments at CERN (e.g., antihydrogen production) and in particular for the facility design of low-energy anti p storage rings (e.g., at FLAIR) where a precise knowledge of the anti p interaction with the dominant residual-gas molecule H{sub 2} is needed. In this work a nonperturbative, time-dependent numerical approach is developed which describes ionization and excitation of atoms or molecules by either anti p or p impact based on the impact-parameter method. A spectral close-coupling method is employed for solving the time-dependent Schroedinger equation in which the scattering wave function is expanded in (effective) one- or two-electron eigenstates of the target. This includes for the first time a full two-electron, two-center description of the H{sub 2} molecule in anti p collisions. The radial part of the one-electron eigenstates is expanded in B splines while the two-electron basis is obtained with a configurationinteraction approach. Calculations are performed for anti p collisions with H, H{sub 2}{sup +}, and H{sub 2} as well as with He and alkali-metal atoms Li, Na, K, and Rb. Additionally, data are obtained for p collisions with H{sub 2}, Li, Na, and K. The developed method is tested and validated by detailed

  6. Nuclear stopping and rapidity loss in Au+Au collisions at sqrt{s_{NN}}=62.4 GeV

    CERN Document Server

    Arsene, I C

    2009-01-01

    Transverse momentum spectra of protons and anti-protons measured in the rapidity range 0anti-protons and net-protons N()p-N(pbar) have been deduced from the spectra over a rapidity range wide enough to observe the expected maximum net-baryon density. From mid-rapidity to y=1 the net-proton yield is roughly constant (dN/dy ~ 10),but rises to dN/dy ~25 at 2.3beam rapidity. The measured rapidity distributions are compared to model predictions. Systematics of net-baryon distributions and rapidity loss vs. collision energy are discussed.

  7. Stopping power of C, O and Cl in tantalum oxide

    Energy Technology Data Exchange (ETDEWEB)

    Barradas, Nuno P., E-mail: nunoni@ctn.ist.utl.pt [Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, Estrada Nacional 10, ao km 139.7, 2695-066 Bobadela LRS (Portugal); Laboratório de Engenharia Nuclear, Instituto Superior Técnico, Universidade de Lisboa, Estrada Nacional 10, ao km 139.7, 2695-066 Bobadela LRS (Portugal); Alves, E. [Associação Euratom/IST, Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade Técnica de Lisboa, Av. Rovisco Pais, Lisboa 1049-001 (Portugal); Fonseca, M. [Dep. Física, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829- 516 Caparica (Portugal); ISLA Campus Lisboa| Laureate International Universities, 1500-210 Lisboa (Portugal); Siketić, Z.; Bogdanović Radović, I. [Ruđer Bošković Institute, P.O. Box 180, 10002 Zagreb (Croatia)

    2014-08-01

    Highlights: •We measured the stopping power of C, O, and Cl in tantalum oxide. •A bulk sample method was used, with Bayesian inference data analysis. •Good agreement was found with SRIM2012 calculations. -- Abstract: Tantalum oxide is used in a variety of applications due to its high bandgap, high-K and high index of refraction. Unintentional impurities can change properties of tantalum oxide, and heavy ion elastic recoil detection is a method that can play a fundamental role in the quantification of those impurities. Furthermore, tantalum oxide is frequently part of the samples that also include other materials, which are often analysed with ion beam techniques. However, there are very few reported stopping power measurements for tantalum oxide, and data analysis relies not only on interpolation from a sparse data base but also on the Bragg rule. As is well known, the Bragg rule is often inaccurate for oxides, particularly when the difference in atomic numbers of the involved elements is very large as is case for Ta{sub 2}O{sub 5}. We have used a bulk method, previously developed by us and applied successfully to other systems, to determine experimentally the stopping power of tantalum oxide for three different ion types: C, O and Cl. In the present paper the results of our measurements and bulk method analysis are presented.

  8. Monte Carlo Simulations on the water-to-air stopping power ratio for carbon ion dosimetry

    DEFF Research Database (Denmark)

    Henkner, Katrin; Bassler, Niels; Sobolevsky, Nikolai;

    2009-01-01

    Many papers discussed the I value for water given by the ICRU, concluding that a value of about 80±2  eV instead of 67.2  eV would reproduce measured ion depth-dose curves. A change in the I value for water would have an effect on the stopping power and, hence, on the water-to-air stopping power...... ratio, which is important in clinical dosimetry of proton and ion beams. For energies ranging from 50  to  330  MeV/u and for one spread out Bragg peak, the authors compare the impact of the I value on the water-to-air stopping power ratio. The authors calculate ratios from different ICRU stopping power...... tables and ICRU reports. The stopping power ratio is calculated via track-length dose calculation with SHIELD-HIT07. In the calculations, the stopping power ratio is reduced to a value of 1.119 in the plateau region as compared to the cited value of 1.13 in IAEA TRS-398. At low energies the stopping...

  9. An ultra low-noise AC beam transformer and digital signal processing system for CERN's ELENA ring

    CERN Document Server

    Angoletta, M E; Caspers, F; Federmann, S; Molendijk, J; Pedersen, F; Sanchez-Quesada, J

    2013-01-01

    CERN’s Extra Low ENergy Antiproton (ELENA) ring is a new synchrotron that will be commissioned in 2016 to further decelerate the antiprotons coming from CERN’s Antiproton Decelerator (AD). Essential longitudinal diagnostics required for commissioning and operation include the intensity measurement for bunched and debunched beams and the measurement of p/p for debunched beams to assess the electron cooling performance. The beam phase information is also needed by the Low-Level RF (LLRF) system. The baseline system for providing the required beam parameters and signals is based upon two ultra-low-noise AC beam transformers and associated digital signal processing. The AC beam transformers cover different frequency regions and are an adaptation to the ELENA layout of those used in the AD. Two AC beam transformers will also be installed in the extraction lines to provide beam intensity measurements. The digital signal processing will be carried out with the leadingedge hardware family used for ELENA’s L...

  10. One of the most striking pictures of a vacuum chamber where the proton beams collide in the ISR

    CERN Multimedia

    CERN PhotoLab

    1973-01-01

    The Intersecting Storage Rings (ISR), the world’s first proton-proton collider, started up in 1971, and later provided the first proton-antiproton collisions and the first collisions of beams of heavier ions (alpha particles).

  11. First measurement of the antiproton-nucleus annihilation cross section at 125 keV

    Energy Technology Data Exchange (ETDEWEB)

    Aghai-Khozani, H. [Max-Planck-Institut fur Quantenoptik (Germany); Barna, D. [CERN (Switzerland); Corradini, M. [Università degli Studi di Brescia, Dipartimento di Ingegneria dell’Informazione (Italy); Salvador, D. De [Università di Padova, Dipartimento di Fisica e Astronomia (Italy); Hayano, R. [University of Tokyo, Department of Physics (Japan); Hori, M. [Max-Planck-Institut fur Quantenoptik (Germany); Kobayashi, T. [University of Tokyo, Department of Physics (Japan); Leali, M.; Lodi-Rizzini, E.; Mascagna, V. [Università degli Studi di Brescia, Dipartimento di Ingegneria dell’Informazione (Italy); Prest, M. [Università degli Studi dell’Insubria, Dipartimento di Scienza e Alta Tecnologia (Italy); Seiler, D. [TUM Department of Physics E12 (Germany); Soter, A. [Max-Planck-Institut fur Quantenoptik (Germany); Todoroki, K. [University of Tokyo, Department of Physics (Japan); Vallazza, E. [Istituto Nazionale di Fisica Nucleare, Sezione di Trieste (Italy); Venturelli, L., E-mail: venturelli@bs.infn.it [Università degli Studi di Brescia, Dipartimento di Ingegneria dell’Informazione (Italy)

    2015-08-15

    The first observation of in-flight antiproton-nucleus annihilation at ∼130 keV obtained with the ASACUSA detector has demonstrated that the measurement of the cross section of the process is feasible at such extremely low energies Aghai-Khozani, H., et al., Eur. Phys. J. Plus 127, 55 (2012). Here we present the results of the data analysis with the evaluations of the antiproton annihilation cross sections on carbon, palladium and platinum targets at ∼125 keV.

  12. Centrifugal separation and equilibration dynamics in an electron-antiproton plasma

    CERN Document Server

    Andresen, G B; Baquero-Ruiz, Marcelo; Bertsche, William; Bowe, Paul D; Butler, Eoin; Cesar, Claudio L; Chapman, Steven; Charlton, Michael; Deller, A; Eriksson, S; Fajans, Joel; Friesen, Tim; Fujiwara, Makoto C; Gill, David R; Gutierrez, A; Hangst, Jeffrey S; Hardy, Walter N; Hayden, Michael E; Humphries, Andrew J; Hydomako, Richard; Jonsell, Svante; Madsen, Niels; Menary, Scott; Nolan, Paul; Olin, Art; Povilus, Alexander; Pusa, Petteri; Robicheaux, Francis; Sarid, Eli; Silveira, Daniel M; So, Chukman; Storey, James W; Thompson, Robert I; van der Werf, Dirk P; Wurtele, Jonathan S; Yamazaki, Yasunori

    2011-01-01

    Charges in cold, multiple-species, non-neutral plasmas separate radially by mass, forming centrifugally-separated states. Here, we report the first detailed measurements of such states in an electron-antiproton plasma, and the first observations of the separation dynamics in any centrifugally-separated system. While the observed equilibrium states are expected and in agreement with theory, the equilibration time is approximately constant over a wide range of parameters, a surprising and as yet unexplained result. Electron-antiproton plasmas play a crucial role in antihydrogen trapping experiments.

  13. Antiproton and proton collisions with the alkali-metal atoms Li, Na, and K

    DEFF Research Database (Denmark)

    Lühr, Armin Christian; Saenz, Alejandro

    2008-01-01

    Single-electron ionization and excitation cross sections as well as cross sections for excitation into the first excited p state of the alkali-metal atoms Li(2s), Na(3s), and K(4s) colliding with antiprotons and protons were calculated using a time-dependent channel-coupling approach....... For antiprotons an impact-energy range from 0.25 to 1000 keV and for protons from 2 to 1000 keV was considered. The target atoms are treated as effective one-electron systems using a model potential. The results are compared with theoretical and experimental data from literature and calculated cross sections...

  14. Baryon fraction in the universe, antiproton lifetime, and the diffuse radiation

    Energy Technology Data Exchange (ETDEWEB)

    Stephens, S.A. [Tata Institute of Fundamental Research, Homi Bhabha Road, Bombay 400005 (India); Finetti, N. [Particle Astrophysics Laboratory, New Mexico State University, Las Cruces, New Mexico 88003 (United States)

    1995-07-01

    We have calculated the diffuse spectrum in the energy region between 0.1 keV and 500 MeV, which arises from the decay of antiprotons in the baryon Symmetric Universe. Comparing this with the observation, we derived a life time of {gt}2.3{times}10 {sup 24} sec for the antiproton, which is 17 orders better than the one determined from laboratory experiments. We predict a cut-off in the diffuse radiation beyond 460 MeV, and if seen, would provide evidence for the existence of antimatter domains in the universe. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

  15. Single ionization of helium by 40--3000-keV antiprotons

    Energy Technology Data Exchange (ETDEWEB)

    Andersen, L.H.; Hvelplund, P.; Knudsen, H.; Moller, S.P.; Pedersen, J.O.P.; Tang-Petersen, S.; Uggerhoj, E. (Institute of Physics, University of Aarhus, DK-8000 Aarhus C (Denmark)); Elsener, K. (CERN, CH-1211 Geneva (Switzerland)); Morenzoni, E. (PSI, CH-5234 Villigen (Switzerland))

    1990-06-01

    Measurements of single-ionization cross sections for antiproton impact on helium atoms are reported for impact energies ranging from 40 keV to 3 MeV. It is found that the measured cross sections are in good agreement with recent theoretical estimates based on the continuum-distorted-wave approximation. From a comparison with similar proton data, the ratio between antiproton and proton results is obtained. The energy dependence of this ratio is compared with various theoretical estimates and explained as a result of polarization and binding effects.

  16. Single ionization of helium by 40-3000-keV antiprotons

    Science.gov (United States)

    Andersen, L. H.; Hvelplund, P.; Knudsen, H.; Møller, S. P.; Pedersen, J. O. P.; Tang-Petersen, S.; Uggerhøj, E.; Elsener, K.; Morenzoni, E.

    1990-06-01

    Measurements of single-ionization cross sections for antiproton impact on helium atoms are reported for impact energies ranging from 40 keV to 3 MeV. It is found that the measured cross sections are in good agreement with recent theoretical estimates based on the continuum-distorted-wave approximation. From a comparison with similar proton data, the ratio between antiproton and proton results is obtained. The energy dependence of this ratio is compared with various theoretical estimates and explained as a result of polarization and binding effects.

  17. Pion, Kaon, Proton and Antiproton Production in Proton-Proton Collisions

    Science.gov (United States)

    Norbury, John W.; Blattnig, Steve R.

    2008-01-01

    Inclusive pion, kaon, proton, and antiproton production from proton-proton collisions is studied at a variety of proton energies. Various available parameterizations of Lorentz-invariant differential cross sections as a function of transverse momentum and rapidity are compared with experimental data. The Badhwar and Alper parameterizations are moderately satisfactory for charged pion production. The Badhwar parameterization provides the best fit for charged kaon production. For proton production, the Alper parameterization is best, and for antiproton production the Carey parameterization works best. However, no parameterization is able to fully account for all the data.

  18. Evidence for a Possible Proton-Antiproton Bound State from Lattice QCD

    CERN Document Server

    Loan, M

    2006-01-01

    We have used standard techniques of lattice quantum chromodynamics to look for evidence of the spin-zero six quark flavour singlet state ($J^{PC}=0^{-+}$) observed by BES Collaboration, and to determine the splitting between the mass of the possible proton-antiproton and the mass of two protons, its threshold. Ignoring quark loops and quark annihilation, we find indications that for sufficiently light quarks proton- antiproton is below the $2m_{p}$ threshold, making it a possible six-quark bound state.

  19. Proton-Antiproton Pair Production in Two-Photon Collisions at LEP

    CERN Document Server

    Achard, P; Aguilar-Benítez, M; Alcaraz, J; Alemanni, G; Allaby, James V; Aloisio, A; Alviggi, M G; Anderhub, H; Andreev, V P; Anselmo, F; Arefev, A; Azemoon, T; Aziz, T; Bagnaia, P; Bajo, A; Baksay, G; Baksay, L; Baldew, S V; Banerjee, S; Banerjee, Sw; Barczyk, A; Barillère, R; Bartalini, P; Basile, M; Batalova, N; Battiston, R; Bay, A; Becattini, F; Becker, U; Behner, F; Bellucci, L; Berbeco, R; Berdugo, J; Berges, P; Bertucci, B; Betev, B L; Biasini, M; Biglietti, M; Biland, A; Blaising, J J; Blyth, S C; Bobbink, Gerjan J; Böhm, A; Boldizsar, L; Borgia, B; Bottai, S; Bourilkov, D; Bourquin, Maurice; Braccini, S; Branson, J G; Brochu, F; Burger, J D; Burger, W J; Cai, X D; Capell, M; Cara Romeo, G; Carlino, G; Cartacci, A M; Casaus, J; Cavallari, F; Cavallo, N; Cecchi, C; Cerrada, M; Chamizo-Llatas, M; Chang, Y H; Chemarin, M; Chen, A; Chen, G; Chen, G M; Chen, H F; Chen, H S; Chiefari, G; Cifarelli, Luisa; Cindolo, F; Clare, I; Clare, R; Coignet, G; Colino, N; Costantini, S; de la Cruz, B; Cucciarelli, S; van Dalen, J A; De Asmundis, R; Déglon, P L; Debreczeni, J; Degré, A; Dehmelt, K; Deiters, K; Della Volpe, D; Delmeire, E; Denes, P; De Notaristefani, F; De Salvo, A; Diemoz, M; Dierckxsens, M; Dionisi, C; Dittmar, M; Doria, A; Dova, M T; Duchesneau, D; Duda, M; Echenard, B; Eline, A; El-Hage, A; El-Mamouni, H; Engler, A; Eppling, F J; Extermann, P; Falagán, M A; Falciano, S; Favara, A; Fay, J; Fedin, O; Felcini, M; Ferguson, T; Fesefeldt, H S; Fiandrini, E; Field, J H; Filthaut, Frank; Fisher, P H; Fisher, W; Fisk, I; Forconi, G; Freudenreich, Klaus; Furetta, C; Galaktionov, Yu; Ganguli, S N; García-Abia, P; Gataullin, M; Gentile, S; Giagu, S; Gong, Z F; Grenier, G; Grimm, O; Grünewald, M W; Guida, M; van Gulik, R; Gupta, V K; Gurtu, A; Gutay, L J; Haas, D; Hakobyan, R S; Hatzifotiadou, D; Hebbeker, T; Hervé, A; Hirschfelder, J; Hofer, H; Hohlmann, M; Holzner, G; Hou, S R; Hu, Y; Jin, B N; Jones, L W; de Jong, P; Josa-Mutuberria, I; Käfer, D; Kaur, M; Kienzle-Focacci, M N; Kim, J K; Kirkby, Jasper; Kittel, E W; Klimentov, A; König, A C; Kopal, M; Koutsenko, V F; Kräber, M H; Krämer, R W; Krüger, A; Kunin, A; Ladrón de Guevara, P; Laktineh, I; Landi, G; Lebeau, M; Lebedev, A; Lebrun, P; Lecomte, P; Lecoq, P; Le Coultre, P; Le Goff, J M; Leiste, R; Levtchenko, M; Levchenko, P M; Li, C; Likhoded, S; Lin, C H; Lin, W T; Linde, Frank L; Lista, L; Liu, Z A; Lohmann, W; Longo, E; Lü, Y S; Luci, C; Luminari, L; Lustermann, W; Ma Wen Gan; Malgeri, L; Malinin, A; Maña, C; Mans, J; Martin, J P; Marzano, F; Mazumdar, K; McNeil, R R; Mele, S; Merola, L; Meschini, M; Metzger, W J; Mihul, A; Milcent, H; Mirabelli, G; Mnich, J; Mohanty, G B; Muanza, G S; Muijs, A J M; Musicar, B; Musy, M; Nagy, S; Natale, S; Napolitano, M; Nessi-Tedaldi, F; Newman, H; Nisati, A; Nowak, H; Ofierzynski, R A; Organtini, G; Pal, I; Palomares, C; Paolucci, P; Paramatti, R; Passaleva, G; Patricelli, S; Paul, T; Pauluzzi, M; Paus, C; Pauss, Felicitas; Pedace, M; Pensotti, S; Perret-Gallix, D; Petersen, B; Piccolo, D; Pierella, F; Pioppi, M; Piroué, P A; Pistolesi, E; Plyaskin, V; Pohl, M; Pozhidaev, V; Pothier, J; Prokofev, D; Prokofiev, D O; Quartieri, J; Rahal-Callot, G; Rahaman, M A; Raics, P; Raja, N; Ramelli, R; Rancoita, P G; Ranieri, R; Raspereza, A V; Razis, P A; Ren, D; Rescigno, M; Reucroft, S; Riemann, S; Riles, K; Roe, B P; Romero, L; Rosca, A; Rosier-Lees, S; Roth, S; Rosenbleck, C; Rubio, J A; Ruggiero, G; Rykaczewski, H; Sakharov, A; Saremi, S; Sarkar, S; Salicio, J; Sánchez, E; Schäfer, C; Shchegelskii, V; Schopper, Herwig Franz; Schotanus, D J; Sciacca, C; Servoli, L; Shevchenko, S; Shivarov, N; Shoutko, V; Shumilov, E; Shvorob, A V; Son, D; Souga, C; Spillantini, P; Steuer, M; Stickland, D P; Stoyanov, B; Strässner, A; Sudhakar, K; Sultanov, G G; Sun, L Z; Sushkov, S; Suter, H; Swain, J D; Szillási, Z; Tang, X W; Tarjan, P; Tauscher, Ludwig; Taylor, L; Tellili, B; Teyssier, D; Timmermans, C; Ting, Samuel C C; Ting, S M; Tonwar, S C; Tóth, J; Tully, C; Tung, K L; Ulbricht, J; Valente, E; Van de Walle, R T; Vásquez, R; Veszpremi, V; Vesztergombi, G; Vetlitskii, I; Vicinanza, D; Viertel, Gert M; Villa, S; Vivargent, M; Vlachos, S; Vodopyanov, I; Vogel, H; Vogt, H; Vorobev, I; Vorobyov, A A; Wadhwa, M; Wang, Q; Wang, X L; Wang, Z M; Weber, M; Wienemann, P; Wilkens, H; Wynhoff, S; Xia, L; Xu, Z Z; Yamamoto, J; Yang, B Z; Yang, C G; Yang, H J; Yang, M; Yeh, S C; Zalite, A; Zalite, Yu; Zhang, Z P; Zhao, J; Zhu, G Y; Zhu, R Y; Zhuang, H L; Zichichi, A; Zimmermann, B; Zöller, M

    2003-01-01

    The reaction e+e- -> e+e- proton antiproton is studied with the L3 detector at LEP. The analysis is based on data collected at e+e- center-of-mass energies from 183 GeV to 209 GeV, corresponding to an integrated luminosity of 667 pb-1. The gamma gamma -> proton antiproton differential cross section is measured in the range of the two-photon center-of-mass energy from 2.1 GeV to 4.5 GeV. The results are compared to the predictions of the three-quark and quark-diquark models.

  20. The Potential Stopping Power of Student Photographs.

    Science.gov (United States)

    Konkle, Bruce E.

    1997-01-01

    Suggests that capturing photographs that have "stopping power" should not be an impossible task, but a reality for student photographers. Lists 19 recent publications and web sites on photography and photojournalism. Discusses ways for scholastic photographers to take pictures with stopping power. (RS)

  1. 14 CFR 29.675 - Stops.

    Science.gov (United States)

    2010-01-01

    ... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Design and Construction Control Systems § 29.675 Stops. (a) Each... the loads corresponding to the design conditions for the system. (d) For each main rotor blade— (1) Stops that are appropriate to the blade design must be provided to limit travel of the blade about...

  2. 14 CFR 27.675 - Stops.

    Science.gov (United States)

    2010-01-01

    ... STANDARDS: NORMAL CATEGORY ROTORCRAFT Design and Construction Control Systems § 27.675 Stops. (a) Each... the loads corresponding to the design conditions for the system. (d) For each main rotor blade— (1) Stops that are appropriate to the blade design must be provided to limit travel of the blade about...

  3. Variance optimal stopping for geometric Levy processes

    DEFF Research Database (Denmark)

    Gad, Kamille Sofie Tågholt; Pedersen, Jesper Lund

    2015-01-01

    The main result of this paper is the solution to the optimal stopping problem of maximizing the variance of a geometric Lévy process. We call this problem the variance problem. We show that, for some geometric Lévy processes, we achieve higher variances by allowing randomized stopping. Furthermore...

  4. Stop the Violence: Overcoming Self-Destruction.

    Science.gov (United States)

    George, Nelson, Ed.

    The story of the Stop the Violence movement among rap music artists and music industry colleagues is told, along with the story of a video that was produced as part of this initiative. The Stop the Violence project grew out of the reaction to violence among concert goers at a 1987 rap concert on Long Island (New York). Rap musicians have joined…

  5. Electron and Positron Stopping Powers of Materials

    Science.gov (United States)

    SRD 7 NIST Electron and Positron Stopping Powers of Materials (PC database for purchase)   The EPSTAR database provides rapid calculations of stopping powers (collisional, radiative, and total), CSDA ranges, radiation yields and density effect corrections for incident electrons or positrons with kinetic energies from 1 keV to 10 GeV, and for any chemically defined target material.

  6. Addressing production stops in the food industry

    DEFF Research Database (Denmark)

    Hansen, Zaza Nadja Lee; Herbert, Luke Thomas; Jacobsen, Peter

    2014-01-01

    This paper investigates the challenges in the food industry which causes the production lines to stop, illustrated by a case study of an SME size company in the baked goods sector in Denmark. The paper proposes key elements this sector needs to be aware of to effectively address production stops......, and gives examples of the unique challenges faced by the SME food industry....

  7. Stimulus devaluation induced by stopping action.

    Science.gov (United States)

    Wessel, Jan R; O'Doherty, John P; Berkebile, Michael M; Linderman, David; Aron, Adam R

    2014-12-01

    Impulsive behavior in humans partly relates to inappropriate overvaluation of reward-associated stimuli. Hence, it is desirable to develop methods of behavioral modification that can reduce stimulus value. Here, we tested whether one kind of behavioral modification--the rapid stopping of actions in the face of reward-associated stimuli--could lead to subsequent devaluation of those stimuli. We developed a novel paradigm with three consecutive phases: implicit reward learning, a stop-signal task, and an auction procedure. In the learning phase, we associated abstract shapes with different levels of reward. In the stop-signal phase, we paired half those shapes with occasional stop-signals, requiring the rapid stopping of an initiated motor response, while the other half of shapes was not paired with stop signals. In the auction phase, we assessed the subjective value of each shape via willingness-to-pay. In 2 experiments, we found that participants bid less for shapes that were paired with stop-signals compared to shapes that were not. This suggests that the requirement to try to rapidly stop a response decrements stimulus value. Two follow-on control experiments suggested that the result was specifically due to stopping action rather than aversiveness, effort, conflict, or salience associated with stop signals. This study makes a theoretical link between research on inhibitory control and value. It also provides a novel behavioral paradigm with carefully operationalized learning, treatment, and valuation phases. This framework lends itself to both behavioral modification procedures in clinical disorders and research on the neural underpinnings of stimulus devaluation.

  8. Gas Electron multipliers for low energy beams

    CERN Document Server

    Arnold, F; Ropelewski, L; Spanggaard, J; Tranquille, G

    2010-01-01

    Gas Electron Multipliers (GEM) find their way to more and more applications in beam instrumentation. Gas Electron Multiplication uses a very similar physical phenomenon to that of Multi Wire Proportional Chambers (MWPC) but for small profile monitors they are much more cost efficient both to produce and to maintain. This paper presents the new GEM profile monitors intended to replace the MWPCs currently used at CERN’s low energy Antiproton Decelerator (AD). It will be shown how GEMs overcome the documented problems of profile measurements with MWPCs for low energy beams, where the interaction of the beam with the detector has a large influence on the measured profile. Results will be shown of profile measurements performed at 5 MeV using four different GEM prototypes, with discussion on the possible use of GEMs at even lower energies needed at the AD in 2013.

  9. The Fermilab Main Injector: high intensity operation and beam loss control

    CERN Document Server

    Brown, Bruce C; Capista, David; Chou, Weiren; Kourbanis, Ioanis; Morris, Denton K; Seiya, Kiyomi; Wu, Guan Hong; Yang, Ming-Jen

    2013-01-01

    From 2005 through 2012, the Fermilab Main Injector provided intense beams of 120 GeV protons to produce neutrino beams and antiprotons. Hardware improvements in conjunction with improved diagnostics allowed the system to reach sustained operation at ~400 kW beam power. Transmission was very high except for beam lost at or near the 8 GeV injection energy where 95% beam transmission results in about 1.5 kW of beam loss. By minimizing and localizing loss, residual radiation levels fell while beam power was doubled. Lost beam was directed to either the collimation system or to the beam abort. Critical apertures were increased while improved instrumentation allowed optimal use of available apertures. We will summarize the improvements required to achieve high intensity, the impact of various loss control tools and the status and trends in residual radiation in the Main Injector.

  10. Buffer-gas cooling of antiprotonic helium to 1.5 to 1.7 K, and antiproton-to–electron mass ratio

    CERN Document Server

    Hori, Masaki; Sótér, Anna; Barna, Daniel; Dax, Andreas; Hayano, Ryugo; Kobayashi, Takumi; Murakami, Yohei; Todoroki, Koichi; Yamada, Hiroyuki; Horváth, Dezső; Venturelli, Luca

    2016-01-01

    Charge, parity, and time reversal (CPT) symmetry implies that a particle and its antiparticle have the same mass. The antiproton-to-electron mass ratio Embedded Image can be precisely determined from the single-photon transition frequencies of antiprotonic helium. We measured 13 such frequencies with laser spectroscopy to a fractional precision of 2.5 × 10−9 to 16 × 10−9. About 2 × 109 antiprotonic helium atoms were cooled to temperatures between 1.5 and 1.7 kelvin by using buffer-gas cooling in cryogenic low-pressure helium gas; the narrow thermal distribution led to the observation of sharp spectral lines of small thermal Doppler width. The deviation between the experimental frequencies and the results of three-body quantum electrodynamics calculations was reduced by a factor of 1.4 to 10 compared with previous single-photon experiments. From this, Embedded Image was determined as 1836.1526734(15), which agrees with a recent proton-to-electron experimental value within 8 × 10−10.

  11. Simulations of the new cryogenic gas filled stopping cell for the low energy branch of the Super-FRS at FAIR

    Energy Technology Data Exchange (ETDEWEB)

    Reiter, Moritz Pascal; Schaefer, Daniel [Justus-Liebig-Universitaet Giessen (Germany); Dickel, Timo; Plass, Wolfgang; Geissel, Hans; Scheidenberger, Christoph [Justus-Liebig-Universitaet Giessen (Germany); GSI, Darmstadt (Germany); Collaboration: FRS Ion Catcher-Collaboration

    2012-07-01

    At the low energy branch of the Super-FRS at FAIR exotic nuclei will be produced at relativistic energies, slowed down, thermalized and provided as a low energy beam to high precision experiments. The ions are stopped in a cryogenic stopping cell in high density helium gas. In order to guide the development of the new cryogenic stopping cell and to study the performance of the new techniques used, numerical simulations of the stopping cell have been performed. A parameter study of the RF carpet has been done and optimized working parameters for the stopping cell have been found. The simulation results show good agreement with the first offline and online experiments of the cryogenic stopping cell obtained at the FRS Ion Catcher at GSI. For the first time cryogenic operation of a stopping cell with a radio frequency carpet and hitherto unreached helium densities have been demonstrated.

  12. Toward a cold electron beam in the Fermilab's Electron Cooler

    Energy Technology Data Exchange (ETDEWEB)

    Vitali S. Tupikov et al.

    2004-05-12

    Fermilab is developing a high-energy electron cooling system to cool 8.9-GeV/c antiprotons in the Recycler ring [1]. Cooling of antiprotons requires a round electron beam with a small angular spread propagating through 20-m long cooling section with a kinetic energy of 4.3 MeV. To confine the electron beam tightly and to keep its transverse angles below 0.1 mrad, the cooling section will be immersed into a solenoidal field of 50-150G. This paper describes the technique of measuring and adjusting the magnetic field quality in the cooling section and presents preliminary results of beam quality measurements in the cooler prototype.

  13. Perspective study of exotics and flavour baryons in antiproton-proton annihilation and proton-proton collisions

    Science.gov (United States)

    Barabanov, Mikhail; Vodopyanov, Alexander

    2016-07-01

    Abstract. The spectroscopy of exotic states with hidden charm is discussed. Together with charmonium, these provide a good tool for testing theories of the strong interactions including both perturbative and non-perturbative QCD, lattice QCD, potential and other phenomenological models. An elaborated analysis of exotics spectrum is given, and attempts to interpret recent experimentally observed states with masses above the DD̅ threshold region are considered. Experimental results from different collaborations (BES, BaBar, Belle, LHCb) are analyzed with special attention given to recently discovered hidden charm states. Some of these states can be interpreted as higher-lying charmonium states and others as tetraquarks with hidden charm. It has been shown that charged/neutral tetraquarks must have their neutral/charge partners with mass values differ by at most a few MeV/c2, hypotheses that tend to coincide with those proposed by Maiani and Polosa. However, measurements of different decay modes are needed before firm conclusions can be made. These data can be derived directly from the experiments using ahigh quality antiproton beam with momentum up to 15 GeV/c and proton-proton collisions with momentum up to 26 GeV/c. DD

  14. Radionuclides in the Cooling Water Systems for the NuMi Beamline and the Antiproton Production Target Station at Fermilab

    CERN Document Server

    Matsumura, Hiroshi; Bessho, Kotaro; Sekimoto, Shun; Yashima, Hiroshi; Kasugai, Yoshimi; Matsuda, Norihiro; Sakamoto, Yukio; Nakashima, Hiroshi; Oishi, Koji; Boehnlein, David; Lauten, Gary; Leveling, Anthony; Mokhov, Nikolai; Vaziri, Kamran

    2014-01-01

    At the 120-GeV proton accelerator facilities of Fermilab, USA, water samples were collected from the cooling water systems for the target, magnetic horn1, magnetic horn2, decay pipe, and hadron absorber at the NuMI beamline as well as from the cooling water systems for the collection lens, pulse magnet and collimator, and beam absorber at the antiproton production target station, just after the shutdown of the accelerators for a maintenance period. Specific activities of {\\gamma} -emitting radionuclides and 3H in these samples were determined using high-purity germanium detectors and a liquid scintillation counter. The cooling water contained various radionuclides depending on both major and minor materials in contact with the water. The activity of the radionuclides depended on the presence of a deionizer. Specific activities of 3H were used to estimate the residual rates of 7Be. The estimated residual rates of 7Be in the cooling water were approximately 5% for systems without deionizers and less than 0.1% f...

  15. Sudden stopping in patients with cerebellar ataxia.

    Science.gov (United States)

    Serrao, Mariano; Conte, Carmela; Casali, Carlo; Ranavolo, Alberto; Mari, Silvia; Di Fabio, Roberto; Perrotta, Armando; Coppola, Gianluca; Padua, Luca; Monamì, Stefano; Sandrini, Giorgio; Pierelli, Francesco

    2013-10-01

    Stopping during walking, a dynamic motor task frequent in everyday life, is very challenging for ataxic patients, as it reduces their gait stability and increases the incidence of falls. This study was conducted to analyse the biomechanical characteristics of upper and lower body segments during abrupt stopping in ataxic patients in order to identify possible strategies used to counteract the instability in the sagittal and frontal plane. Twelve patients with primary degenerative cerebellar ataxia and 12 age- and sex-matched healthy subjects were studied. Time-distance parameters, dynamic stability of the centre of mass, upper body measures and lower joint kinematic and kinetic parameters were analysed. The results indicate that ataxic patients have a great difficulty in stopping abruptly during walking and adopt a multi-step stopping strategy, occasionally with feet parallel, to compensate for their inability to coordinate the upper body and to generate a well-coordinated lower limb joint flexor-extensor pattern and appropriate braking forces for progressively decelerating the progression of the body in the sagittal plane. A specific rehabilitation treatment designed to improve the ability of ataxic patients to transform unplanned stopping into planned stopping, to coordinate upper body and to execute an effective flexion-extension pattern of the hip and knee joints may be useful in these patients in order to improve their stopping performance and prevent falls.

  16. Cryogenic stopping cell for photofission fragments at the ELI-NP facility

    Energy Technology Data Exchange (ETDEWEB)

    Constantin, P., E-mail: paul.constantin@eli-np.ro; Balabanski, D. L. [ELI-NP, IFIN-HH, Str. Reactorului 30, 077125 Bucharest Magurele (Romania); Cuong, P. V. [Centre of Nuclear Physics, Institute of Physics, No. 10, Daotan, Thu le, Badinh, Hanoi (Viet Nam)

    2015-10-15

    The brilliant gamma beam at the future Extreme Light Infrastructure - Nuclear Physics (ELI-NP) facility will be used to generate a beam of exotic neutron-rich isotopes via photofission of actinide targets. We present simulations with the Geant4 toolkit of the photofission process for the design and optimization of the expected performance parameters of the Cryogenic Stopping Cell (CSC). The CSC will be used to extract the photofission fragments into the secondary beam of about 10{sup 6} ions/s. We propose an experimental program to study refractory neutron-rich isotopes.

  17. Ion optics and beam dynamics optimization at the HESR storage ring for the SPARC experiments with highly charged heavy ions

    Energy Technology Data Exchange (ETDEWEB)

    Kovalenko, Oleksandr

    2015-06-24

    The High-Energy Storage Ring (HESR) is a part of an upcoming International Facility for Antiproton and Ion Research (FAIR) at GSI in Darmstadt. A key part of a scientific program, along with antiproton physics, will be physics with highly-charged heavy ions. Phase-space cooled beams together with fixed internal target will provide an excellent environment for storage ring experiments at the HESR for the SPARC collaboration. Until recently, however, the existing ion optical lattice for the HESR was designed only for the experiments with antiproton beams. The thesis presents a new ion optical mode developed specifically for the operation of the HESR with highly charged heavy ions. The presence of the errors, such as beam momentum spread, magnetic field impurities or magnets misalignments, leads to disruption of beam dynamics: exciting of resonant motion and loss of beam stability. Within the paper, these effects are investigated with the help of numerical codes for particle accelerator design and simulation MAD-X and MIRKO. A number of correction techniques are applied to minimize the nonlinear impact on the beam dynamics and improve the experimental conditions. The application of the analytical and numerical tools is demonstrated in the experiment with uranium U{sup 90+} beam at the existing storage ring ESR, GSI.

  18. Multifragmentation with GeV light-ion beams

    CERN Document Server

    Kwiatkowski, K; Wang, G; Lefort, T; Bracken, D S; Cornell, E; Foxford, E R; Ginger, D S; Viola, V E; Yoder, N R; Korteling, R G; Pollacco, E C; Legrain, R; Volant, C; Gimeno-Nogues, F; Laforest, R; Martin, E; Ramakrishnan, E; Rowland, D; Ruangma, A; Winchester, E M; Yennello, S J; Lynch, W G; Tsang, M B; Xi, H; Breuer, H; Morley, K B; Gushue, S; Remsberg, L P; Pienkowski, L; Brzychczyk, J; Botvina, A; Friedman, W A

    1999-01-01

    Multifragmentation studies with GeV light-ion beams indicate that for the most violent collisions, complex fragments are emitted during expansion of the hot source, followed by near simultaneous breakup of the system near rho/rho sub o approx ((1)/(3)). The results are compared with hybrid INC/EES and INC/SMM models. Preliminary data for the 8 GeV/c pi sup - and p-bar reactions on sup 1 sup 9 sup 7 Au show enhanced deposition energy for the antiproton beam.

  19. Polarization of a stored beam by spin-filtering

    Energy Technology Data Exchange (ETDEWEB)

    Augustyniak, W. [National Centre for Nuclear Research, 00681 Warsaw (Poland); Barion, L. [Universita di Ferrara and INFN, 44122 Ferrara (Italy); Barsov, S. [St. Petersburg Nuclear Physics Institute, 188350 Gatchina (Russian Federation); Bechstedt, U. [Institut fuer Kernphysik, Forschungszentrum Juelich GmbH, 52425 Juelich (Germany); Juelich Center for Hadron Physics, 52425 Juelich (Germany); Benati, P.; Bertelli, S.; Carassiti, V. [Universita di Ferrara and INFN, 44122 Ferrara (Italy); Chiladze, D. [High Energy Physics Institute, Tbilisi State University, 0186 Tbilisi, Georgia (United States); Ciullo, G.; Contalbrigo, M.; Dalpiaz, P.F. [Universita di Ferrara and INFN, 44122 Ferrara (Italy); Dymov, S. [Physikalische Institute II, Universitaet Erlangen-Nuernberg, 91058 Erlangen (Germany); Laboratory of Nuclear Problems, Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Engels, R. [Institut fuer Kernphysik, Forschungszentrum Juelich GmbH, 52425 Juelich (Germany); Juelich Center for Hadron Physics, 52425 Juelich (Germany); Erwen, W. [Juelich Center for Hadron Physics, 52425 Juelich (Germany); Zentralinstitut fuer Elektronik, Forschungszentrum Juelich GmbH, 52425 Juelich (Germany); Fiorini, M. [Universita di Ferrara and INFN, 44122 Ferrara (Italy); and others

    2012-11-15

    The PAX Collaboration has successfully performed a spin-filtering experiment with protons at the COSY-ring. The measurement allowed the determination of the spin-dependent polarizing cross section, that compares well with the theoretical prediction from the nucleon-nucleon potential. The test confirms that spin-filtering can be adopted as a method to polarize a stored beam and that the present interpretation of the mechanism in terms of the proton-proton interaction is correct. The outcome of the experiment is of utmost importance in view of the possible application of the method to polarize a beam of stored antiprotons.

  20. Measurement of 0.25-3.2 GeV antiprotons in the cosmic radiation

    DEFF Research Database (Denmark)

    Mitchell, J.W.; Barbier, L.M.; Christian, E.R.;

    1996-01-01

    The balloon-borne Isotope Matter-Antimatter Experiment (IMAX) was flown from Lynn Lake, Manitoba, Canada on 16-17 July 1992. Using velocity and magnetic rigidity to determine mass, we have directly measured the abundances of cosmic ray antiprotons and protons in the energy range from 0.25 to 3.2 ...

  1. Closing in on mass-degenerate dark matter scenarios with antiprotons and direct detection

    Energy Technology Data Exchange (ETDEWEB)

    Garny, Mathias [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Ibarra, Alejandro; Pato, Miguel; Vogl, Stefan [Technische Univ. Muenchen, Garching (Germany). Physik-Department

    2012-07-15

    Over the last years both cosmic-ray antiproton measurements and direct dark matter searches have proved particularly effective in constraining the nature of dark matter candidates. The present work focusses on these two types of constraints in a minimal framework which features a Majorana fermion as the dark matter particle and a scalar that mediates the coupling to quarks. Considering a wide range of coupling schemes, we derive antiproton and direct detection constraints using the latest data and paying close attention to astrophysical and nuclear uncertainties. Both signals are strongly enhanced in the presence of degenerate dark matter and scalar masses, but we show that the effect is especially dramatic in direct detection. Accordingly, the latest direct detection limits take the lead over antiprotons. We find that antiproton and direct detection data set stringent lower limits on the mass splitting, reaching 19% at a 300 GeV dark matter mass for a unity coupling. Interestingly, these limits are orthogonal to ongoing collider searches at the Large Hadron Collider, making it feasible to close in on degenerate dark matter scenarios within the next years.

  2. Antiproton-to-proton ratios for ALICE heavy-ion collisions

    Energy Technology Data Exchange (ETDEWEB)

    Tawfik, A., E-mail: atawfik@cern.ch [Egyptian Center for Theoretical Physics (ECTP), MTI University, Cairo (Egypt)

    2011-06-01

    Assuming that the final state of hadronization takes place along the freezeout line, which is defined by a constant entropy density, the antiproton-to-proton ratios produced in heavy-ion collisions are studied in framework of the hadron resonance gas (HRG) model. A phase transition from quark-gluon plasma to hadrons, a hadronization, has been conjectured in order to allow modifications in the phase-space volume and thus in the single-particle distribution function. Implementing both modifications in the grand-canonical partition function and taking into account the experimental acceptance in the heavy-ion collisions, the antiproton-to-proton ratios over center-of-mass energies {radical}(s) ranging from AGS to RHIC are very well reproduced by the HRG model. Comparing with the same particle ratios in pp collisions results in a gradually narrowing discrepancy with increasing {radical}(s). At LHC energy, the ALICE antiproton-to-proton ratios in the pp collisions turn to be very well described by the HRG model as well. It is likely that the ALICE AA-program will produce the same antiproton-to-proton ratios as the pp-one. Furthermore, the ratio gets very close to unity indicating that the matter-antimatter asymmetry nearly vanishes. The chemical potential calculated at this energy strengthens the assumption of almost fully matter-antimatter symmetry up to the LHC energy.

  3. Status Report for Experiment AD-4/ACE Biological Effectiveness of Antiproton Annihilation

    CERN Document Server

    Holzscheiter, M H; Angelopoulos, Angelo; Bassler, Niels; Beyer, Gerd; Currell, Fred; De Marco, John; Doser, Michael; Hajdukovic, Dragan; Hartley, Oliver; Kavanagh, Joy; Iwamoto, Kei; Jäkel, Oliver; Kantemiris, Ioannis; Knudsen, Helge; Kovacevic, Sandra; McBride, Bill; Møller, Søren Pape; Overgaard, Jens; Petersen, Jørgen; Ratib, Osman; Schettino, Giuseppe; Timson, David; Singers-Sørensen, Brita; Solberg, Timothy; Vranjes, Sanja; Wouters, Brad

    2009-01-01

    Status report for experiment AD-4/ACE showing recent progress in RBE measurements for V79 Chinese Hamster cells irradiated with antiprotons. Also discussed are initial test experiments using the H2AX assay to study DNA damage to cells and initial experiments using liquid ionization chambers.

  4. Commissioning of the KOALA experiment by proton beam at COSY

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Qiang [Institute of Modern Physics, CAS, Lanzhou (China); Forschungszentrum Juelich (Germany); Xu, Huagen; Ritman, James [Forschungszentrum Juelich (Germany)

    2015-07-01

    The KOALA Experiment at HESR is dedicated to measure counts of antiproton-proton elastic scattering in a large range of squared 4-momentum transfer, t, from 0.0008 to 0.1 GeV{sup 2}. The goal of the KOALA Experiment is to determine the antiproton-proton elastic scattering forward parameters (i.e. σ{sub tot}, ρ and b) to save as a calibration for the anti PANDA luminosity detector. The scattered antiprotons will be measured by tracking detectors in the forward angle region and the recoil protons will be detected with energy detectors near polar angles of 90 . One recoil arm has been built and commissioned at COSY by measuring proton-proton elastic scattering in the beam momentum region from 1.7 to 3.2 GeV/c. The data at beam momentum of 2.8 GeV/c and 3.2 GeV/c have been analyzed. Preliminary results of the analysis are presented.

  5. Monte Carlo based water/medium stopping-power ratios for various ICRP and ICRU tissues.

    Science.gov (United States)

    Fernández-Varea, José M; Carrasco, Pablo; Panettieri, Vanessa; Brualla, Lorenzo

    2007-11-07

    Water/medium stopping-power ratios, s(w,m), have been calculated for several ICRP and ICRU tissues, namely adipose tissue, brain, cortical bone, liver, lung (deflated and inflated) and spongiosa. The considered clinical beams were 6 and 18 MV x-rays and the field size was 10 x 10 cm(2). Fluence distributions were scored at a depth of 10 cm using the Monte Carlo code PENELOPE. The collision stopping powers for the studied tissues were evaluated employing the formalism of ICRU Report 37 (1984 Stopping Powers for Electrons and Positrons (Bethesda, MD: ICRU)). The Bragg-Gray values of s(w,m) calculated with these ingredients range from about 0.98 (adipose tissue) to nearly 1.14 (cortical bone), displaying a rather small variation with beam quality. Excellent agreement, to within 0.1%, is found with stopping-power ratios reported by Siebers et al (2000a Phys. Med. Biol. 45 983-95) for cortical bone, inflated lung and spongiosa. In the case of cortical bone, s(w,m) changes approximately 2% when either ICRP or ICRU compositions are adopted, whereas the stopping-power ratios of lung, brain and adipose tissue are less sensitive to the selected composition. The mass density of lung also influences the calculated values of s(w,m), reducing them by around 1% (6 MV) and 2% (18 MV) when going from deflated to inflated lung.

  6. Tevatron Beam Position Monitor Upgrade

    CERN Document Server

    Wolbers, Stephen; Barker, B; Bledsoe, S; Boes, T; Bowden, Mark; Cancelo, Gugstavo I; Dürling, G; Forster, B; Haynes, B; Hendricks, B; Kasza, T; Kutschke, Robert K; Mahlum, R; Martens, Michael A; Mengel, M; Olsen, M; Pavlicek, V; Pham, T; Piccoli, Luciano; Steimel, Jim; Treptow, K; Votava, Margaret; Webber, Robert C; West, B; Zhang, D

    2005-01-01

    The Tevatron Beam Position Monitor (BPM) readout electronics and software have been upgraded to improve measurement precision, functionality and reliability. The original system, designed and built in the early 1980s, became inadequate for current and future operations of the Tevatron. The upgraded system consists of 960 channels of new electronics to process analog signals from 240 BPMs, new front-end software, new online and controls software, and modified applications to take advantage of the improved measurements and support the new functionality. The new system reads signals from both ends of the existing directional stripline pickups to provide simultaneous proton and antiproton position measurements. Measurements using the new system are presented that demonstrate its improved resolution and overall performance.

  7. I Search of Narrow Proton-Antiproton Bound States: High Resolution Gamma and Charged Flow Pion Spectra from Protonium.

    Science.gov (United States)

    Petridou, Chariclia I.

    We studied the pp annihilations at rest looking for narrow bound states in the proton-antiproton system. We looked, with high energy resolution, for radiative and pionic transitions in the gamma and charged pion spectra. The detector for the (gamma)(--->)e+e- and the (pi)('(+OR-)) was a magnetic pair spectrometer. The directions of the incident particles (e(+OR-) and (pi)(+OR-)) were determined by a drift chamber module in front of the magnet and the final directions of the particles, if reflected in the magnet, by the same chamber; if transversing the magnet, by an identical module at the rear of the magnet. The momentum was calculated from the directions of the particle. The following gamma spectra were obtained. Gammas with both e+, e- reflected in the magnet at a field of about 6 Kgauss (RR-gammas). That covers the region between 80 and 180 MeV, corresponding to a missing mass 1794 to 1686 MeV/c. The energy resolution is about 2.5 MeV ((sigma)) at 129 MeV (confirmed by the observed Panofsky gammas from stopping (pi)('-)p data) and 5 MeV ((sigma)) at 80 MeV. We have no evidence for narrow peaks except for the Panofsky gamma produced with a branching ratio of 3.3 x 10('-3) from (pi)('-) stops in the target. Upper limits for (gamma) -transitions in the region between 80 to 180 MeV were set at about 10('-3). Gammas with one e+(e-) reflected and the other transversing the magnet (RP-gammas) for fields of about 6 and 12 Kgauss, covering the region (GREATERTHEQ) 200 MeV, which corresponds to missing mass (LESSTHEQ) 1664 MeV/c('2). The gamma energy resolution in MeV is 51(.)E('2) (GeV) and 25.5(.)E('2)(GeV) for the low and high field respectively. Finally the charged pion spectra for those transversing the magnet are given for both magnet settings and as a function of charge multiplicity, covering the momentum region from (GREATERTHEQ) 150 MeV/c. The momentum resolution is the same as that for the RP-gammas. The two body annihilations (pi)('+)(pi)('-) and (pi

  8. Fuel Target Implosion in Ion beam Inertial Confinement Fusion

    CERN Document Server

    Kawata, Shigeo

    2015-01-01

    The numerical results for the fuel target implosion are presented in order to clarify the target physics in ion beam inertial fusion. The numerical analyses are performed for a direct-driven ion beam target. In the paper the following issues are studied: the beam obliquely incidence on the target surface, the plasma effect on the beam-stopping power, the beam particle energy, the beam time duration, the target radius, the beam input energy and the non-uniformity effect on the fuel target performance. In this paper the beam ions are protons.

  9. Determination of Beam Intensity and Position in a Particle Accelerator

    CERN Document Server

    Kasprowicz, Grzegorz; Raich, Uli

    2011-10-04

    A subject of the thesis is conception, design, implementation, tests and deployment of new position measurement system of particle bunch in the CERN PS circular accelerator. The system is based on novel algorithms of particle position determination. The Proton Synchrotron accelerator (PS), installed at CERN†, although commissioned in 1959, still plays a central role in the production of beams for the Antiproton Decelerator, Super Proton Synchrotron, various experimental areas and for the Large Hadron Collider (LHC)‡. The PS produces beams of different types of particles, mainly protons, but also various species of ions. Almost all these particle beams pass through the PS. The quality of the beams delivered to the LHC has a direct impact on the effective luminosity, and therefore the performance of the instrumentation of the PS is of great importance. The old trajectory and orbit measurement system of the PS is dated back to 1988 and no longer fulfilled present day requirements. It used 40 beam posi...

  10. Determination of beam intensity and position in a particle accelerator

    CERN Document Server

    Kasprowicz, G

    2011-01-01

    A subject of the thesis is conception, design, implementation, tests and deployment of new position measurement system of particle bunch in the CERN PS circular accelerator. The system is based on novel algorithms of particle position determination. The Proton Synchrotron accelerator (PS), installed at CERN, although commissioned in 1959, still plays a central role in the production of beams for the Antiproton Decelerator, Super Proton Synchrotron, various experimental areas and for the Large Hadron Collider (LHC). The PS produces beams of different types of particles, mainly protons, but also various species of ions. Almost all these particle beams pass through the PS. The quality of the beams delivered to the LHC has a direct impact on the effective luminosity, and therefore the performance of the instrumentation of the PS is of great importance. The old trajectory and orbit measurement system of the PS is dated back to 1988 and no longer fulfilled present day requirements. It used 40 beam position monitors...

  11. Imagine stopping the progression of Alzheimer's

    Science.gov (United States)

    ... Issue Past Issues Imagine stopping the progression of Alzheimer's Past Issues / Fall 2006 Table of Contents For ... I have friends and loved ones suffering from Alzheimer's. But I can imagine… and hope for… a ...

  12. An Update on the Depth-Dose Curve of Antiprotons

    DEFF Research Database (Denmark)

    Taasti, Vicki Trier; Holzscheiter, Michael H.; Knudsen, Helge

    in water. The experimental results are compared with the Monte Carlo particle transport code SHIELD-HIT12A. Contrary to [1], here the full ionization chamber is simulated and the dose is scored in the ionization chamber air gap. Stopping power ratios are determined as well in order to translate...... the simulated dose to dose-to-water formalism. Results: Generally, the experimental data are in good agreement with the simulated dose on an absolute scale in the plateau region. However some deviations are found near the annihilation peak. A full geometric description of the ionization chamber simulation...... improves the situation, in particular on the upstream side of the Bragg-peak. This is attributed to a different spectrum of annihilation products created in the entrance window of the ionization chamber in comparison to the case of simply simulating annihilation taking place on water. Yet, a large portion...

  13. Ion beam analysis fundamentals and applications

    CERN Document Server

    Nastasi, Michael; Wang, Yongqiang

    2015-01-01

    Ion Beam Analysis: Fundamentals and Applications explains the basic characteristics of ion beams as applied to the analysis of materials, as well as ion beam analysis (IBA) of art/archaeological objects. It focuses on the fundamentals and applications of ion beam methods of materials characterization.The book explains how ions interact with solids and describes what information can be gained. It starts by covering the fundamentals of ion beam analysis, including kinematics, ion stopping, Rutherford backscattering, channeling, elastic recoil detection, particle induced x-ray emission, and nucle

  14. Inseparability of Go and Stop in Inhibitory Control: Go Stimulus Discriminability Affects Stopping Behavior

    Directory of Open Access Journals (Sweden)

    Ning eMa

    2016-03-01

    Full Text Available Inhibitory control, the ability to stop or modify preplanned actions under changing task conditions, is an important component of cognitive functions. Two lines of models of inhibitory control have previously been proposed for human response in the classical stop-signal task, in which subjects must inhibit a default go response upon presentation of an infrequent stop signal: (1 the race model, which posits two independent go and stop processes that race to determine the behavioral outcome, go or stop; and (2 an optimal decision-making model, which posits that observers decides whether and when to go based on continually (Bayesian updated information about both the go and stop stimuli. In this work, we probe the relationship between go and stop processing by explicitly manipulating the discrimination difficulty of the go stimulus. While the race model assumes the go and stop processes are independent, and therefore go stimulus discriminability should not affect the stop stimulus processing, we simulate the optimal model to show that it predicts harder go discrimination results in a longer go reaction time (RT, a lower stop error rate, as well as a faster stop-signal RT. We then present novel behavioral data that validate these model predictions. The results thus favor a fundamentally inseparable account of go and stop processing, in a manner consistent with the optimal model, and contradicting the independence assumption of the race model. More broadly, our findings contribute to the growing evidence that the computations underlying inhibitory control are systematically modulated by cognitive influences in a Bayes-optimal manner, thus opening new avenues for interpreting neural responses underlying inhibitory control.

  15. Inseparability of Go and Stop in Inhibitory Control: Go Stimulus Discriminability Affects Stopping Behavior.

    Science.gov (United States)

    Ma, Ning; Yu, Angela J

    2016-01-01

    Inhibitory control, the ability to stop or modify preplanned actions under changing task conditions, is an important component of cognitive functions. Two lines of models of inhibitory control have previously been proposed for human response in the classical stop-signal task, in which subjects must inhibit a default go response upon presentation of an infrequent stop signal: (1) the race model, which posits two independent go and stop processes that race to determine the behavioral outcome, go or stop; and (2) an optimal decision-making model, which posits that observers decides whether and when to go based on continually (Bayesian) updated information about both the go and stop stimuli. In this work, we probe the relationship between go and stop processing by explicitly manipulating the discrimination difficulty of the go stimulus. While the race model assumes the go and stop processes are independent, and therefore go stimulus discriminability should not affect the stop stimulus processing, we simulate the optimal model to show that it predicts harder go discrimination should result in longer go reaction time (RT), lower stop error rate, as well as faster stop-signal RT. We then present novel behavioral data that validate these model predictions. The results thus favor a fundamentally inseparable account of go and stop processing, in a manner consistent with the optimal model, and contradicting the independence assumption of the race model. More broadly, our findings contribute to the growing evidence that the computations underlying inhibitory control are systematically modulated by cognitive influences in a Bayes-optimal manner, thus opening new avenues for interpreting neural responses underlying inhibitory control.

  16. When the brain simulates stopping: Neural activity recorded during real and imagined stop-signal tasks.

    Science.gov (United States)

    González-Villar, Alberto J; Bonilla, F Mauricio; Carrillo-de-la-Peña, María T

    2016-10-01

    It has been suggested that mental rehearsal activates brain areas similar to those activated by real performance. Although inhibition is a key function of human behavior, there are no previous reports of brain activity during imagined response cancellation. We analyzed event-related potentials (ERPs) and time-frequency data associated with motor execution and inhibition during real and imagined performance of a stop-signal task. The ERPs characteristic of stop trials-that is, the stop-N2 and stop-P3-were also observed during covert performance of the task. Imagined stop (IS) trials yielded smaller stop-N2 amplitudes than did successful stop (SS) and unsuccessful stop (US) trials, but midfrontal theta power similar to that in SS trials. The stop-P3 amplitude for IS was intermediate between those observed for SS and US. The results may be explained by the absence of error-processing and correction processes during imagined performance. For go trials, real execution was associated with higher mu and beta desynchronization over motor areas, which confirms previous reports of lower motor activation during imagined execution and also with larger P3b amplitudes, probably indicating increased top-down attention to the real task. The similar patterns of activity observed for imagined and real performance suggest that imagination tasks may be useful for training inhibitory processes. Nevertheless, brain activation was generally weaker during mental rehearsal, probably as a result of the reduced engagement of top-down mechanisms and limited error processing.

  17. Stopping, goal-conflict, trait anxiety and frontal rhythmic power in the stop-signal task.

    Science.gov (United States)

    Neo, Phoebe S-H; Thurlow, Jane K; McNaughton, Neil

    2011-12-01

    The medial right frontal cortex is implicated in fast stopping of an initiated motor action in the stop-signal task (SST). To assess whether this region is also involved in the slower behavioural inhibition induced by goal conflict, we tested for effects of goal conflict (when stop and go tendencies are balanced) on low-frequency rhythms in the SST. Stop trials were divided, according to the delays at which the stop signal occurred, into short-, intermediate-, and long-delay trials. Consistent with goal-conflict processing, intermediate-delay trials were associated with greater 7-8 Hz EEG power than short- or long-delay trials at medial right frontal sites (Fz, F4, and F8). At F8, 7-8 Hz power was linked to high trait anxiety and neuroticism. A separate 4-7 Hz power increase was also seen in stop, relative to go, trials, but this was independent of delay, was maximal at the central midline site Cz, and predicted faster stopping. Together with previous data on the SST, these results suggest that the right frontal region could be involved in multiple inhibition mechanisms. We propose a hierarchical model of the control of stopping that integrates the literature on the neural control of fast motor stopping with that on slower, motive-directed behavioural inhibition.

  18. Periodic solutions of a multi-DOF beam system with impact

    NARCIS (Netherlands)

    Vorst, E.L.B. van de; Campen, D.H. van; Kraker, A. de; Fey, R.H.B

    1996-01-01

    The steady state behaviour is analyzed of a periodically driven multi-DOF beam system which has an elastic stop at its middle. The elastic stop is modelled in a continuous way by using the contact law of Hertz. The beam is modelled by using finite elements and subsequently reduced by using a compone

  19. Design, construction and cooling system performance of a prototype cryogenic stopping cell for the Super-FRS at FAIR

    Energy Technology Data Exchange (ETDEWEB)

    Ranjan, M. [KVI-Center for Advanced Radiation Technology, University of Groningen - Zernikelaan 25, 9747 AA Groningen (Netherlands); Dendooven, P., E-mail: p.g.dendooven@rug.nl [KVI-Center for Advanced Radiation Technology, University of Groningen - Zernikelaan 25, 9747 AA Groningen (Netherlands); Purushothaman, S. [GSI Helmholtz Centre for Heavy Ion Research - Planckstraße 1, 64291 Darmstadt (Germany); Dickel, T. [GSI Helmholtz Centre for Heavy Ion Research - Planckstraße 1, 64291 Darmstadt (Germany); II. Physikalisches Institut, Justus-Liebig-Universität Gießen - Heinrich-Buff-Ring 16, 35392 Gießen (Germany); Reiter, M.P. [II. Physikalisches Institut, Justus-Liebig-Universität Gießen - Heinrich-Buff-Ring 16, 35392 Gießen (Germany); Ayet, S. [GSI Helmholtz Centre for Heavy Ion Research - Planckstraße 1, 64291 Darmstadt (Germany); Haettner, E. [GSI Helmholtz Centre for Heavy Ion Research - Planckstraße 1, 64291 Darmstadt (Germany); II. Physikalisches Institut, Justus-Liebig-Universität Gießen - Heinrich-Buff-Ring 16, 35392 Gießen (Germany); Moore, I.D. [University of Jyväskylä - FI-40014, Jyväskylä (Finland); Kalantar-Nayestanaki, N. [KVI-Center for Advanced Radiation Technology, University of Groningen - Zernikelaan 25, 9747 AA Groningen (Netherlands); and others

    2015-01-11

    A cryogenic stopping cell for stopping energetic radioactive ions and extracting them as a low energy beam was developed. This first ever cryogenically operated stopping cell serves as prototype device for the Low-Energy Branch of the Super-FRS at FAIR. The cell has a stopping volume that is 1 m long and 25 cm in diameter. Ions are guided by a DC field along the length of the stopping cell and by a combined RF and DC fields provided by an RF carpet at the exit-hole side. The ultra-high purity of the stopping gas required for optimum ion survival is reached by cryogenic operation. The design considerations and construction of the cryogenic stopping cell, as well as some performance characteristics, are described in detail. Special attention is given to the cryogenic aspects in the design and construction of the stopping cell and the cryocooler-based cooling system. The cooling system allows the operation of the stopping cell at any desired temperature between about 70 K and room temperature. The cooling system performance in realistic on-line conditions at the FRS Ion Catcher Facility at GSI is discussed. A temperature of 110 K at which efficient ion survival was observed is obtained after 10 h of cooling. A minimum temperature of the stopping gas of 72 K was reached. The expertise gained from the design, construction and performance of the prototype cryogenic stopping cell has allowed the development of a final version for the Low-Energy Branch of the Super-FRS to proceed.

  20. Determination of the antiproton-to-electron mass ratio by precision laser spectroscopy of $\\overline{p}He^{+}$

    CERN Document Server

    Hori, M; Eades, John; Gomikawa, K; Hayano, R S; Ono, N; Pirkl, Werner; Widmann, E; Torii, H A; Juhász, B; Barna, D; Horváth, D

    2006-01-01

    A femtosecond optical frequency comb and continuous-wave pulse- amplified laser were used to measure 12 transition frequencies of antiprotonic helium to fractional precisions of (9-16) 10/sup -9lifetimes hitherto unaccessible to our precision laser spectroscopy method. Comparisons with three-body QED calculations yielded an antiproton-to-electron mass ratio of M/sub pmacron//m/sub e/=1836.152 674(5).

  1. Measuring lifetimes of long-lived charged massive particles stopped in LHC detectors.

    Science.gov (United States)

    Asai, Shoji; Hamaguchi, Koichi; Shirai, Satoshi

    2009-10-02

    Long-lived charged massive particles (CHAMPs) appear in various particle physics models beyond the standard model. In this Letter, we discuss the prospects for studying the stopping and decaying events of such long-lived CHAMPs at the LHC detectors, and show that the lifetime measurement (and the study of decay products) is possible with the LHC detectors for a wide range of the lifetime O(0.1)-O(10(10)) sec, by using periods of no pp collision. Even a short lifetime of order 1 sec can be measured by (i) identifying the stopping event with the on-line event filter, (ii) immediately making a beam-dump signal which stops the pp collision of the LHC, and at the same time (iii) changing the trigger menu to optimize it for the detection of a CHAMP decay in the calorimeter. Other possibilities are also discussed.

  2. Hybrid stop schedule of urban rail train

    Directory of Open Access Journals (Sweden)

    Zhengmin Tan

    2015-01-01

    Full Text Available Purpose: In order to better serve the transport demand of urban area by rail, target at the Ur-ban Rail Train Stop Schedule problem.Design/methodology/approach: Bi-level mathematical programming model and game relation was used.Findings: A 0-1 bi-level mathematical programming model for urban rail transit hybrid Stop Schedule is developed when game relation between train Stop Schedule and passenger transfer choice is considered.Research limitations/implications: The research is still in progress. Practical implications: ChongQing urban rail line 2 was taken as an example, the practical application of the model has proved its feasibility and efficiency.Originality/value: A 0-1 bi-level mathematical programming model for urban rail transit hybrid Stop Schedule is developed. The upper level model is Stop Schedule targeting at the optimal profit from the operators side. The lower level model is passenger routing aims to minimize total travel time. According to its features, the bi-level model is integrated in order to be directly solvable by optimizing software.

  3. Collective Deceleration: Toward a Compact Beam Dump

    Energy Technology Data Exchange (ETDEWEB)

    Wu, H.-C.; /Munich, Max Planck Inst. Quantenopt.; Tajima, T.; Habs, D.; /Munich, Max Planck Inst. Quantenopt. /Munich U.; Chao, A.W.; /SLAC; Meyer-ter-Vehn, J.; /Munich, Max Planck Inst. Quantenopt.

    2011-11-28

    With the increasing development of laser accelerators, the electron energy is already beyond GeV and even higher in near future. Conventional beam dump based on ionization or radiation loss mechanism is cumbersome and costly, also has radiological hazards. We revisit the stopping power of high-energy charged particles in matter and discuss the associated problem of beam dump from the point of view of collective deceleration. The collective stopping length in an ionized gas can be several orders of magnitude shorter than the Bethe-Bloch and multiple electromagnetic cascades stopping length in solid. At the mean time, the tenuous density of the gas makes the radioactivation negligible. Such a compact and non-radioactivating beam dump works well for short and dense bunches, which is typically generated from laser wakefield accelerator.

  4. Search for charm in pion and anti-proton interactions near threshold. [8. 5 to 15. 0, cross sections, branching ratios

    Energy Technology Data Exchange (ETDEWEB)

    Kadel, R W

    1977-08-01

    A search is reported for charmed particles produced by antiprotons of momentum 15.0, 12.4, and 8.5 GeV/c and pions of momentum 15.0 and 10.5 GeV/c. Charged particles emerging from a carbon target near 90/sup 0/ in the center of mass (18/sup 0/ lab) were detected in a double arm spectrometer with a low momentum cutoff of P/sub lab/ greater than or equal to 1 GeV/c. The best upper limit is the process anti PN ..-->.. D/sup 0/( anti D/sup 0/) + X, where the D/sup 0/ (anti D/sup 0/) decays into K/sup -/ - ..pi../sup +/ (K/sup +/ - ..pi../sup -/), is: sigmaB = 780 +- 300 nb at a beam momentum of 8.5 GeV/c. For the 10.5 GeV/c pion running the trigger was restricted by requiring the presence of a slow forward pion in a third spectrometer area, in coincidence with the usual double arm trigger. The acceptance of the third arm was chosen to include pions from the decay of the charmed D*/sup -/ meson, which has a very small Q value. The upper limit for the process: ..pi../sup -/N ..-->.. D*/sup -/ + X, D*/sup -/ ..-->.. ..pi../sup -/ + anti D/sup 0/, anti D/sup 0/ ..-->.. K/sup +/ + ..pi../sup -/ is sigmaB = 16 +- 16 nb. Additionally, a measurement of inclusive K* (1421) production in anti-proton interactions at 8.5 GeV/c is reported. The cross-section times branching ratio is: sigma(anti PN ..-->.. K*(1421) + X)*B/sub K*..-->..K..pi../ = 4. +- .8 x 10/sup -29/ cm/sup 2/. (JFP)

  5. The Origination and Diagnostics of Uncaptured Beam in the Tevatron and Its Control by Electron Lenses

    CERN Document Server

    Zhang, Xiao-Long; Kamerdzhiev, Vsevolod; Lebedev, Valery; Shiltsev, Vladimir; Thurman-Keup, Randy; Tollestrup, Alvin V

    2008-01-01

    In the Collider Run II, the Tevatron operates with 36 high intensity bunches of 980 GeV protons and antiprotons. Particles not captured by the Tevatron RF system pose a threat to quench the superconducting magnet during acceleration or at beam abort. We describe the main mechanisms for the origination of this uncaptured beam, and present measurements of its main parameters by means of a newly developed diagnostics system. The Tevatron Electron Lens is effectively used in the Collider Run II operation to remove uncaptured beam and keep its intensity in the abort gaps at a safe level.

  6. Generation and diagnostics of uncaptured beam in the Fermilab Tevatron and its control by electron lenses

    Science.gov (United States)

    Zhang, Xiao-Long; Bishofberger, Kip; Kamerdzhiev, Vsevolod; Lebedev, Valery; Shiltsev, Vladimir; Thurman-Keup, Randy; Tollestrup, Alvin

    2008-05-01

    In the collider run II, the Tevatron operates with 36 high intensity bunches of 980 GeV protons and antiprotons. Particles not captured by the Tevatron rf system pose a threat since they can quench the superconducting magnets during acceleration or at beam abort. We describe the main mechanisms for the origination of this uncaptured beam, and present measurements of its main parameters by means of a newly developed diagnostics system. The Tevatron electron lens is effectively used in the collider run II operation to remove uncaptured beam and keep its intensity in the abort gaps at a safe level.

  7. Impact of Impulse Stops on Pedestrian Flow

    CERN Document Server

    Kwak, Jaeyoung; Luttinen, Tapio; Kosonen, Iisakki

    2015-01-01

    We numerically study the impact of impulse stops on pedestrian flow for a straight corridor with multiple attractions. The impulse stop is simulated by the switching behavior model, a function of the social influence strength and the number of attendees near the attraction. When the pedestrian influx is low, one can observe a stable flow where attendees make a complete stop at an attraction and then leave the attraction after a certain amount of time. When the pedestrian influx is high, an unstable flow is observed for strong social influence. In the unstable flow, attendees near the attraction are crowded out from the clusters by others due to the interpersonal repulsion. The expelled pedestrians impede the pedestrian traffic between the left and right boundaries of the corridor. These collective patterns of pedestrian flow are summarized in a schematic phase diagram.

  8. Molecular dynamics simulations of classical stopping power.

    Science.gov (United States)

    Grabowski, Paul E; Surh, Michael P; Richards, David F; Graziani, Frank R; Murillo, Michael S

    2013-11-22

    Molecular dynamics can provide very accurate tests of classical kinetic theory; for example, unambiguous comparisons can be made for classical particles interacting via a repulsive 1/r potential. The plasma stopping power problem, of great interest in its own right, provides an especially stringent test of a velocity-dependent transport property. We have performed large-scale (~10(4)-10(6) particles) molecular dynamics simulations of charged-particle stopping in a classical electron gas that span the weak to moderately strong intratarget coupling regimes. Projectile-target coupling is varied with projectile charge and velocity. Comparisons are made with disparate kinetic theories (both Boltzmann and Lenard-Balescu classes) and fully convergent theories to establish regimes of validity. We extend these various stopping models to improve agreement with the MD data and provide a useful fit to our results.

  9. The Extent of the Stop Coannihilation Strip

    CERN Document Server

    Ellis, John; Zheng, Jiaming

    2014-01-01

    Many supersymmetric models such as the CMSSM feature a strip in parameter space where the lightest neutralino \\chi is identified as the lightest supersymmetric particle (LSP), the lighter stop squark \\tilde t_1 is the next-to-lightest supersymmetric particle (NLSP), and the relic \\chi cold dark matter density is brought into the range allowed by astrophysics and cosmology by coannihilation with the lighter stop squark \\tilde t_1 NLSP. We calculate the stop coannihilation strip in the CMSSM, incorporating Sommerfeld enhancement effects, and explore the relevant phenomenological constraints and phenomenological signatures. In particular, we show that the \\tilde t_1 may weigh several TeV, and its lifetime may be in the nanosecond range, features that are more general than the specific CMSSM scenarios that we study in this paper.

  10. New stopping criteria for segmenting DNA sequences

    CERN Document Server

    Li, W

    2001-01-01

    We propose a solution on the stopping criterion in segmenting inhomogeneous DNA sequences with complex statistical patterns. This new stopping criterion is based on Bayesian Information Criterion (BIC) in the model selection framework. When this stopping criterion is applied to a left telomere sequence of yeast Saccharomyces cerevisiae and the complete genome sequence of bacterium Escherichia coli, borders of biologically meaningful units were identified (e.g. subtelomeric units, replication origin, and replication terminus), and a more reasonable number of domains was obtained. We also introduce a measure called segmentation strength which can be used to control the delineation of large domains. The relationship between the average domain size and the threshold of segmentation strength is determined for several genome sequences.

  11. StopWatcher: A Mobile Application to Improve Stop Sign Awareness for Driving Safety

    Directory of Open Access Journals (Sweden)

    Carl Tucker

    2012-01-01

    Full Text Available Stop signs are the primary form of traffic control in the United States. However, they have a tendency to be much less effective than other forms of traffic control like traffic lights. This is due to their smaller size, lack of lighting, and the fact that they may become visually obscured from the road. In this paper, we offer a solution to this problem in the form of a mobile application implemented in the Android platform: StopWatcher. It is designed to alert a driver when they are approaching a stop sign using a voice notification system (VNS. A field test was performed in a snowy environment. The test results demonstrate that the application can detect all of the stop signs correctly, even when some of them were obstructed by the snow, which in turn greatly improves the user awareness of stop signs.

  12. Antihyperon potentials in nuclei via exclusive antiproton-nucleus reactions at FAIR

    CERN Document Server

    Lorente, Alicia Sanchez; Steinen, Marcell; Pochodzalla, Josef

    2015-01-01

    The exclusive production of hyperon-antihyperon pairs close to their production threshold in antiproton - nucleus collisions offers a unique and hitherto unexplored opportunity to elucidate the behaviour of antihyperons in nuclei. For the first time we analyse these reactions in a microscopic transport model using the the Gie\\ss en Boltzmann-Uehling-Uhlenbeck transport model. The calculation take the delicate interplay between the strong absorption of antihyperons, their rescattering and refraction at the nuclear surface as well as the Fermi motion of the struck nucleon into account. We find a substantial sensitivity of transverse momentum correlations of coincident $\\Lambda\\overline{\\Lambda}$-pairs to the assumed depth of the $\\overline{\\Lambda}$-potential. Because of the high cross section for this process and the simplicity of the experimental method our results are highly relevant for future activities at the international Facility for Antiproton and Ion Research (FAIR).

  13. Antiproton-proton Annihilation Into Two Mesons: The Role Of Relativistic Distortion

    CERN Document Server

    El-Bennich, B O

    2004-01-01

    The more than a decade old data on differential cross sections and analyzing powers in antiproton-proton annihilation into two pions (or two kaons), measured at the Low Energy Antiproton Ring (LEAR) of CERN, have stimulated several theoretical investigations. A characteristic feature of the data are the large variations of the scattering observables as a function of the scattering angle and of the laboratory energy already below 100 MeV. Amplitude analyzes reproduce the data with few partial waves (J ≤ 4) and one concludes that the annihilation process is very short- ranged and of the order of the nucleon size. Nonetheless, early models, using either baryonic or quark degrees of freedom, give rise to an even shorter antibaryon-baryon interaction failing to produce substantial higher (J ≥ 2) partial wave amplitudes and consequently to adequately describe the LEAR data. In this thesis, we systematically consider improvements within the framework of quark-line diagrams. We first derive various quar...

  14. Further studies of double ionization of He, Ne, and Ar by fast and slow antiprotons

    Science.gov (United States)

    Andersen, L. H.; Hvelplund, P.; Knudsen, H.; Møller, S. P.; Pedersen, J. O. P.; Tang-Petersen, S.; Uggerhøj, E.; Elsener, K.; Morenzoni, E.

    1989-12-01

    Measurements of the ratio R between double- and single-ionization cross sections for antiproton impact on He, Ne, and Ar targets are reported for impact energies ranging from 65 keV to 20 MeV. At high energies the results are found to merge with proton results at around 20 MeV, and the high-energy limit of the common ratio is in good agreement with recent first-Born-calculation results for the helium target. The large difference previously observed in the ratio R for protons and antiprotons at energies between 0.5 and 5 MeV is found to persist down to the lowest energies investigated here.

  15. Further studies of double ionization of He, Ne, and Ar by fast and slow antiprotons

    Energy Technology Data Exchange (ETDEWEB)

    Andersen, L.H.; Hvelplund, P.; Knudsen, H.; Moller, S.P.; Pedersen, J.O.P.; Tang-Petersen, S.; Uggerhoj, E. (Institute of Physics, University of Aarhus, DK-8000 Aarhus C, Denmark (Denmark)); Elsener, K. (CERN, CH-1211 Geneva 23, (Switzerland)); Morenzoni, E. (PSI, CH-5234 Villigen, (Switzerland))

    1989-12-15

    Measurements of the ratio {ital R} between double- and single-ionization cross sections for antiproton impact on He, Ne, and Ar targets are reported for impact energies ranging from 65 keV to 20 MeV. At high energies the results are found to merge with proton results at around 20 MeV, and the high-energy limit of the common ratio is in good agreement with recent first-Born-calculation results for the helium target. The large difference previously observed in the ratio {ital R} for protons and antiprotons at energies between 0.5 and 5 MeV is found to persist down to the lowest energies investigated here.

  16. 10 GeV dark matter candidates and cosmic-ray antiprotons

    CERN Document Server

    Lavalle, Julien

    2010-01-01

    Recent measurements performed with some direct dark matter detection experiments, e.g. CDMS-II and CoGENT (after DAMA/LIBRA), have unveiled a few events compatible with WIMP-nuclei interactions. The preferred mass range is around 10 GeV, with a quite large spin-independent cross section of $10^{-43}-10^{-41}\\,{\\rm cm^2}$. In this letter, we recall that a light WIMP with dominant couplings to quarks should also generate cosmic-ray antiprotons. Taking advantage of recent works constraining the Galactic dark matter mass profile on the one hand and on cosmic-ray propagation on the other hand, we point out that considering a thermal annihilation cross section for such low mass candidates unavoidably results in an antiproton flux in tension with the current data, leading either to exclusion or to observable features. This should be taken into account for a consistent interpretation of direct detection signals.

  17. First experimental detection of antiproton in-flight annihilation on nuclei at 130 keV

    CERN Document Server

    Aghai-Khozani, H; Corradini, M; Hayano, R; Hori, M; Kobayashi, T; Leali, M; Lodi-Rizzini, E; Mascagna, V; Prest, M; Soter, A; Todoroki, K; Vallazza, E; Venturelli, L; Zurlo, N

    2012-01-01

    The existing data of antinucleon-nucleon and antinucleon-nuclei annihilation cross-sections are confined to energies above about 1MeV. Experimental limitations have prevented till now the lower energies data to be achieved in spite of the interest they represent for theoretical models. One of the unresolved question concerns the antiproton annihilation cross-section measured at LEAR on light nuclei in the MeV region, which show a saturation with the mass number of the target nucleus against any naive expectation. With regard to fundamental cosmology, the knowledge of the annihilation cross-sections at energies below 1MeV can contribute to understand the matter-antimatter asymmetry in the Universe. We present here the experimental demonstration of the feasibility of the measurement of antiproton-nuclei annihilation cross-sections in the 100 keV region.

  18. Spectral Intensities of Antiprotons and the lifetime of Cosmic Rays in the Galaxy

    CERN Document Server

    Cowsik, Ramanath

    2015-01-01

    In this paper we note that the spectral intensities of antiprotons observed in Galactic cosmic rays in the energy range ~ 1-100 GeV by BESS, PAMELA and AMS instruments display nearly the same spectral shape as that generated by primary cosmic rays through their interaction with matter in the interstellar medium, without any significant modifications. More importantly, a constant residence time of ~ 2.5 +/-0.7 million years in the Galactic volume, independent of the energy of cosmic rays, matches the observed intensities. A small additional component of secondary antiprotons in the energy below 10 GeV, generated in cocoon-like regions surrounding the cosmic-ray sources, seems to be present. We discuss this result in the context of observations of other secondary components like positrons and Boron, and conclude with general remarks about the origins and propagation of cosmic rays.

  19. Synchrotron radiation based beam diagnostics at the Fermilab Tevatron

    CERN Document Server

    Thurman-Keup, R; Hahn, A; Hurh, P; Lorman, E; Lundberg, C; Meyer, T; Miller, D; Pordes, S; Valishev, A

    2011-01-01

    Synchrotron radiation has been used for many years as a beam diagnostic at electron accelerators. It is not normally associated with proton accelerators as the intensity of the radiation is too weak to make detection practical. However, if one utilizes the radiation originating near the edge of a bending magnet, or from a short magnet, the rapidly changing magnetic field serves to enhance the wavelengths shorter than the cutoff wavelength, which for more recent high energy proton accelerators such as Fermilab's Tevatron, tends to be visible light. This paper discusses the implementation at the Tevatron of two devices. A transverse beam profile monitor images the synchrotron radiation coming from the proton and antiproton beams separately and provides profile data for each bunch. A second monitor measures the low-level intensity of beam in the abort gaps which poses a danger to both the accelerator's superconducting magnets and the silicon detectors of the high energy physics experiments. Comparisons of measur...

  20. Probing Matter Radii of Neutron-Rich Nuclei by Antiproton Scattering

    OpenAIRE

    Lenske, H.; P. Kienle

    2005-01-01

    We propose to use antiprotons to investigate the sizes of stable and neutron-rich exotic nuclei by measurements of the $\\pbar A$ absorption cross section along isotopic chains in inverse kinematics. The expected effects are studied theoretically in a microscopic model. The $\\pbar U$ optical potentials are obtained by folding free space $\\pbar N$ scattering amplitudes with HFB ground state densities and solving the scattering equations by direct integration. The mass dependence of absorption c...

  1. Proceedings of the Antiproton Technology Workshop Held in Upton, New York on 10 May 1989

    Science.gov (United States)

    1989-05-01

    Edwards Air Force Base, California 93523-5000 mm~mmmmmmmml mmIl.• ml l iJ m NOTICE When U.S. Government drawings, specifications, or other data are...before at these meetings, ASTER, named after the wildflower . Since I am limited to about ten minutes, I will keep my talk simple. Here is the outline...CALLAS JET PROPULSION LABORATORY CALIFORNIA INSTITUTE OF TECHNOLOGY PASADENA, CA PRESENTED AT THE ANTIPROTON TECHNOLOGY WORKSHOP HELD AT BROOKHAVEN

  2. Slope analysis for elastic proton-proton and proton-antiproton scattering

    OpenAIRE

    Okorokov, V. A.

    2008-01-01

    The diffraction slope parameter is investigated for elastic proton-proton and proton-antiproton scattering based on the all available experimental data at intermediate square of momentum transfer in the main. Energy dependence of the elastic diffraction slope is approximated by various analytic functions in a model-independent fashion. The expanded standard logarithmic approximations allow to describe experimental slopes in all available energy range at qualitative level reasonably. Various f...

  3. Stop consonant discrimination based on human audition.

    Science.gov (United States)

    Searle, C L; Jacobson, J Z; Rayment, S G

    1979-03-01

    A system for discrimination of stop consonants has been designed on the basis of studies of auditory physiology and psychophysics. The system consists of a one-third octave filter bank as an approximation to auditory tuning curves, a bank of high speed, wide dynamic range envelope detectors, a logarithmic amplifier, and a digital computer for analysis and display. Features, chosen on the basis of psychophysical experiments, are then abstracted, and fed to a discriminant analysis program which decides on the most probable phomene. Discrimination accuracy of about 77% for stop consonants in initial position has been achieved, with a 15-speaker data set.

  4. A Second Generation Radioactive Nuclear Beam Facility at CERN

    CERN Document Server

    Äystö, J; Lindroos, M; Ravn, H L; Van Duppen, P

    2000-01-01

    The proposed Superconducting Proton Linac (SPL) at CERN would be an ideal driver for a proton-driven second-generation Radioactive Nuclear Beam facility. We propose to investigate the feasibility of constructing such a facility at CERN close to the present PS Booster ISOLDE facility. The existing ISOLDE facility would be fed with a 10 micro-amps proton beam from SPL, providing the physics community with a low-intensity experimental area. A second, new facility would be built with target stations deep underground, permitting proton beam intensities of more than 100 micro-amps. The secondary beams can be post-accelerated to 20-100 MeV/u and there will be a storage ring complex and large segmented detectors in the experimental area. Also, benefits from a muon-ion collider or from merging the ions and muons should be investigated. Since the antiproton decelerator would be nearby, the opportunities for antiprotonic radioactive atom studies should be pursued as well.

  5. Bayesian analysis of spatial-dependent cosmic-ray propagation: Astrophysical background of antiprotons and positrons

    Science.gov (United States)

    Feng, Jie; Tomassetti, Nicola; Oliva, Alberto

    2016-12-01

    The AMS-02 experiment has reported a new measurement of the antiproton/proton ratio in Galactic cosmic rays (CRs). In the energy range E ˜60 - 450 GeV , this ratio is found to be remarkably constant. Using recent data on CR proton, helium, and carbon fluxes, 10Be/9Be and B/C ratios, we have performed a global Bayesian analysis based on a Markov chain Monte Carlo sampling algorithm under a "two halo model" of CR propagation. In this model, CRs are allowed to experience a different type of diffusion when they propagate in the region close to the Galactic disk. We found that the vertical extent of this region is about 900 pc above and below the disk, and the corresponding diffusion coefficient scales with energy as D ∝E0.15 , describing well the observations on primary CR spectra, secondary/primary ratios, and anisotropy. Under this model, we have carried out improved calculations of antiparticle spectra arising from secondary CR production and their corresponding uncertainties. We made use of Monte Carlo generators and accelerator data to assess the antiproton production cross sections and their uncertainties. While the positron excess requires the contribution of additional unknown sources, we found that the new AMS-02 antiproton data are consistent, within the estimated uncertainties, with our calculations based on secondary production.

  6. Measurements of Wake-Riding Electrons in Antiproton-Carbon-Foil Collisions

    CERN Multimedia

    2002-01-01

    When a charged particle passes through dielectric media, e.g. a thin carbon foil, a ``wake'' is induced. The characteristic wake-potential shows an oscillatory behaviour, with a wavelength of about $ 2 \\pi v _{p} / \\omega _{p} _{l} $ where $ v _{p} $ is the projectile velocity and $ \\omega _{p} _{l} $ the plasmon energy of the target. This induced wake potential is superimposed on the Coulomb potential of the projectile, the latter leading to a pronounced ``cusp'' of electrons leaving the solid at $ v _{e} app v _{p} $ for positively charged projectiles in the MeV region. Correspondingly, an ``anti-cusp'' is expected for antiprotons. \\\\ \\\\ In the solid, the wake-potential leads to an attractive force on electrons, and a dynamic electronic state is predicted both for proton and antiproton projectiles. In the solid, the wake-riding electrons are travelling with the projectile speed $ v _{p} $ Upon exit of the foil, the electron released from the wake-riding state of an antiproton will suddenly find itself in th...

  7. Limits on the Dark Matter from AMS-02 antiproton and positron fraction data

    CERN Document Server

    Lu, Bo-Qiang; Zong, Hong-Shi

    2015-01-01

    We derive limits on the dark matter annihilation cross section and lifetime using measurements of the AMS-02 antiproton ratio and positron fraction data. In deriving the limits, we consider the scenario of secondary particles accelerated in supernova remnants (SNRs) which has been argued to be able to reasonably account for the AMS-02 high energy positron/antiproton fraction data. We parameterize the contribution of secondary particles accelerated in SNRs and then fit the observational data within the conventional cosmic ray propagation model by adopting the GALPROP code. We use the likelihood ratio test to determine the 95$\\%$ confidence level upper limits of the possible dark matter (DM) contribution to the antiproton/positron fractions measured by AMS-02. Our limits are stronger than that set by the Fermi-LAT gamma-ray Pass 8 data of the dwarf spheroidal satellite galaxies. We also show that the solar modulation (cosmic ray propagation) parameters can play a non-negligible role in modifying the constraints...

  8. Antiproton-to-Proton Ratios for ALICE Heavy-Ion Collisions

    CERN Document Server

    Tawfik, A

    2010-01-01

    Assuming that the final state of hadronization takes place along the freezeout line, which is defined by a constant entropy density, the antiproton-to-proton ratios produced in heavy-ion collisions are studied in framework of the hadron resonance gas (HRG) model. A phase transition from quark--gluon plasma to hadrons, a hadronization, has been conjectured in order to allow modifications in the phase space volume and thus in single--particle distribution function. Implementing both modifications in the grand--canonical partition function and taking into account the experimental acceptance in heavy-ion collisions, the antiproton-to-proton ratios over center-of-mass energies $\\sqrt{s}$ ranging from AGS to RHIC are very well reproduced by the HRG model. Comparing with the same particle ratios in $pp$ collisions results in a gradually narrowing discrepancy with increasing $\\sqrt{s}$. At LHC energy, the ALICE antiproton-to-proton ratios in $pp$ collisions turn to be very well described by HRG model as well. It is l...

  9. Uniform longitudinal beam profiles in the Fermilab Recycler using adaptive rf correction

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Martin; Broemmelsiek, Daniel Robert; Chase, Brian; Crisp, James L.; Eddy, Nathan; Joireman, Paul W.; Ng, King Yuen; /Fermilab

    2007-06-01

    The Fermilab Recycler Ring is a permanent magnet based 8 GeV anti-proton storage ring. A wideband RF system, driven with ARB's (ARBitrary waveform generators), allows the system to produce programmable barrier waveforms. Beam current profile distortion was observed, its origin verified both experimentally and theoretically, and an FPGA-based correction system was designed, tested and implemented to level the bunch profile.

  10. Report on Experiment AD-4/ACE

    CERN Document Server

    Holzscheiter, M H

    2014-01-01

    After 7 years running the AD-4 Experiment at antiproton momentum of 502 MeV/c we have now assembled a complete data set and are preparing to combine all years into a single analysis of RBE vs. Depth for an antiproton beam stopping in water. We describe experimental challenges and computational issues which need to be resolved to achieve this final step.

  11. Fluent simulations for the cryogenic stopping cell for the low energy branch at FAIR

    Energy Technology Data Exchange (ETDEWEB)

    Morherr, Frank [JLU Giessen (Germany); Collaboration: FRS Ion Catcher-Collaboration

    2014-07-01

    A cryogenic stopping cell (CSC) has been developed for the low-energy branch of the Super-FRS at FAIR, GSI, Germany. The stopping cell technique is based on the stopping of in-flight separated high energetic ions in a noble gas, Helium in our case. The system design is based on the Super-FRS beam properties. By SIMION simulations the flow of the Ions in the DC-field along the stopping cell length and the ion trajectories along the DC-field of the CSC and the behavior of the RF carpet have been simulated using SIMION code in our group. Until now simulations of the gas flow are missed. Especially the design of the nozzle, where the Ions leave the stopping cell has not been investigated in detail. In the current design a straight extraction nozzle is used. With a laval-nozzle there exists a convergent solution. The goal is, to design an extraction nozzle such, that the gas flow through the nozzle becomes stable for high densities to lead the Ions. So they can be catch by the extraction RFQs. For low densities far away the gas must escape sideward so it is possible to pump it away. The gas dynamics at the extraction nozzle have been simulated using ASNYS Fluent Calculations, they will be combined with ion optics simulations, first results will be presented and allow understanding the behavior of the ions.

  12. Bystanders Are the Key to Stopping Bullying

    Science.gov (United States)

    Padgett, Sharon; Notar, Charles E.

    2013-01-01

    Bullying is the dominance over another. Bullying occurs when there is an audience. Peer bystanders provide an audience 85% of instances of bullying. If you remove the audience bullying should stop. The article is a review of literature (2002-2013) on the role of bystanders; importance of bystanders; why bystanders behave as they do; resources to…

  13. Five Reasons To Stop Saying "Good Job."

    Science.gov (United States)

    Kohn, Alfie

    2001-01-01

    Offers five reasons to stop use of positive social reinforcement, or praise, with young children. Maintains that praise manipulates children by taking advantage of their need for adult approval and exploits that dependence for adult convenience, creates "praise junkies," steals the child's pride in his or her own accomplishment, reduces interest…

  14. Car Stopping Distance on a Tabletop

    Science.gov (United States)

    Haugland, Ole Anton

    2013-01-01

    Stopping distances in car braking can be an intriguing topic in physics teaching. It illustrates some basic principles of physics, and sheds valuable light on students' attitude towards aggressive driving. Due to safety considerations, it can be difficult to make experiments with actual car braking. (Contains 2 figures.)

  15. Approximations for stop-loss reinsurance premiums

    NARCIS (Netherlands)

    Reijnen, Rajko; Albers, Willem; Kallenberg, Wilbert C.M.

    2005-01-01

    Various approximations of stop-loss reinsurance premiums are described in literature. For a wide variety of claim size distributions and retention levels, such approximations are compared in this paper to each other, as well as to a quantitative criterion. For the aggregate claims two models are use

  16. Approximations for stop-loss reinsurance premiums

    NARCIS (Netherlands)

    Reijnen, R.; Albers, W.; Kallenberg, W.C.M.

    2003-01-01

    Various approximations of stop-loss reinsurance premiums are described in literature. For a wide variety of claim size distributions and retention levels, such approximations are compared in this paper to each other, as well as to a quantitative criterion. For the aggregate claims two models are use

  17. Lifespan changes in global and selective stopping and performance adjustments

    Directory of Open Access Journals (Sweden)

    Maria Christina Van De Laar

    2011-12-01

    Full Text Available This study examined stopping and performance adjustments in four age groups (M ages: 8, 12, 21, and 76 years. All participants performed on three tasks, a standard two-choice task and the same task in which stop-signal trials were inserted requiring either the suppression of the response activated by the choice stimulus (global stop task or the suppression of the response when one stop signal was presented but not when the other stop signal occurred (selective stop task. The results showed that global stopping was faster than selective stopping in all age groups. Global stopping matured more rapidly than selective stopping. The developmental gain in stopping was considerably more pronounced compared to the loss observed during senescence. All age groups slowed the response on trials without a stop signal in the stop task compared to trials in the choice task, the elderly in particular. In addition, all age groups slowed on trials following stop-signal trials, except the elderly who did not slow following successful inhibits. By contrast, the slowing following failed inhibits was disproportionally larger in the elderly compared to young adults. Finally, sequential effects did not alter the pattern of performance adjustments. The results were interpreted in terms of developmental change in the balance between proactive and reactive control.

  18. The light stop quark with small stop-neutralino difference in the MSSM

    Energy Technology Data Exchange (ETDEWEB)

    Milstene, C.; Carena, Marcela S.; Freitas, A.; Finch, A.; Sopczak, A.; Kluge, Hannelies

    2005-12-01

    The MSSM can explain electro-weak symmetry breaking if one scalar top quark (stop) is light. In addition, in this framework, the neutralino is a good dark matter candidate and for small stop-neutralino mass differences dm{sub i} = 30 GeV, co-annihilation plays an important role to match the results from WMAP and SDSS for the relic density in the universe. In this scenario, the stops mainly decays into charm and neutralino, making its discovery difficult at hadron colliders due to background and trigger limitations. They present results for the discovery reach of the ILC for a DM candidate as low as 0(5 GeV) based on a realistic experimental simulation. Moreover, the stop parameters could be measured with high precision.

  19. A Note on the Stopping Redundancy of Linear Codes

    Institute of Scientific and Technical Information of China (English)

    Shu-Tao Xia

    2006-01-01

    In this paper, we study the stopping sets, stopping distance and stopping redundancy for binary linear codes.Stopping redundancy is a new concept proposed by Schwartz and Vardy recently for evaluating the performance of a linear code under iterative decoding over a binary erasure channel (BEC). Since the exact value of stopping redundancy is difficult to obtain in general, good lower and upper bounds are important. We obtain a new general upper bound on the stopping redundancy of binary linear codes which improves the corresponding results of Schwartz and Vardy.

  20. Stop codon reassignments in the wild.

    Science.gov (United States)

    Ivanova, Natalia N; Schwientek, Patrick; Tripp, H James; Rinke, Christian; Pati, Amrita; Huntemann, Marcel; Visel, Axel; Woyke, Tanja; Kyrpides, Nikos C; Rubin, Edward M

    2014-05-23

    The canonical genetic code is assumed to be deeply conserved across all domains of life with very few exceptions. By scanning 5.6 trillion base pairs of metagenomic data for stop codon reassignment events, we detected recoding in a substantial fraction of the >1700 environmental samples examined. We observed extensive opal and amber stop codon reassignments in bacteriophages and of opal in bacteria. Our data indicate that bacteriophages can infect hosts with a different genetic code and demonstrate phage-host antagonism based on code differences. The abundance and diversity of genetic codes present in environmental organisms should be considered in the design of engineered organisms with altered genetic codes in order to preclude the exchange of genetic information with naturally occurring species.