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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

    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...

  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. Gold fragmentation induced by stopped antiprotons

    OpenAIRE

    Lubinski, P.; Grochulska, A.; von Egidy, T.; Gulda, K.; Hartmann, F. J.; Jastrzebski, J.; Kurcewicz, W.; Pienkowski, L.; Stolarz, A.; Trzcinska, A.

    2002-01-01

    A natural gold target was irradiated with the antiproton beam from the Low Energy Antiproton Ring at CERN. Antiprotons of 200 MeV/c momentum were stopped in a thick target, products of their annihilations on Au nuclei were detected using the off-line gamma-ray spectroscopy method. In total, yields for 114 residual nuclei were determined, providing a data set to deduce the complete mass and charge distribution of all products with A > 20 from a fitting procedure. The contribution of evaporatio...

  4. Treatment Plans for Antiproton Beams

    DEFF Research Database (Denmark)

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

    Antiprotons have been proposed as potential modality for particle beam cancer therapy by Gray and Kalogeropoulos in 1985. This proposal was based on the enhancement of physical dose deposition near the end of range due to the annihilation of antiprotons when captured by a nucleus and the expectat......Antiprotons have been proposed as potential modality for particle beam cancer therapy by Gray and Kalogeropoulos in 1985. This proposal was based on the enhancement of physical dose deposition near the end of range due to the annihilation of antiprotons when captured by a nucleus and the...... expectation of an enhanced RBE of this additional dose. Starting in 2003 the AD-4 collaboration at CERN has studied biological effects of antiproton beams on V79 Chinese Hamster cells and human FaDu cells. The AD-4 collaboration has developed relative and absolute dosimetry for pulsed antiproton beams. Data...... from these measurements were used to benchmark the FLUKA Monte Carlo code, which then has been used for calculations of physical dose inside and outside of the primary antiproton beam. From clonogenic survival studies on the different cell lines mentioned above we have determined biological effective...

  5. Antiproton source beam position system

    International Nuclear Information System (INIS)

    The TeV I Beam Position Monitor (BPM) system is designed to provide a useful diagnostic tool during the commissioning and operational phases of the antiproton source. Simply stated the design goal is to provide single turn position information for intensities of > 1x109 particles, and multi-turn (clocked orbit) information for beam intensities of > 1x107 particles, both with sub-millimeter resolution. It is anticipated that the system will be used during commissioning for establishing the first turn through the Debuncher and Accumulator, for aligning injection orbits, for providing information necessary to correct closed orbits, and for measuring various machine parameters (e.g. tunes, dispersion, aperture, chromaticity). During normal antiproton operation the system will be used to monitor the beam position throughout the accumulation process

  6. A high-intensity low-momentum separated antiproton beam for the study of annihilations at rest

    CERN Document Server

    Bassompierre, G; Dalpiaz, P; Dalpiaz, P F; Ferro-Luzzi, M; Gissinger, G; Jacquey, S; Peroni, C; Schmitt, F M; Schneegans, M; Tecchio, L B

    1977-01-01

    The main features of the low-momentum separated antiproton beam built at the CERN Proton Synchrotron to allow the stopping of a large number of antiprotons are described. An effective stopping rate of 1000 antiproton per 10/sup 12/ protons on the Ps internal target is obtained. Results of the measurement of the rate of reaction pp to h /sup +/h/sup -/ in a 50 cm long liquid hydrogen target are given to illustrate the stopping and monitoring techniques. (6 refs).

  7. Polarized antiproton beam at U-70 accelerator of IHEP

    Science.gov (United States)

    Nurushev, S. B.; Chetvertkov, M. A.; Chetvertkova, V. A.; Garkusha, V. I.; Meschanin, A. P.; Mochalov, V. V.; Nurusheva, M. B.; Rykov, V. L.; Semenov, P. A.; Strikhanov, M. N.; Vasiliev, A. N.; Zapolsky, V. N.

    2016-02-01

    The polarized proton and antiproton beam channel is currently under development at the U-70 accelerator of IHEP, Protvino, Russia. An availability of the both, polarized protons and antiprotons provides an exciting opportunity for the comparative studies of spin effects induced by polarized protons and antiprotons in a variety of hadronic reactions. While the proton and antiproton beams are formed by essentially the same method, there is the specific in the antiproton beam shaping and properties compared to protons. In this report, we address some technical details of forming the polarized antiproton beam and describe its main properties.

  8. 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.

  9. CERN accelerator school: Antiprotons for colliding beam facilities

    International Nuclear Information System (INIS)

    This is a specialized course which addresses a wide spectrum of theoretical and technological problems confronting the designer of an antiproton facility for high-energy-physics research. A broad and profound basis is provided by the lecturers' substantial experience gained over many years with CERN's unique equipment. Topics include beam optics, special lattices for antiproton accumulation and storage rings, antiproton production, stochastic cooling, acceleration and storage, r.f. noise, r.f. beam manipulations, beam-beam interaction, beam stability due to ion accumulation, and diagnostics. The SPS (Super Proton Synchrotron) panti p collider, LEAR (the Low Energy Antiproton Ring at CERN), antiprotons in the ISR (Intersecting Storage Rings), the new antiproton collector (ACOL) and gas jet targets are also discussed. A table is included listing the parameters of all CERN's accelerators and storage rings. See hints under the relevant topics. (orig./HSI)

  10. 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.

  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. Transverse instability of the antiproton beam in the Recycler Ring

    CERN Document Server

    Prost, L R; Burov, A; Crisp, J; Eddy, N; Hu, M; Shemyakin, A

    2012-01-01

    The brightness of the antiproton beam in Fermilab's 8 GeV Recycler ring is limited by a transverse instability. This instability has occurred during the extraction process to the Tevatron for large stacks of antiprotons even with dampers in operation. This paper describes observed features of the instability, introduces the threshold phase density to characterize the beam stability, and finds the results to be in agreement with a resistive wall instability model. Effective exclusion of the longitudinal tails from Landau damping by decreasing the depth of the RF potential well is observed to lower the threshold density by up to a factor of two.

  13. Transverse instability of the antiproton beam in the Recycler Ring

    Energy Technology Data Exchange (ETDEWEB)

    Prost, L.R.; Bhat, C.M.; Burov, A.; Crisp, J.; Eddy, N.; Hu, M.; Shemyakin, A.; /Fermilab

    2011-03-01

    The brightness of the antiproton beam in Fermilab's 8 GeV Recycler ring is limited by a transverse instability. This instability has occurred during the extraction process to the Tevatron for large stacks of antiprotons even with dampers in operation. This paper describes observed features of the instability, introduces the threshold phase density to characterize the beam stability, and finds the results to be in agreement with a resistive wall instability model. Effective exclusion of the longitudinal tails from Landau damping by decreasing the depth of the RF potential well is observed to lower the threshold density by up to a factor of two.

  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. Proceedings of the 10 May 1989 Antiproton Technology Workshop: Addendum

    Science.gov (United States)

    Nordley, Gerald D.

    1989-09-01

    Antiprotons are particles of antimatter which release highly penetrating radiation when they are stopped in normal matter. According to presentations at the Antiproton Technology Workshop this radiation can be used, in very small quantities, to image objects and determine their composition and density. In larger amounts, the radiation could be used to kill cancer tumors or produce highly localized heating and shock waves. Titles of presentations include: Stopping Power of MeV Proton and Antiproton Beams; Recent Simulation Results of ASTER; Pbar Testing of Hydrogen Effects in Sealed Carbon-Carbon Composites; Potential for Antiprotons in Radiation Oncology; Prospects for a Commercial Antiproton Source; Prospects for Exciting Extreme States in Nuclear Matter with Intense Antiproton Beams; Status of AL Studies Relating to condensed Antimatter; Electromagnetic Traps for Atomic Antihydrogen; Antihydrogen Production; Antiproton Catalyzed Fusion; Antiproton Induced Fusion Reaction; Modeling Antiproton-Plasma Interactions; Introduction to CP Violation Studies with Pbars; and Antiproton Production Calculation by the Multistring Model VENUS.

  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

    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. Optical-data model for the stopping power of condensed matter for protons and antiprotons

    International Nuclear Information System (INIS)

    A model for the energy-loss function of a medium that is based on optical data (∼zero momentum transfer) and a quadratic extension into the momentum-transfer plane is used to evaluate the stopping power of the medium for protons and antiprotons. Energies less than ∼40 MeV are considered for which radiative energy losses and density-effect corrections are negligible. 'Higher-order' corrections to the stopping power proportional to the incident particle charge to the third power, Barkas effect, and to the fourth power, Bloch correction, are included. Calculations are presented for aluminum, carbon, copper and polystyrene. Comparisons with experimental data indicate that the optical-data model, plus higher-order corrections, provides an excellent description of energy loss for proton energies from ∼100 keV to several tens of MeV. (author)

  18. Beam Diagnostics for Measurements of Antiproton Annihilation Cross Sections at Ultra-low Energy

    Directory of Open Access Journals (Sweden)

    Todoroki K.

    2014-03-01

    Full Text Available The ASACUSA (Atomic Spectroscopy And Collisions Using Slow Antiprotons collaboration of CERN is currently attempting to measure the antiproton-nucleus in-flight annihilation cross sections on thin target foils of C, Pd, and Pt at 130 keV of kinetic energy. The low-energy antiprotons were supplied by the Antiproton Decelerator (AD and a radio-frequency quadrupole decelerator. For this measurement, a beam profile monitor based on secondary electron emission was developed. Data from this monitor was used to ensure that antiprotons were precisely tuned to the position of an 80-mm-diameter experimental target, by measuring the spatial profile of 200-ns-long beam pulses containing 105 − 106 antiprotons with an active area of 40 mm × 40 mm and a spatial resolution of 4 mm. By using this monitor, we succeeded in finely tuning antiproton beams on the target, and observed some annihilation events originating from the target.

  19. Antiprotons

    Science.gov (United States)

    Chamberlain, Owen; Segre, Emilio; Wiegand, Clyde

    1955-11-29

    Since the development of Dirac's theory of the electron and the brilliant confirmation of one of its most startling predictions by the discovery of the positron by Anderson, it has been assumed most likely that the proton would also have its charge conjugate, the antiproton. The properties that define the antiproton are: (a) charge equal to the electron charge (also in sign); (b) mass equal to the proton mass; (c) stability against spontaneous decay; (d) ability to annihilate by interaction with a proton or neutron, probably generating pions and releasing in some manner the energy 2 mc{sup 2}; (e) generation in pairs with ordinary nucleons; (f) magnetic moment equal but opposite to that of the proton; (g) fermion of spin 1/2. Not all these properties are independent, but all might ultimately be subjected to experiment.

  20. Time purified/separated antiproton beam at the AGS

    International Nuclear Information System (INIS)

    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. 10-4 at beam rates as high as 106 anti p/s. Separation by decay purification will be on the order of 1 anti p/10(π-+μ-). 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+e- and γγ 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 107 polarized muons in the beam, one has the possibility to use them for nuclear structure studies

  1. 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)

  2. Efficient accumulation of antiprotons and positrons, production of slow mono-energetic beams, and their applications

    CERN Document Server

    Yamazaki, Yasunori

    2004-01-01

    Recent progress of ASACUSA (Atomic Spectroscopy And Collisions Using Slow Antiprotons) project, particularly the antiproton trapping and slow antiproton production, is discussed. An RFQD (Radio Frequency Quadrupole Decelerator) installed in the ASACUSA beam line has an excellent deceleration efficiency of 25% providing 10-130keV antiprotons, which improves the final accumulation efficiency at least one and half orders of magnitude. The decelerated antiprotons are then injected in a large volume multiring trap, stored, and electron-cooled. About 1 million antiprotons are successfully accumulated per one AD shot and 10-500eV antiprotons are extracted as a mono-energetic beam. A UHV compatible positron accumulation is newly developed combining electron plasma and an ion cloud, which yields an accumulation rate as high as 400e **+s/mCi, two and a half orders of magnitude higher than other UHV compatible schemes. A new scheme to synthesize a spin-polarized antihydrogen beam is also discussed, which will play a vit...

  3. 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....

  4. 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)

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

    DEFF Research Database (Denmark)

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

    Purpose  Radiotherapy with antiprotons is still being investigated as a possible new beam modality. Antiprotons behave much like protons until they come to rest, where they will annihilate with a target nucleus, thereby releasing additional energy. This can potentially lead to a favourable  depth...... 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...

  6. 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.

  7. Antiproton Cancer Therapy

    DEFF Research Database (Denmark)

    Bassler, Niels

    Antiprotons are interesting as a modality in radiation therapy for the following reasons: When fast antiprotons penetrate matter, they behave as protons. Well before the Bragg-peak, protons and antiprotons have near identical stopping powers exhibit equal radiobiology. But when the antiprotons co...

  8. 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.......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....

  9. Real time imaging of stopping distributions in biological targets for antiprotons

    Energy Technology Data Exchange (ETDEWEB)

    Sellner, Stefan; Boll, Rebecca; Tegami, Sara [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

    Antiprotons are interesting particles that have special properties when used in possible cancer particle therapy. They behave almost the same as protons in the entrance channel but deposit additional annihilation energy when they come to rest in the Bragg peak region. Thus, the number of antiprotons can be reduced while still delivering the same target dose to the tumor. Healthy tissue in the entrance channel is finally less harmed compared to protons which is a ultimate goal for good cancer treatment. Additionally, annihilation energy partially goes into the creation of new particles, especially pions. They exit the body mostly non-interacting and can be detected with an external detector, enabling a real time supervision of the irradiation process. This is currently not possible in any particle treatment method. In our contribution we present model calculations for a low-cost real time detector setup and compare these to results from the recent experiment carried out with the Antiproton Cell Experiment (ACE) Collaboration at the Antiproton Decelerator (AD) at CERN as well as develop improved set-ups for future experiments.

  10. Development of fast beam-stop system using RF chopper

    International Nuclear Information System (INIS)

    To avoid heat damage and radioactivation by beam loss of the J-PARC accelerator, Machine Protection System (MPS) has been developed. Actually, high responsibility and high reliability have been achieved in J-PARC. Beam-stop method in addition to a way of RFQ OFF has been requested in order to avoid damage to the RFQ. Therefore, we have been developing a fast beam-stop system by using a RF chopper. The fast beam-stop system, including beam test, is described in this paper. (author)

  11. Proceedings of the Antiproton Technology Workshop held in Upton, New York on 10 May 1989

    Science.gov (United States)

    Nordley, Gerald D.

    1989-05-01

    Titles of presentations included: Stopping Power of MeV Proton and Antiproton Beams; Recent Simulation Results of ASTER; Pbar Testing of Hydrogen Effects in Sealed Carbon-Carbon Composites; Potential for Antiprotons in Radiation Oncology; Prospects for a Commercial Antiproton Source; Prospects for Exciting Extreme States in Nuclear Matter with Intense Antiproton Beams; Status of AL Studies Relating to Condensed Antimatter; Electromagnetic Traps for Atomic Antihydrogen; Antihydrogen Production; Headquarters DoE Antiproton Activities; Antiproton Catalyzed Fusion; Antiproton Induced Fusion Reaction; Options for a Laboratory Microfusion Facility; Modeling Antiproton-Plasma Interactions; Concepts for Experimental Determination of Radiation Shielding and Metal Clad Pellet Performance; Introduction to CP Violation Studies with Pbars; Search for CP Violation in Pbar-P to J/psi; Studies of Rare Models of Pbar-P Annihilation; and Antiproton Production Calculation by the Multistring Model VENUS Computer Code.

  12. Example of an Antiproton-Nucleon Annihilation

    Energy Technology Data Exchange (ETDEWEB)

    Chamberlain, O.; Chupp, W.W.; Ekspong, A.G.; Goldhaber, G.; Goldhaber, S.; Lofgren, E.J.; Segre, E.; Wiegand, C.; Amaldi, E.; Baroni,G.; Castagnoli, C.; Franzinetti, C.; Manfredini, A.

    1956-02-27

    The existence of antiprotons has recently been demonstrated at the Berkeley Bevatron by a counter experiment. The antiprotons were found among the momentum-analyzed (1190 Mev/c) negative particles emitted by a copper target bombarded by 6.2-Bev protons. Concurrently with the counter experiment, stacks of nuclear emulsions were exposed in the beam adjusted to 1090 Mev/c negative particles in an experiment designed to observe the properties of antiprotons when coming to rest. This required a 132 g/cm2 copper absorber to slow down the antiprotons sufficiently to stop them in the emulsion stack. Only one antiproton was found in stacks in which seven were expected, assuming a geometric interaction cross section for antiprotons in copper. It has now been found that the cross section in copper is about twice geometric, which explains this low yield.

  13. 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.

  14. Antiproton production

    International Nuclear Information System (INIS)

    The results for the antiproton momentum spectrum produced in proton reactions on lead at the CERN Antiproton Accumulator is scaled to AGS operating conditions using the Sanford-Wang formula with no correction for target material. Yield predictions as a function of momentum are shown for 28.3 GeV protons on beryllium and results are converted to antiproton beam flux. The AGS Medium Energy Separated Beam has a flux which is a factor of 2 lower than Sanford-Wang predictions. This may be due to factors affecting beam acceptance

  15. 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

    directly and indirectly exposed human fibroblasts irradiated in both plateau and Bragg peak regions of a 126 MeV antiproton beam at CERN. Cells were stained post irradiation with an anti-γ-H2AX antibody. Quantification of the γ-H2AX foci-dose relationship is consistent with a linear increase in the Bragg...... peak region. A qualitative analysis of the foci detected in the Bragg peak and plateau region indicates significant differences highlighting the different severity of DNA lesions produced along the particle path. Irradiation of desalted plasmid DNA with 5 Gy antiprotons at the Bragg peak resulted in a...

  16. Suppression of propagating TE modes in the FNAL antiproton source stochastic beam cooling system

    International Nuclear Information System (INIS)

    A method of attenuating the propagation of waveguide modes in the stochastic cooling array beam pipes to be utilized in the accumulator and debuncher rings of the Fermilab antiproton source is described. The attenuation method treated involves lining the vertical walls of the beam pipes with a ferrimagnetic material. The general solution for propagation in a nonhomogeneously loaded waveguide is presented along with numerical results specific to the antiproton source beam cooling system. Also described is a broadband, automated technique for the simultaneous measurement of complex μ and epsilon developed to aid in the characterization of different ferrite materials. Permittivity and permeability data for a typical ferrite are presented along with a discussion of the effects of these parameters on waveguide mode attenuation in the ferrite lined beam pipes

  17. Suppression of propagating TE modes in the fnal antiproton source stochastic beam cooling system

    International Nuclear Information System (INIS)

    A method of attenuating the propagation of waveguide modes in the stochastic cooling array beam pipes to be utilized in the accumulator and debuncher rings of the Fermilab antiproton source is described. The attenuation method treated involves lining the vertical walls of the beam pipes with a ferrimagnetic material. The general solution for propagation in a nonhomogeneously loaded waveguide is presented along with numerical results specific to the antiproton source beam cooling system. Also described is a broadband, automated technique for the simultaneous measurement of complex μ and epsilon developed to aid in the characterization of different ferrite materials. Permittivity and permeability data for a typical ferrite is presented along with a discussion of the effects of these parameters on waveguide mode attenuation in the ferrite lined beam pipes

  18. 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.

  19. 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...

  20. Antiproton beam parameters measurement by a new digital-receiver-based system

    CERN Document Server

    Angoletta, Maria Elena; Chohan, V; Findlay, A; Ludwig, M; Marqversen, O; Pedersen, F

    2001-01-01

    The Antiproton Decelerator (AD) provides the users with very low intensity beams, in the 107 particles range, hence prompting the development of an innovative measuring system, which was completed in early 2000. This system measures antiproton beam intensity for bunched and debunched beams, together with momentum spread and mean momentum for debunched beams. It uses a state-of-the-art Digital Receiver board, which processes data obtained from two ultra-low-noise, wide-band AC beam transformers. These have a combined bandwidth in the range 0.02 MHz - 30 MHz and are used to measure AC beam current modulation. For bunched beams, the intensity is obtained by measuring the amplitude of the fundamental and second RF Fourier components. On the magnetic plateaus the beam is debunched for stochastic or electron cooling and longitudinal beam properties (intensity, momentum spread and mean momentum) are measured by FFT-based spectral analysis of Schottky signals. The system provides real-time information characterising ...

  1. 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.

  2. AA, entrance of proton beam to antiproton production target

    CERN Multimedia

    1980-01-01

    Please look up 8010295 first. The intense proton beam from the 26 GeV PS arrives from the right, through the vacuum chamber. The big flange contains a thin window, after which the proton beam continues through free air. A beam transformer, affixed to the shielding block, measures its intensity, before it enters the hole in the concrete to hit the target behind it.

  3. Application of high quality antiproton beam to study charmonium and exotics above DD-bar threshold

    International Nuclear Information System (INIS)

    The spectroscopy of charmonium and exotic states with hidden charm is discussed. It is a good testing tool for theories of strong interactions including QCD in both perturbative and non-perturbative regime, lattice QCD, potential models and phenomenological models. An elaborated analysis of charmonium and charmed hybrid spectrum is given, and attempts to interpret recent experimental data in the above DD-bar threshold region are considered. Experiments using antiproton beam take advantage of the intensive production of particle-antiparticle pairs in antiproton-proton annihilations. Experimental data from different collaboration are analyzed with special attention given to new states with hidden charm that were discovered recently. Some of these states can be interpreted as higher-laying S, P and D wave charmonium states. But much more data on different decay modes are needed before firmer conclusions can be made. These data can be derived directly from the experiments using high quality antiproton beam with momentum up to 15 GeV/c. (authors)

  4. Status of the anti-proton production beam in the CERN PS

    International Nuclear Information System (INIS)

    A new scheme was put into operation in November 1988 to upgrade the proton beam delivered by the 26 GeV Proton Synchrotron (PS) for anti-proton production. It makes use of quasi-adiabatic manipulations of the RF parameters to squeeze a beam filling 1/2 of the PS circumference into a 1/4 turn and can in theory preserve the longitudinal emittance. A maximum intensity of 1.68 e13 ppp in 5 bunches at 26 GeV has been reached in the course of 22 weeks of operation. The limitations of the performance are analysed together with possible improvements. (author) 6 refs., 9 figs

  5. 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...... primary particles, the increased stopping power of the secondary causes an increase in the dose averaged LET. The maximum LET is recorded in the peak as 19 keV/µm. Discussion The dose-average LET in the plateau region may result in a RBE different from unity in the plateau region. RBE measurements of...

  6. 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.

  7. Simulation studies of the beam cooling process in presence of heating effects in the Extra Low ENergy Antiproton ring (ELENA)

    International Nuclear Information System (INIS)

    The Extra Low ENergy Antiproton ring (ELENA) is a small synchrotron equipped with an electron cooler, which is currently being constructed at CERN to further decelerate antiprotons from the Antiproton Decelerator (AD) from 5.3 MeV to energies as low as 100 keV. At such low energies it is very important to carefully take contributions from electron cooling and beam heating mechanisms (e.g. on the residual gas and intrabeam scattering) into account. Detailed investigations into the ion kinetics under consideration of effects from electron cooling and heating sources have been carried out, and the equilibrium phase space dimensions of the beam have been computed, based on numerical simulations using the code BETACOOL. The goal is to provide a consistent explanation of the different physical effects acting on the beam in ELENA

  8. 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.

  9. Stopping Power for Strong Beam-Plasma Coupling

    Science.gov (United States)

    Gericke, Dirk O.

    2001-10-01

    The slowing down process of charged particles in plasma targets is investigated for the case of strong beam-plasma coupling. Strong beam-plasma correlations can be considered using the collision operator of the quantum Boltzmann equation. As a first step, dynamic screening is included in the first Born approximation. This approach gives good results for moderate beam-plasma coupling (Zb Γ^3/2 Bethe-formula, the standard model of the stopping power (Bethe plus Bloch corrections and Barkas terms), the Li & Petrasso formula and simulation data (MD and PIC), is given. This comparison clearly shows the advantage of the proposed model: it smoothly interpolates between the classical low velocity regime, where strong coupling effects occur, and the high velocity quantum regime, where collective modes are important. In the latter case, the experimentally proven Bethe-formula is obtained. Furthermore, it matches the simulation data for moderate as well as strong beam-plasma coupling.

  10. 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.

  11. 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...

  12. 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...

  13. Polarization of antiprotons by antiproton decay

    International Nuclear Information System (INIS)

    The production of polarized antiproton beams at Fermilab is briefly reviewed. Two types of high-energy anti p polarimeters are described - the Coulomb-nuclear polarimeter and the Primakoff-effect polarimeter. The production of 8.9 GeV/c polarized antiprotons before entering the Fermilab accumulator ring is then discussed. 5 refs., 6 figs

  14. 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.

  15. 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.

  16. Proceedings of the 1986 summer workshop on antiproton beams in the 2-10 GeV/c range

    Energy Technology Data Exchange (ETDEWEB)

    Lazarus, D. (ed.)

    1987-05-07

    The possibilities for building a facility for the formation spectroscopy of ''charmonium'' and the study of ''exotics'' at the AGS with high intensity antiproton beams of good resolution and enhanced purity are explored. The performance potential of a number of long beams and the AGS booster are evaluated and costs are estimated. Fluxes of several 10/sup 7/ antiprotons per pulse with purities of 5% to 99% are possible with conventional long beams. A similar total antiproton flux would be available with the Booster with no beam contamination. This could effectively be enhanced by two orders of magnitude by reducing the momentum spread in order to scan very narrow (less than 1 MeV) resonances. The maximum momentum attainable with the present Booster magnet design is 5.6 GeV/c which only reaches the Chi/sub 0/ (3415) charmonium state. Modifications are possible which would raise the maximum momentum to 6.3 GeV/c to include all states up to and including eta'/sub c/ (3590) in its range. The performance potential for this physics at the AGS is found to compare favorably with that at other laboratories with more antiprotons delivered annually, running in the post-Booster era, than at FNAL or Super-Lear with ACOL under typical scheduling conditions. A high resolution purified source of antiprotons in the 2-10 GeV/c range at BNL would cost $3.0M - $4.1M including an experimental hall. There are contributed papers in the appendices.

  17. 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.

  18. 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...

  19. 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 cau...

  20. Search for Polarization Effects in the Antiproton Production Process

    International Nuclear Information System (INIS)

    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

  1. Neutrons from Antiproton Irradiation

    DEFF Research Database (Denmark)

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

    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...

  2. 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...

  3. 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^{-}...

  4. Beam-spin asymmetry of pion, kaon, proton and antiproton production in semi-inclusive deep-inelastic scattering

    International Nuclear Information System (INIS)

    Beam-spin asymmetries in the azimuthal distribution of pions, kaons, protons and antiprotons in semi-inclusive deep inelastic scattering (SIDIS) extracted from 2000-2007 HERMES data are presented. The asymmetries were measured in the kinematic region Q2>1 GeV2, W2 > 10 GeV2, 0.1 antiprotons are shown. Assuming that the SIDIS cross section factorizes to distribution (DF) and fragmentation (FF) functions that dependent on transverse quark momentum (TMD functions), one can obtain novel information about the spin-orbit correlations inside the nucleon and orbital angular momentum of quarks.

  5. Collective effects on the wakefield and stopping power of an ion beam pulse in plasmas

    International Nuclear Information System (INIS)

    A two-dimensional (2D) particle-in-cell simulation is carried out to study the collective effects on the wakefield and stopping power for a hydrogen ion beam pulse propagation in hydrogen plasmas. The dependence of collective effects on the beam velocity and density is obtained and discussed. For the beam velocity, it is found that the collective effects have the strongest impact on the wakefield as well as the stopping power in the case of the intermediate beam velocities, in which the stopping power is also the largest. For the beam density, it is found that at low beam densities, the collective contribution to the stopping power increase linearly with the increase of the beam density, which corresponds well to the results calculated using the dielectric theory. However, at high beam densities, our results show that after reaching a maximum value, the collective contribution to the stopping power starts to decrease significantly with the increase of the beam density. Besides, at high beam densities, the wakefield loses typical V-shaped cone structures, and the wavelength of the oscillation wakefield increases as the beam density increases

  6. Shielding design of electron beam stop for Dual-Axis Radiographic Hydrotest Facility (DARHT)

    International Nuclear Information System (INIS)

    An electron beam stop was designed to allow workers to be present in the experimental area while the accelerators are producing electron beam pulses. The beam stop is composed of a graphite region to stop the electron pulses and a surrounding tungsten region to attenuate photons produced by electron transport in the graphite. Radiation-transport dose calculations were performed to set the dimensions of the graphite and tungsten regions. To reduce calculational effort, electron transport in the graphite was calculated separately from photon dose transport to worker locations. The source for photon dose transport was generated by tallying photons emerging from the graphite during electron transport

  7. 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...

  8. Antiprotonic-hydrogen atoms

    International Nuclear Information System (INIS)

    Experimental studies of antiprotonic-hydrogen atoms have recently made great progress following the commissioning of the low energy antiproton facility (LEAR) at CERN in 1983. At the same time our understanding of the atomic cascade has increased considerably through measurements of the X-ray spectra. The life history of the p-bar-p atom is considered in some detail, from the initial capture of the antiproton when stopping in hydrogen, through the atomic cascade with the emission of X-rays, to the final antiproton annihilation and production of mesons. The experiments carried out at LEAR are described and the results compared with atomic cascade calculations and predictions of strong interaction effects. (author)

  9. Fabrication of Submicron Beams with Galvanic Etch Stop for Si in TMAH

    OpenAIRE

    Yuelin Wang; Heng Yang; Haitao Cheng; Rong Lu; Yanhong Wu; Xinxin Li

    2009-01-01

    A novel method has been developed to fabricate submicron beams with galvanic etch stop for Si in TMAH. The different Au:Si area ratios before and after the release of the beams are used to trigger the galvanic etch stop to fabricate submicron single crystal Si beams in standard Si wafers. Before the beams are released from the substrate, the Au electrodes are connected to the substrate electrically. The Au:Si area ratios are much smaller than the threshold value. TMAH etches the Si wafers. Af...

  10. Fabrication of Submicron Beams with Galvanic Etch Stop for Si in TMAH

    Directory of Open Access Journals (Sweden)

    Yuelin Wang

    2009-04-01

    Full Text Available A novel method has been developed to fabricate submicron beams with galvanic etch stop for Si in TMAH. The different Au:Si area ratios before and after the release of the beams are used to trigger the galvanic etch stop to fabricate submicron single crystal Si beams in standard Si wafers. Before the beams are released from the substrate, the Au electrodes are connected to the substrate electrically. The Au:Si area ratios are much smaller than the threshold value. TMAH etches the Si wafers. After the beams are fully released, they are mechanically supported by the Au wires, which also serve as the galvanic etch stop cathodes. The Au:Si area ratios are much larger than the threshold value. The beams are protected by galvanic etch stop. The thicknesses of the beams are determined by shallow dry etching before TMAH etching. A 530 nm thick beam was fabricated in standard (111 wafers. Experiments showed that the beam thicknesses did not change with over etching, even if the SiO2 layers on the surface of the beams were stripped.

  11. Theses. Beam studies for the CERN antiproton decelerator and a new interpretation of the resonance theory for betatron motion

    Energy Technology Data Exchange (ETDEWEB)

    De Ninno, G

    1999-07-01

    The two parts of the thesis are a mission-oriented task devoted to solve some practical problems of the Antiproton Decelerator (AD) project at CERN, and a theoretical study leading to a new method for representing and compensating betatron resonances. The AD is a new machine (at the moment under commissioning at CERN) that will allow the collection and the deceleration of an antiproton beam from 3.5 GeV/c down to 100 MeV/c (the momentum favoured for the foreseen physics experiments). The need to employ the AD magnets over a wide range required a careful study of their characteristics. The presence of a solenoid inside the AD electron cooling device generates linear coupling between the transverse degrees of freedom of the single-particle motion. Coupling can lead to operational problems and therefore a compensation scheme had tobe designed. The long-standing problem has been solved of how to establish a relationship between the two standard methods for dealing with linear coupling: the matrix approach and the Hamiltonian approach. The bridge was built by including in the Hamiltonian approach in the high frequency part of the perturbative Hamiltonian due to coupling. The procedure was generalised to the nonlinear case and, a new method was proposed for dealing both with linear and nonlinear resonances. (author)

  12. Theses. Beam studies for the CERN antiproton decelerator and a new interpretation of the resonance theory for betatron motion

    International Nuclear Information System (INIS)

    The two parts of the thesis are a mission-oriented task devoted to solve some practical problems of the Antiproton Decelerator (AD) project at CERN, and a theoretical study leading to a new method for representing and compensating betatron resonances. The AD is a new machine (at the moment under commissioning at CERN) that will allow the collection and the deceleration of an antiproton beam from 3.5 GeV/c down to 100 MeV/c (the momentum favoured for the foreseen physics experiments). The need to employ the AD magnets over a wide range required a careful study of their characteristics. The presence of a solenoid inside the AD electron cooling device generates linear coupling between the transverse degrees of freedom of the single-particle motion. Coupling can lead to operational problems and therefore a compensation scheme had to be designed. The long-standing problem has been solved of how to establish a relationship between the two standard methods for dealing with linear coupling: the matrix approach and the Hamiltonian approach. The bridge was built by including in the Hamiltonian approach in the high frequency part of the perturbative Hamiltonian due to coupling. The procedure was generalised to the nonlinear case and, a new method was proposed for dealing both with linear and nonlinear resonances. (author)

  13. 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.

  14. 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.

  15. An Advanced Hadron Facility: Prospects and applicability to antiproton production

    International Nuclear Information System (INIS)

    An Advanced Hadron Facility is designed to address physics problems within and beyond the Standard Model. High fluxes of secondary beams are needed for the requisite precision tests and searches for very rare decay modes of mesons and baryons. Such high fluxes at useful secondary energies are readily obtained from high intensity, intermediate energy proton beams, which are also well suited to antiproton production. If the AHF primary proton beam were merely dumped into a beam stop, it would produce on the order of 1019 to 1020 antiprotons per operating year. Current collection techniques are not likely to be capable of absorbing more than one part in 103 of this production. Thus, an AHF provides both the immediate possibility of collecting quantities of antiprotons substantially beyond those available from the LEF discussed at this meeting, and for significant increases in the available antiproton supply upon the development (at an AHF) of more efficient collection methods. The prospects are presently good for the completion of an AHF in the late 1990's

  16. Thermal buckling and natural vibration of the beam with an axial stick-slip-stop boundary

    Science.gov (United States)

    Cui, D. F.; Hu, H. Y.

    2014-04-01

    As a first attempt to study the dynamics of a heated structure with complicated boundaries, this paper deals with the thermal buckling and the natural vibration of a simply supported slender beam, which is subject to a uniformly distributed heating and has a frictional sliding end within a clearance. This sliding end is initially at a stick status under the friction force, but may be slightly slipping due to the thermal expansion of the beam until the sliding end contacts a stop, i.e., the bound of the clearance. The material properties of the beam are temperature-independent for low temperature, but temperature-dependent for high temperature. For each case, the analytic solutions for the critical buckling temperature and the natural frequencies of the heated beam are derived first. Then, discussions are made to reveal the effects of beam parameters, such as the ratio of beam length to beam thickness, the ratio of clearance to beam length and the temperature-dependent material properties, on the critical buckling temperature and the fundamental natural frequency of the heated beam. The study shows that both friction force and clearance have significant influences on the critical buckling temperature and the fundamental natural frequency of the beam. When the friction force is not very large, the clearance can greatly increase the critical buckling temperature. These conclusions enable one to properly design the stick-slip-stop boundary so as to improve the mechanical performance of the beam in thermal environments.

  17. Cancer Therapy with Antiprotons

    Science.gov (United States)

    Bassler, Niels; Holzscheiter, Michael H.; Ad-4 Collaboration

    2005-10-01

    Starting in 2003 the AD-4/ACE collaboration has studied the biological effects of antiprotons annihilating in a human tissue like material on live V-79 Chinese Hamster cells. The main goal of the work is to prove the efficacy of antiprotons for cancer therapy. In this report we discuss a critical point to be considered carefully for all particle beam radiation therapies, namely the loss of primary particles from the beam on the way to a tumor seated some distance below the surface.

  18. Nuclear physics with antiprotons

    International Nuclear Information System (INIS)

    The use of antiproton beams in Nuclear Physics has been until now limited to a few total and reaction cross section measurements and to the study of antiprotonic atoms. This situation is presently about to change with the advent of the low Energy Antiproton Ring ''LEAR'' at CERN which started to deliver antiprotons for Physics experiments in July 1983. But what can we learn from Nuclear Physics with antiprotons. To answer this question I will first review basic and simple features of the low energy antiN-N interaction and their energy dependence. I will show that the antiproton is an interesting probe to explore the nucleus and bring informations complementary to that already provided by the other usual probe like e, p, π, α particles etc... I will in turn point out a few points that make a nucleus a very useful laboratory to study the antiN-N elementary interaction and get informations that are not available in the free antiN-N interaction

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

    International Nuclear Information System (INIS)

    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  <1% when using the MA function. The impact of these range errors on clinical dose distributions is demonstrated using treatment plans for a non-small cell lung cancer patient. The change in 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. (paper)

  20. 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  impact of these range errors on clinical dose distributions is demonstrated using treatment plans for a non-small cell lung cancer patient. The change in 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.

  1. 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.

  2. 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)

  3. 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.

  4. Antiproton Star Observed in Emulsion

    Energy Technology Data Exchange (ETDEWEB)

    Chamberlain, Owen; Chupp, Warren W.; Goldhaber, Gerson; Segre,Emilio; Wiegand, Clyde; Amaldi, E.; Baroni, G.; Castagnoli, C.; Franzinetti, C.; Manfredini, A.

    1955-12-01

    In connection with the antiproton investigation at the Bevatron we planned and carried out a photographic-emulsion exposure in a magnetically selected beam of negative particles. The magnetic system was identical to the first half (one deflecting magnet and one magnetic lens) of the system used in the antiproton experiment of Chamberlain, Segre, Wiegand, and Ypsilantis. The selected particles left the copper target in the forward direction with momentum 1.09 Bev/c.

  5. Antiproton trapping in various helium media: report of the HELIUMTRAP experiment at LEAR

    International Nuclear Information System (INIS)

    HELIUMTRAP (PS205) investigates the recently discovered anomalously long-lived states of antiprotons in various helium media. An overview is given of experiments stopping antiprotons in several phases of helium performed at LEAR in the last two years. (author)

  6. Supra-thermal electron beam stopping power and guiding in dense plasmas

    International Nuclear Information System (INIS)

    Fast-electron beam stopping mechanisms in media ranging from solid to warm dense matter have been investigated experimentally and numerically. Laser driven fast electrons have been transported through solid Al targets and shock compressed Al and plastic foam targets. Their propagation has been diagnosed via rear-side optical self-emission and Kα X-rays from tracer layers. Comparison between measurements and simulations shows that the transition from collision dominated to resistive field-dominated energy loss occurs for a fast-electron current density ∼5*1011 A cm-2. The respective increases in the stopping power with target density and resistivity have been detected in each regime. Self-guided propagation over 200 μm has been observed in radially compressed targets due to ∼1 kT magnetic fields generated by resistivity gradients at the converging shock front. (authors)

  7. Ionization, stopping, and thermalization of hydrogen and boron beams injected in fusion plasmas

    Science.gov (United States)

    Lifschitz, Agustín F.; Farengo, Ricardo; Arista, Nestor R.

    2000-07-01

    The ionization, stopping, and thermalization of hydrogen and boron beams, injected, respectively, in boron and hydrogen plasmas, is studied. The evolution of the charge state populations of the neutral beams is described considering the various ionization, excitation, and charge exchange channels. The interaction of the beam with the plasma is described in terms of the Fokker-Planck equation, which is numerically solved to show in detail the evolution of the beam until final thermalization is reached. Beam energies of 640 keV/u (maximum of the cross section for the p-B11 fusion reaction) and 200 keV/u, and various plasma temperatures are considered. It is seen that, due to an important perpendicular-diffusion effect, high energy beams reach effective peak temperatures which are much higher than the plasma temperature, before equilibrium is established. The fraction of fusioned particles is also calculated. Some implications of interest for recently proposed p-B11 fusion reactor systems are drawn out.

  8. Proton stopping power measurements using high intensity short pulse lasers produced proton beams

    Energy Technology Data Exchange (ETDEWEB)

    Chen, S.N., E-mail: sophia.chen@polytechnique.edu [LULI, École Polytechnique, CNRS, CEA, UPMC, 91128 Palaiseau (France); Atzeni, S [Università di Roma “La Sapienza”, Roma (Italy); Gauthier, M.; Higginson, D.P [LULI, École Polytechnique, CNRS, CEA, UPMC, 91128 Palaiseau (France); Mangia, F. [Università di Roma “La Sapienza”, Roma (Italy); Marques, J-R; Riquier, R.; Fuchs, J. [LULI, École Polytechnique, CNRS, CEA, UPMC, 91128 Palaiseau (France)

    2014-03-11

    Proton stopping power measurements in solids and gases, typically made using proton accelerators, Van de Graf machines, etc., have existed now for many decades for many elements and compounds. We propose a new method of making this type of measurement using a different source, namely proton beams created by high intensity short pulse lasers. The advantage of this type of source is that there is the high number of particles and short bunch lengths, which is ideal for measurements of evolving mediums such as hot dense plasmas. Our measurements are consistent with exiting data and theory which validates this method.

  9. Comparison between beam-stop and beam-hole array scatter correction techniques for industrial X-ray cone-beam CT

    Energy Technology Data Exchange (ETDEWEB)

    Schoerner, K., E-mail: karsten.schoerner.ext@siemens.co [Corporate Technology, Siemens AG, 81739 Muenchen (Germany); Physik-Department, Technische Universitaet Muenchen, 85748 Garching (Germany); Goldammer, M.; Stephan, J. [Corporate Technology, Siemens AG, 81739 Muenchen (Germany)

    2011-02-01

    Research highlights: {yields} We propose a scatter correction method employing a beam-hole array. {yields} Beam-hole and beam-stop array techniques are compared in respect of geometric and scattering properties. {yields} The beam-hole array method reduces overall scattering compared to a beam-stop array. {yields} Application of the beam-hole array method is successfully demonstrated for a CT of ceramic specimen. -- Abstract: In industrial X-ray cone-beam computed tomography, the inspection of large-scale samples is important because of increasing demands on their quality and long-term mechanical resilience. Large-scale samples, for example made of aluminum or iron, are strongly scattering X-rays. Scattered radiation leads to artifacts such as cupping, streaks, and a reduction in contrast in the reconstructed CT-volume. We propose a scatter correction method based on sampling primary signals by employing a beam-hole array (BHA). In this indirect method, a scatter estimate is calculated by subtraction of the sampled primary signal from the total signal, the latter taken from an image where the BHA is absent. This technique is considered complementary to the better known beam-stop array (BSA) method. The two scatter estimation methods are compared here with respect to geometric effects, scatter-to-total ratio and practicability. Scatter estimation with the BHA method yields more accurate scatter estimates in off-centered regions, and a lower scatter-to-total ratio in critical image regions where the primary signal is very low. Scatter correction with the proposed BHA method is then applied to a ceramic specimen from power generation technologies. In the reconstructed CT volume, cupping almost completely vanishes and contrast is enhanced significantly.

  10. 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.

  11. 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.

  12. Ultra-low Energy Antiprotons at FLAIR

    OpenAIRE

    Welsch, C.; Grieser, M.; von Hahn, R; Orlov, D.; Wolf, A.; Ullrich, J.

    2004-01-01

    The Future Accelerator Facility for Beams of Ions and Antiprotons at Darmstadt will produce the highest flux of antiprotons in the world. So far it is foreseen to accelerate the antiprotons to high energies (3-15 GeV) for meson spectroscopy and other nuclear and particle physics experiments in the HESR (High Energy Storage Ring). Within the planned complex of storage rings, it is possible to decelerate the antiprotons to about 30 MeV kinetic energy, opening up the possibility to create low en...

  13. 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).

  14. The Antiproton Depth-Dose Curve in Water

    DEFF Research Database (Denmark)

    Bassler, Niels; Holzscheiter, Michael; Jäkel, Oliver; Knudsen, Helge; Kovacevic, Sandra; AD-4/ACE Collaboration

    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...

  15. 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...

  16. On the nuclear halo of a proton pencil beam stopping in water

    Science.gov (United States)

    Gottschalk, Bernard; Cascio, Ethan W.; Daartz, Juliane; Wagner, Miles S.

    2015-07-01

    The dose distribution of a proton beam stopping in water has components due to basic physics and may have others from beam contamination. We propose the concise terms core for the primary beam, halo (see Pedroni et al 2005 Phys. Med. Biol. 50 541-61) for the low dose region from charged secondaries, aura for the low dose region from neutrals, and spray for beam contamination. We have measured the dose distribution in a water tank at 177 MeV under conditions where spray, therefore radial asymmetry, is negligible. We used an ADCL calibrated thimble chamber and a Faraday cup calibrated integral beam monitor so as to obtain immediately the absolute dose per proton. We took depth scans at fixed distances from the beam centroid rather than radial scans at fixed depths. That minimizes the signal range for each scan and better reveals the structure of the core and halo. Transitions from core to halo to aura are already discernible in the raw data. The halo has components attributable to coherent and incoherent nuclear reactions. Due to elastic and inelastic scattering by the nuclear force, the Bragg peak persists to radii larger than can be accounted for by Molière single scattering. The radius of the incoherent component, a dose bump around midrange, agrees with the kinematics of knockout reactions. We have fitted the data in two ways. The first is algebraic or model dependent (MD) as far as possible, and has 25 parameters. The second, using 2D cubic spline regression, is model independent. Optimal parameterization for treatment planning will probably be a hybrid of the two, and will of course require measurements at several incident energies. The MD fit to the core term resembles that of the PSI group (Pedroni et al 2005), which has been widely emulated. However, we replace their T(w), a mass stopping power which mixes electromagnetic (EM) and nuclear effects, with one that is purely EM, arguing that protons that do not undergo hard single scatters continue to lose

  17. On the nuclear halo of a proton pencil beam stopping in water.

    Science.gov (United States)

    Gottschalk, Bernard; Cascio, Ethan W; Daartz, Juliane; Wagner, Miles S

    2015-07-21

    The dose distribution of a proton beam stopping in water has components due to basic physics and may have others from beam contamination. We propose the concise terms core for the primary beam, halo (see Pedroni et al 2005 Phys. Med. Biol. 50 541-61) for the low dose region from charged secondaries, aura for the low dose region from neutrals, and spray for beam contamination. We have measured the dose distribution in a water tank at 177 MeV under conditions where spray, therefore radial asymmetry, is negligible. We used an ADCL calibrated thimble chamber and a Faraday cup calibrated integral beam monitor so as to obtain immediately the absolute dose per proton. We took depth scans at fixed distances from the beam centroid rather than radial scans at fixed depths. That minimizes the signal range for each scan and better reveals the structure of the core and halo. Transitions from core to halo to aura are already discernible in the raw data. The halo has components attributable to coherent and incoherent nuclear reactions. Due to elastic and inelastic scattering by the nuclear force, the Bragg peak persists to radii larger than can be accounted for by Molière single scattering. The radius of the incoherent component, a dose bump around midrange, agrees with the kinematics of knockout reactions. We have fitted the data in two ways. The first is algebraic or model dependent (MD) as far as possible, and has 25 parameters. The second, using 2D cubic spline regression, is model independent. Optimal parameterization for treatment planning will probably be a hybrid of the two, and will of course require measurements at several incident energies. The MD fit to the core term resembles that of the PSI group (Pedroni et al 2005), which has been widely emulated. However, we replace their T(w), a mass stopping power which mixes electromagnetic (EM) and nuclear effects, with one that is purely EM, arguing that protons that do not undergo hard single scatters continue to lose

  18. 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

  19. The influence of magnetic fields on the wake field and stopping power of an ion-beam pulse in plasmas

    International Nuclear Information System (INIS)

    We performed two-dimensional particle-in-cell simulations to investigate how a magnetic field affects the wake field and stopping power of an ion-beam pulse moving in plasmas. The corresponding density of plasma electrons is investigated. At a weak magnetic field, the wakes exhibit typical V-shaped cone structures. As the magnetic field strengthens, the wakes spread and lose their typical V-shaped structures. At a sufficiently strong magnetic field, the wakes exhibit conversed V-shaped structures. Additionally, strengthening the magnetic field reduces the stopping power in regions of low and high beam density. However, the influence of the magnetic field becomes complicated in regions of moderate beam density. The stopping power increases in a weak magnetic field, but it decreases in a strong magnetic field. At high beam density and moderate magnetic field, two low-density channels of plasma electrons appear on both sides of the incident beam pulse trajectory. This is because electrons near the beam pulses will be attracted and move along with the beam pulses, while other electrons nearby are restricted by the magnetic field and cannot fill the gap

  20. Some prospects for antiproton physics

    International Nuclear Information System (INIS)

    Some of the possibilities for fruitful research with antiprotons are outlined below. Special emphasis is placed on the possibility of learning about quark spectroscopy and dynamics using highly precise and intense anti p beams such as LEAR. It is urged that any discussion of LAMPF II give very careful consideration to the construction of a facility competitive with LEAR

  1. 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.

  2. 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.

  3. Results of a neutrino oscillation experiment performed at a meson factory beam-stop

    International Nuclear Information System (INIS)

    This document describes a neutrino oscillation experiment performed at the Los Alamos Meson Physics Facility. The oscillation mode searched for is /bar /nu///sub μ/ → /bar /nu///sub e/. The first chapter is a review of the known properties of the neutrino and a description of the phenomenon of neutrino oscillation. Previous experimental limits on this unobserved phenomenon are also given. The second chapter describes the experimental apparatus used by the E645 experiment to detect neutrinos produced in the LAMPF beam stop. The salient features of the detector are its large mass (20 tons of CH2), its fine segmentation (to allow good particle tracking), good energy resolution, its recording of the history both before and after tracks appear in the detector, an active cosmic-ray anticoincidence shield, and 2000 gm/cm2 of passive cosmic-ray shielding. It is located 26.8 m from the neutrino source, which has a mean neutrino energy of 40 MeV. The third chapter details the reduction of the 1.3 million event data sample to a 49 event sample of neutrino candidates. Principle backgrounds are Michel electrons from stopping cosmic-ray muons and protons from np elastic scattering by cosmic-ray neutrons. The fourth chapter explains how background levels from neutrino-nuclear scattering are predicted. The result of a maximum-likelihood analysis reveals no evidence for oscillation. 90% confidence levels are set at δm2 = .10 eV2 for large mixing and sin2(2θ) = .014 for large δm2. 82 refs., 18 figs., 55 tabs

  4. Conceptual Design of an Antiproton Generation and Storage Facility

    International Nuclear Information System (INIS)

    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

  5. 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.

  6. 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.

  7. 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.

  8. 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)

  9. 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%.

  10. 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...... ever measurements of the biological effectiveness of antiprotons. Materials and methods: V79 cells were suspended in a semi-solid matrix and irradiated with 46.7 MeV antiprotons, 48 MeV protons, or 60Co c-rays. Clonogenic survival was determined as a function of depth along the particle beams. Dose and...... particle fluence response relationships were constructed from data in the plateau and Bragg peak regions of the beams and used to assess the biological effectiveness. Results: Due to uncertainties in antiproton dosimetry we defined a new term, called the biologically effective dose ratio (BEDR), which...

  11. Formation of plasmid DNA strand breaks induced by low-energy ion beam: indication of nuclear stopping effects

    International Nuclear Information System (INIS)

    Plasmid pGEM 3zf(+) was irradiated by nitrogen ion beam with energies between 20 and 100 keV and the fluence kept as 1 x 1012 ions/cm2. The irradiated plasmid was assayed by neutral electrophoresis and quantified by densitometry. The yields of DNA with single-strand and double-strand breaks first increased then decreased with increasing ion energy. There was a maximal yield value in the range of 20-100 keV. The relationship between DNA double-strand breaks (DSB) cross-section and linear energy transfer (LET) also showed a peak-shaped distribution. To understand the physical process during DNA strand breaks, a Monte Carlo calculation code known as TRIM (Transport of Ions in Matter) was used to simulate energy losses due to nuclear stopping and to electronic stopping. It can be assumed that nuclear stopping plays a more important role in DNA strand breaks than electronic stopping in this energy range. The physical mechanisms of DNA strand breaks induced by a low-energy ion beam are also discussed. (orig.)

  12. 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.

  13. Reconciling Particle-Beam and Optical Stopping-Power Measurements in Silicon

    Science.gov (United States)

    Karstens, William; Shiles, E. J.; Smith, David Y.

    A swift, charged particle passing through matter loses energy to electronic excitations via the electro-magnetic transients experienced by atoms along its path. Bethe related this process to the matter's frequency-dependent dielectric function ɛ (ℏω) through the energy-loss function, Im[-1/ ɛ (ℏω) ]. The matter's response may be summarized by a single parameter, the mean excitation energy, or I value, that combines the optical excitation spectrum and excitation probability. Formally, ln I is the mean of ln ℏω weighted by the energy-loss function. This provides an independent optical check on particle energy-loss experiments. However, a persistent disagreement is found for silicon: direct particle-beam studies yield 173.5elements suggests 165 eV. An independent determination from optical data in 1986 gave 174 eV supporting the higher values. However, recent x-ray measurements disclosed short comings in the 1986 optical data: 1. Measurements by Ershov and Lukirskii underestimated the L-edge strength, and 2. A power-law extrapolation overestimated the K-edge strength. We have updated these data and find I = 162 eV, suggesting that silicon's recommended I value should be reconsidered. While this 5% change in I value changes the stopping power by only 1%, it is significant for precision measurements with Si detectors. Supported in part by the US Department of Energy, Office of Science, Office of Nuclear Physics under Contract DE-AC02-06CH11357.

  14. 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.

  15. Antiproton fast ignition for inertial confinement fusion

    International Nuclear Information System (INIS)

    With 180 MJ/microg, antiprotons offer the highest stored energy per unit mass of any known entity. The use of antiprotons to promote fast ignition in an inertial confinement fusion (ICF) capsule and produce high target gains with only modest compression of the main fuel is investigated. Unlike standard fast ignition where the ignition energy is supplied by energetic, short pulse laser, the energy here is supplied through the ionization energy deposited when antiprotons annihilate at the center of a compressed fuel capsule. This can be considered in-situ fast ignition as it obviates the need for the external injection of the ignition energy. In the first of two candidate schemes, the antiproton package is delivered by a low-energy ion beam. In the second, autocatalytic scheme, the antiprotons are preemplaced at the center of the capsule prior to compression. In both schemes, the author estimates that ∼1012 antiprotons are required to initiate fast ignition in a typical ICF capsule and show that incorporation of a thin, heavy metal shell is desirable to enhance energy deposition within the ignitor zone. In addition to eliminating the need for a second, energetic fast laser and vulnerable final optics, this scheme would achieve central ignition without reliance on laser channeling through halo plasma or Hohlraum debris. However, in addition to the practical difficulties of storage and manipulation of antiprotons at low energy, the other large uncertainty for the practicality of such a speculative scheme is the ultimate efficiency of antiproton production in an external, optimized facility. Estimates suggest that the electrical wall plug energy per pulse required for the separate production of the antiprotons is of the same order as that required for the conventional slow compression driver

  16. Burnout experiments on the externally-finned swirl tube for steady-state and high-heat flux beam stops

    International Nuclear Information System (INIS)

    An experimental study to develop beam stops for the next generation of neutral beam injectors was started, using an ion source developed for the JT-60 neutral beam injector. A swirl tube is one of the most promising candidates for a beam stop element which can handle steady-state and high-heat flux beams. In the present experiments, a modified swirl tube, namely an externally-finned swirl tube, was tested together with a simple smooth tube, an externally finned tube, and an internally finned tube. The major dimensions of the tubes are 10 mm in outer-diameter, 1.5 mm in wall thickness, 15 mm in external fin width, and 700 mm in length. The burnout heat flux (CHF) normal to the externally finned swirl tube was 4.1±0.1 kW/cm2, where the Gaussian e-folding half-width of the beam intensity distribution was about 90 mm, the flow rate of the cooling water was 30 l/min, inlet and outlet gauge pressures were about 1 MPa and 0.2 MPa, respectively, and the temperature of the inlet water was kept to 200C during a pulse. A burnout heat flux ratio, which is defined by the ratio of the CHF value of the externally-finned swirl tube to that of the externally-finned tube, turned out to be about 1.5. Burnout heat fluxes of the tubes with a swirl tape or internal fins increase linearly with an increase of the flow rate. It was found that the tube with external fins has effects that not only reduce the thermal stress but also improve the characteristics of boiling heat transfer. (orig.)

  17. A novel capacitive accelerometer with an eight-beam-mass structure by self-stop anisotropic etching of (1 0 0) silicon

    International Nuclear Information System (INIS)

    This paper reports a novel capacitive sandwich accelerometer with an eight-beam-mass structure fabricated by self-stop anisotropic wet etching of (1 0 0) silicon and wafer-level Si–Si bonding. In this structure, eight straight beams symmetrically connect to the corners of the proof mass on both sides. These suspension beams are formed by self-stop anisotropic wet etching of (1 0 0) silicon, without heavy boron doping or Si–Si bonding. Through this beam-fabrication approach, the beam thickness can be well controlled and intrinsic stress in the beams is minimized. Accelerometers with different sensitivities can be easily fabricated by varying the thickness of the beams without making any change to the masks. For a device with 17 µm thick beams, the resonance frequency and the quality factor are 696 Hz and 47, respectively. The accelerometer has a sensitivity of 0.35 V g−1

  18. Antiprotonic helium atomcules

    Directory of Open Access Journals (Sweden)

    Sauge Sébastien

    2012-10-01

    Full Text Available About 3% of antiprotons ( stopped in helium are long-lived with microsecond lifetimes, against picoseconds in all other materials. This unusual longevity has been ascribed to the trapping of on metastable bound states in He+ helium atom-molecules thus named atomcules. Apart from their unique dual structure investigated by laser spectroscopy – a near-circular quasi-classical Rydberg atom with l ~ n – 1 ~ 37 or a special diatomic molecule with a negatively charged nucleus in high rotational state with J = l – the chemical physics aspects of their interaction with other atoms or molecules constitute an interesting topic for molecular physics. While atomcules may resist to million collisions in helium, molecular contaminants such as H2 are likely to destroy them in a single one, down to very low temperatures. In the Born-Oppenheimer framework, we interpret the molecular interaction obtained by ab initio quantum chemical calculations in terms of classical reactive channels, with activation barriers accounting for the experiments carried out in He and H2. From classical trajectory Monte Carlo simulations, we show that the thermalization stage strongly quenches initial populations, thus reduced to a recovered 3 % trapping fraction. This work illustrates the pertinence of chemical physics concepts to the study of exotic processes involving antimatter. New insights into the physico-chemistry of cold interstellar radicals are anticipated.

  19. Primary resonance of lateral vibration of a heated beam with an axial stick-slip-stop boundary

    Science.gov (United States)

    Cui, D. F.; Hu, H. Y.

    2015-03-01

    As a first endeavor, the present work deals with the primary resonance of lateral vibration of an Euler-Bernoulli beam with a sliding end and under both uniformly distributed heating and harmonic loads. The sliding end is subject to a pair of adjustable normal force and frictional force such that it is initially at a stick status, but may be slightly slipping due to the thermal expansion of the beam until it contacts a stop, i.e., the bound of the clearance. Moreover, this sliding end may also be slipping during the lateral vibration when the vibration amplitude is larger than a critical value. Firstly, based on the nonlinear relation between strain and displacement, a set of partial differential equations of the beam and the axial boundary condition for the sliding end are derived by utilizing Hamilton's principle, where both frictional force and temperature-dependent properties of material are taken into consideration. Then, Galerkin's approach is employed to simplify the partial differential equations to a set of ordinary differential equations. Subsequently, the average approach is used to determine the steady-state primary resonance. Finally, the analytical solutions are well verified through numerical simulations and the influences of system parameters, such as temperature rise and normal force, on the primary resonance of lateral vibration of the beam are discussed. The study shows that it is possible to adjust the primary resonance of lateral vibration of the heated beam with an axial stick-slip-stop boundary via the analytical solutions, which involve the normal force, the clearance and the temperature rise.

  20. Prediction of stopping-power ratios in flattening-filter free beams.

    OpenAIRE

    Ceberg, Crister; Johnsson, Stefan; Lind, Mårten; Knöös, Tommy

    2010-01-01

    PURPOSE: In recent years, there has been an increasing interest in flattening-filter free (FFF) beams. However, since the removal of the flattening filter will affect both the mean and the variance of the energy spectrum, current beam-quality specifiers may not be adequate for reference dosimetry in such beams. The purpose of this work was to investigate an alternative, more general beam-quality specifier. METHODS: The beam-quality specifier used in this work was a combination of the kerma-we...

  1. Antiprotonic Helium Atoms

    OpenAIRE

    Kartavtsev, O. I.

    1995-01-01

    Metastable antiprotonic helium atoms $^{3,4}\\! H\\! e\\bar pe$ have been discovered recently in experiments of the delayed annihilation of antiprotons in helium media. These exotic atoms survive for an enormous time (about tens of microseconds) and carry the extremely large total angular momentum $L\\sim 30-40$. The theoretical treatment of the intrinsic properties of antiprotonic helium atoms, their formation and collisions with atoms and molecules is discussed.

  2. Antiproton-proton annihilation at rest into two mesons

    International Nuclear Information System (INIS)

    Branching ratios for antiproton-proton annihilations at rest into two mesons are given. The data were obtained at LEAR by stopping antiprotons in a liquid hydrogen target. Both charged and neutral annihilation products were detected in the Crystal Barrel detector. Representative data are presented, and their bearing on the general picture of annihilation dynamics is discussed. In addition, preliminary branching ratios for two-body radiative annihilations are given. (orig.)

  3. Low-energy collisions of antiprotons with atoms and molecules

    International Nuclear Information System (INIS)

    Time-dependent close-coupling calculations were performed using the impact parameter method for antiproton and proton collisions with alkali-metal atoms and hydrogen molecules. The targets are described as effective one-electron systems using appropriate model potentials. The proton data verify the employed method while the results for antiprotons improve the literature on these systems considerably. Cross sections for ionization and excitation as well as electron-energy spectra and stopping power will be presented.

  4. From LEAR to HESR: past, present and future of meson spectroscopy with antiprotons

    International Nuclear Information System (INIS)

    Meson spectroscopy experiments performed using antiproton beams have carried out a deep and systematic study of all the main open problems of strong interaction in the non-perturbative regime. In this review, I will sketch the major achievements obtained by experiments studying antiproton annihilations at the CERN LEAR machine and at the Fermilab antiproton accumulator. Finally I will illustrate which topics might be addressed, in the next future, by the new antiproton machine (HESR) that will be available at GSI

  5. Antiproton induced DNA damage: proton like in flight, carbon-ion like near rest

    OpenAIRE

    Kavanagh, J. N.; Currell, F. J.; Timson, D.J.; Savage, K. I.; Richard, D J; S.J. McMahon(Particle Physics Department, Rutherford Appleton Laboratory, Didcot, United Kingdom); Hartley, Oliver; Cirrone, G. A. P.; Romano, F.; Prise, K M; Bassler, N.; Holzscheiter, M. H.; Schettino, G

    2013-01-01

    Biological validation of new radiotherapy modalities is essential to understand their therapeutic potential. Antiprotons have been proposed for cancer therapy due to enhanced dose deposition provided by antiproton-nucleon annihilation. We assessed cellular DNA damage and relative biological effectiveness (RBE) of a clinically relevant antiproton beam. Despite a modest LET (,19 keV/mm), antiproton spread out Bragg peak (SOBP) irradiation caused significant residual c-H2AX foci compared to X-ra...

  6. The CERN antiproton collector

    International Nuclear Information System (INIS)

    The Antiproton Collector is a new ring of much larger acceptance than the present accumulator. It is designed to receive 108 antiprotons per PS cycle. In order to be compatible with the Antiproton Accumulator, the momentum spread and the emittances are reduced from 6% to 0.2% and from 200 π mm mrad to 25 π mm mrad respectively. In addition to the ring itself, the new target area and the modifications to the stochastic systems of the Antiproton Accumulator are described. (orig.)

  7. Low energy antiproton possibilities at the AGS

    International Nuclear Information System (INIS)

    The technical feasibility of creating a pure antiproton beam at the AGS has been studied. The scheme involves an antiproton target station and transport back to the Booster synchrotron, which acts as both a purifier and accelerator/decelerator. This proposal would be very attractive to the user community since this operation could run parasitically (transparently) to the AGS operating modes. The energy range of antiprotons can be as low as 2 MeV to as high as 5 GeV. The intensity of the beam is estimated to be 7 x 107/sec above 2.5 GeV/c and 4 x 104/sec at 200 MeV/c

  8. 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 .

  9. Antiproton Radiation Therapy

    DEFF Research Database (Denmark)

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

    2007-01-01

    investigated 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...

  10. Physics with Antiprotons at PANDA

    International Nuclear Information System (INIS)

    The PANDA experiment is part of the core project of the planned Facility for Antiproton and Ion Research (FAIR) at GSI in Darmstadt (Germany)[1]. One major component of the upgraded accelerator complex is the High Energy Storage Ring (HESR) which will provide a high quality antiproton beam in the momentum range between 1.5 and 15 GeV/c. PANDA, a fixed target experiment directly implemented in the HESR, will investigate antiproton annihilations with the aim to explore fundamental questions in the cross over region of the non perturbative and the strong QCD. Due to the planned extensive physics program a multipurpose detector with a nearly complete solid angle coverage, proper particle identification over a large momentum range, and high resolution calorimetry for neutral particles is required. After an overview about the goals and the detector design of the PANDA experiment major parts of the planned physics program will be discussed, namely the meson spectroscopy and the search for exotics in the charmonium and open charm region

  11. Generation of relativistic electron beam and its anomalous stopping in the fast ignition scheme

    International Nuclear Information System (INIS)

    We present experimental/theoretical results concerning two main physics issues related to the fast ignition scheme viz. the nonlinear mechanism of conversion of incident laser energy into a relativistic electron beam at the critical layer and its subsequent transport through an overdense plasma. Theoretical/numerical modelling of the experimental data, firstly shows that the conversion of the laser energy into an inward propagating electron beam occurs through the nonlinear mechanism of wave breaking of plasma waves excited at the critical layer and, secondly the transport of the electron beam through the overdense plasma is influenced by electrostatically induced and/or turbulence induced anomalous resistivity. (author)

  12. Antiprotons at Solar Maximum

    CERN Document Server

    Bieber, J W; Engel, R; Gaisser, T K; Roesler, S; Stanev, T; Bieber, John W.; Engel, Ralph; Gaisser, Thomas K.; Roesler, Stefan; Stanev, Todor

    1999-01-01

    New measurements with good statistics will make it possible to observe the time variation of cosmic antiprotons at 1 AU through the approaching peak of solar activity. We report a new computation of the interstellar antiproton spectrum expected from collisions between cosmic protons and the interstellar gas. This spectrum is then used as input to a steady-state drift model of solar modulation, in order to provide predictions for the antiproton spectrum as well as the antiproton/proton ratio at 1 AU. Our model predicts a surprisingly large, rapid increase in the antiproton/proton ratio through the next solar maximum, followed by a large excursion in the ratio during the following decade.

  13. 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.

    2012-06-01

    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 (sw, air), with an uncertainty of 2%. The variation of (sw, 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 (sw, air) with penetration depth was observed. Since a consensus on Iw, air and Iair 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, sw,air(E), was derived from the Bethe-Bloch formula and fit to the measured data, yielding a coherent pair of Iw and Iair values with Iair/Iw = 1.157 ± 0.023. Additionally, the data from five different beam energies were combined in an average value of sw,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 sw,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.

  14. Physics with antiprotons at LEAR

    International Nuclear Information System (INIS)

    The low energy antiproton ring LEAR started to work at CERN in 1983. It provides clean anti p beams of much higher intensity and much better quality than available so far in the range from 0.1 to 2 GeV/c momentum. 16 of the 17 accepted experiments are installed and 14 of them took first data in 1983. After approx.= 240 hours of LEAR operation very first results are available. One can expect that exciting physics results be produced in many different domains provided LEAR gets enough anti p in the future. (orig.)

  15. 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

    Background. In radiation therapy, the principal dosimetric quantity of interest is the absorbed dose to water. Therefore, a dose conversion to dose to water is required for dose deposited by ion beams in other media. This is in particular necessary for dose measurements in plastic phantoms...... of magnitude is observed for SOBP. Conclusions. We conclude that for ions with small total range (zw-eq ≤3 cm) dosimetry without applying FCF could in principle be performed in phantoms of materials other than water without a significant loss of accuracy. However, in clinical high-energy ion beams...... for increased positioning accuracy, graphite calorimetry being developed as a primary standard for dose to water dosimetry, but also for the comparison of dose distributions from Monte Carlo simulations with those of pencil beam algorithms. Material and methods. In the conversion of absorbed dose to phantom...

  16. Fusion Energy and Stopping Power in a Degenerate DT Pellet Driven by a Laser-Accelerated Proton Beam

    Science.gov (United States)

    Mehrangiz, M.; Ghasemizad, A.; Jafari, S.; Khanbabaei, B.

    2016-06-01

    In this paper, we have improved the fast ignition scheme in order to have more authority needed for high-energy-gain. Due to the more penetrability and energy deposition of the particle beams in fusion targets, we employ a laser-to-ion converter foil as a scheme for generating energetic ion beams to ignite the fusion fuel. We find the favorable intensity and wavelength of incident laser by evaluating the laser-proton conversion gain. By calculating the source-target distance, proton beam power and energy are estimated. Our analysis is generalized to the plasma degeneracy effects which can increase the fusion gain several orders of magnitude by decreasing the ion-electron collisions in the plasma. It is found that the wavelength of 0.53 μm and the intensity of about 1020 W/cm2, by saving about 10% conversion coefficient, are the suitable measured values for converting a laser into protons. Besides, stopping power and fusion burn calculations have been done in degenerate and non-degenerate plasma mediums. The results indicate that in the presence of degeneracy, the rate of fusion enhances. Supported by the Research Council of University of Guilan

  17. 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...

  18. Energy and energy width measurement in the FNAL antiproton accumulator

    Energy Technology Data Exchange (ETDEWEB)

    Church, M.; Hsueh, S.; Rapidis, P.; Werkema, S.

    1991-10-01

    The Fermilab Antiproton Accumulator has recently been used to produce Charmonium resonances (charm quark, anti-charm quark bound states) in proton-antiproton annihilations using an internal H{sub 2} gas jet target. A measurement of the resonance mass and width may be obtained from a precise knowledge of the antiproton beam energy and energy spread. The beam energy is measured to an accuracy of 1 part in 10{sup 4} in the range 6.3 Gev to 4.1 Gev by measuring the orbit length and revolution frequency of the beam. The beam momentum spread is measured to an accuracy of 10% by measuring the beam frequency spread and the parameter {eta} = (P{sub beam}/F{sub rev}){center dot}(dF{sub rev}/dP{sub beam}). These two measurement techniques are described in this report.

  19. Shielding calculations for the antiproton target area

    International Nuclear Information System (INIS)

    Shielding calculations performed in conjunction with the design of the Fermilab antiproton target hall are summarized. The following radiological considerations were examined: soil activation, residual activity of components, and beam-on radiation. In addition, at the request of the designers, the energy deposition in the proposed graphite beam dump was examined for several targeting conditions in order to qualitatively determine its ability to survive

  20. 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.

  1. On the nuclear halo of a proton pencil beam stopping in water

    OpenAIRE

    Gottschalk, Bernard; Cascio, Ethan W.; Daartz, Juliane; Wagner, Miles S.

    2014-01-01

    The dose distribution of a pencil beam in water consists of a core, a halo, an aura and (possibly) spray. The core is due to primary protons which suffer multiple Coulomb scattering (MCS) and slow down by multiple collisions with atomic electrons (Bethe-Bloch theory). The halo is due to charged secondaries, many of them protons, from elastic interactions with H, elastic and inelastic interactions with O, and nonelastic interactions with O. We show that the halo radius is roughly one third of ...

  2. Unraveling resistive versus collisional contributions to relativistic electron beam stopping power in cold-solid and in warm-dense plasmas

    International Nuclear Information System (INIS)

    We present results on laser-driven relativistic electron beam propagation through aluminum samples, which are either solid and cold or compressed and heated by laser-induced shock. A full numerical description of fast electron generation and transport is found to reproduce the experimental absolute Kα yield and spot size measurements for varying target thicknesses, and to sequentially quantify the collisional and resistive electron stopping powers. The results demonstrate that both stopping mechanisms are enhanced in compressed Al samples and are attributed to the increase in the medium density and resistivity, respectively. For the achieved time- and space-averaged electronic current density, 〈jh〉∼8×1010 A/cm2 in the samples, the collisional and resistive stopping powers in warm and compressed Al are estimated to be 1.5 keV/μm and 0.8 keV/μm, respectively. By contrast, for cold and solid Al, the corresponding estimated values are 1.1 keV/μm and 0.6 keV/μm. Prospective numerical simulations involving higher jh show that the resistive stopping power can reach the same level as the collisional one. In addition to the effects of compression, the effect of the transient behavior of the resistivity of Al during relativistic electron beam transport becomes progressively more dominant, and for a significantly high current density, jh∼1012 A/cm2, cancels the difference in the electron resistive stopping power (or the total stopping power in units of areal density) between solid and compressed samples. Analytical calculations extend the analysis up to jh=1014 A/cm2 (representative of the full-scale fast ignition scenario of inertial confinement fusion), where a very rapid transition to the Spitzer resistivity regime saturates the resistive stopping power, averaged over the electron beam duration, to values of ∼1 keV/μm

  3. Construction and building of a compact RFQ spiral structure for the stopping of highly charged heavy ion beams for the HITRAP project of the GSI; Konstruktion und Aufbau einer kompakten RFQ-Spiral-Struktur zum Abbremsen hochgeladener Schwerionenstrahlen fuer das HITRAP-Projekt der GSI

    Energy Technology Data Exchange (ETDEWEB)

    Hofmann, B.

    2007-07-01

    For experiments of the atomic-physics group of the GSI in Darmstadt an ion stopper is built, which will make low-energetic, extremely highly charged ions available. The plannings for the so-called HITRAP (highly charged ion's trap) began at the beginning of the ninetieth. With this facility highly-charged heavy ions shall be stopped in two stages to very low, thermal velocities, and be available for highly precise mass spectroscopy, measurements of the g factor of the bound electron of hydrogen-like ions, and other atomic-physics experiments. This decelerator facility shall first be built in the reinjection channel behind the ESR with the possibility, to apply all components later in teh extension of the GSI in the framework of the FAIR project in the facility for low-energetic antiprotons and ions to be newly built. the present thesis treats the development and the building of an integrated RFQ debuncher stopping accelerator, which represents a part of the HITRAP stopping structures. By this the ion beam is stopped from the IH stopping accelerator with an energy of 500 keV/u to 5 keV/u. By the integrated spiral buncher the beam can be fitted in energy and energy deviation to the subsequent cooler trap. In this thesis the foundations of the particle dynamics in a RFQ accelerator for the stopping of particle beams were worked out and realized, the particle-dynamics calculations necessary for the lay-out of such a structure performed with RFQSim, suitable RF structures with the simulation program Microwave Studio developed and studied, as well as the thermal load of the structures studied with the finite-element code ALGOR. A further, central topic of this thesis is the building and the tuning of the RFQ structure in order to reach a homogeneous as possible field distribution along the electrodes. Measurements of the fields in the RFQ were performed with a disturbing condenser, at the debuncher with a disturbing body. After successfully performed vacuum tests at

  4. FAIR - the Facility for Antiproton and Ion Research: the Universe in the Lab

    Science.gov (United States)

    Weissbach, F.

    2015-11-01

    As of the year 2018 the Facility for Antiproton and Ion Research (FAIR) will offer access to exotic ion beams and beams of antiproton of unprecedented luminosity. The facility currently under construction in Darmstadt, Germany, adjacent to the existing accelerator at the GSI Helmholtz Centre for Heavy-Ion Research, will serve several collaborations and fields simultaneously: atomic, hadron, nuclear, and plasma physics.

  5. ACOL, CERN'S upgrade of the antiproton accelerator complex

    International Nuclear Information System (INIS)

    At its present best the Antiproton Accumulator (AA) produces 6 x 10/sup 9/ p-bar's/hour. In routine operation this amounts to around 10/sup 11/ p-bar's/day including anadvertent stops of all the systems involved. Post ACOL performance aims at increasing these rates tenfold

  6. Three dimensional biological dose distribution of antiprotons

    International Nuclear Information System (INIS)

    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.

  7. Interaction of antiprotons with nuclei

    Czech Academy of Sciences Publication Activity Database

    Hrtánková, Jaroslava; Mareš, Jiří

    2016-01-01

    Roč. 945, JAN (2016), s. 197-215. ISSN 0375-9474 R&D Projects: GA ČR(CZ) GA15-04301S Institutional support: RVO:61389005 Keywords : antiproton-nucleus interaction * antiproton annihilation * antiproton nuclear bound states Subject RIV: BE - Theoretical Physics Impact factor: 2.202, year: 2014

  8. 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.

  9. Inclusive production of hyperons, as well as of pions, charged kaons, protons, anti-protons and neutrons in p+p collisions at 158 GeV/c beam momentum

    International Nuclear Information System (INIS)

    New data on the production of hyperons, as well as of pions, charged kaons, protons, anti-protons, neutrons in p+p interactions are presented. The data come from a sample of 8.2 million inelastic events obtained with the NA49 detector at the CERN SPS at 158 GeV/c beam momentum. The high statistics data sample allows the extraction of detailed differential distributions as a function of xf, y and pT. The results are compared with published data and models. Moreover, the measurements provide an important reference for studying effects of cold nuclear matter in proton-nucleus and hot dense matter in nucleus-nucleus collisions. (author)

  10. Commissioning of Fermilab's Electron Cooling System for 8-GeV Antiprotons

    CERN Document Server

    Nagaitsev, Sergei; Burov, Alexey; Carlson, Kermit; Gai, Wei; Gattuso, Consolato; Hu, Martin; Kazakevich, Grigory; Kramper, Brian J; Kroc, Thomas K; Leibfritz, Jerry; Prost, Lionel; Pruss, Stanley M; Saewert, Greg W; Schmidt, Chuck; Seletsky, Sergey; Shemyakin, Alexander V; Sutherland, Mary; Tupikov, Vitali; Warner, Arden

    2005-01-01

    A 4.3-MeV electron cooling system has been installed at Fermilab in the Recycler antiproton storage ring and is being currently commissioned. The cooling system is designed to assist accumulation of 8.9-GeV/c antiprotons for the Tevatron collider operations. This paper will report on the progress of the electron beam commissioning effort as well as on detailed plans of demonstrating the cooling of antiprotons.

  11. Baryon stopping and hadronic spectra in Pb-Pb collisions at 158 GeV/nucleon

    International Nuclear Information System (INIS)

    Baryon stopping and particle production in Pb+Pb collisions at 158 GeV/nucleon are studied as a function of the collision centrality using new proton, antiproton, charged kaon and charged pion production data measured with the NA49 experiment at the CERN Super Proton Synchrotron (SPS). Stopping, which is measured by the shift in rapidity of net protons or baryons from the initial beam rapidity, increases in more central collisions. This is expected from a geometrical picture of the collisions. The stopping data are quantitatively compared to models incorporating various mechanisms for stopping. In general, microscopic transport calculations which incorporate current theoretical models of baryon stopping or use phenomenological extrapolations from simpler systems overestimate the dependence of stopping on centrality. Approximately, the yield of produced pions scales with the number of nucleons participating in the collision. A small increase in yield beyond this scaling, accompanied by a small suppression in the yield of the fastest pions, reflects the variation in stopping with centrality. Consistent with the observations from central collisions of light and heavy nuclei at the SPS, the transverse momentum distributions of all particles are observed to become harder with increasing centrality. This effect is most pronounced for the heaviest particles. This hardening is discussed in terms of multiple scattering of the incident nucleons of one colliding nucleus as they traverse the other nucleus and in terms of rescattering within the system of produced particles

  12. 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).

  13. Investigation of the antiprotonic X-ray spectrum of the lithium isotopes 6Li and 7Li

    International Nuclear Information System (INIS)

    Antiprotons of the low-energy separated anti p-beam K23 at CERN in Geneva have been stopped in thin (0.6 g/cm2) targets of the Lithium isotopes 6Li and 7Li. The characteristic X-rays of the formed antiprotonic atoms were measured with four identical high-resolution Si (Li) detectors. Three lines of the N- series, four lines of the M-series and the 3d-2p transition of the Balmer series were observed. The measured relative intensities of the M- and N-series transitions are well described by the simple cascade model of Eisenberg and Kessler. The 3d-2p transition is considerably influenced by the strong interaction between antiproton and nucleus and thus drastically reduced in intensity. The analysis of this transition yields the shift and width of the 2p level, whereas the width of the 3d level is deduced from intensity considerations. (orig./HSI)

  14. 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...

  15. Projection correlation based view interpolation for cone beam CT: primary fluence restoration in scatter measurement with a moving beam stop array

    International Nuclear Information System (INIS)

    Scatter correction is an open problem in x-ray cone beam (CB) CT. The measurement of scatter intensity with a moving beam stop array (BSA) is a promising technique that offers a low patient dose and accurate scatter measurement. However, when restoring the blocked primary fluence behind the BSA, spatial interpolation cannot well restore the high-frequency part, causing streaks in the reconstructed image. To address this problem, we deduce a projection correlation (PC) to utilize the redundancy (over-determined information) in neighbouring CB views. PC indicates that the main high-frequency information is contained in neighbouring angular projections, instead of the current projection itself, which provides a guiding principle that applies to high-frequency information restoration. On this basis, we present the projection correlation based view interpolation (PC-VI) algorithm; that it outperforms the use of only spatial interpolation is validated. The PC-VI based moving BSA method is developed. In this method, PC-VI is employed instead of spatial interpolation, and new moving modes are designed, which greatly improve the performance of the moving BSA method in terms of reliability and practicability. Evaluation is made on a high-resolution voxel-based human phantom realistically including the entire procedure of scatter measurement with a moving BSA, which is simulated by analytical ray-tracing plus Monte Carlo simulation with EGSnrc. With the proposed method, we get visually artefact-free images approaching the ideal correction. Compared with the spatial interpolation based method, the relative mean square error is reduced by a factor of 6.05-15.94 for different slices. PC-VI does well in CB redundancy mining; therefore, it has further potential in CBCT studies.

  16. Antiprotons are another matter

    International Nuclear Information System (INIS)

    Theories of gravity abound, whereas experiments in gravity are few in number. An important experiment in gravity that has not been performed is the measurement of the gravitational acceleration of antimatter. Although there have been attempts to infer these properties from those of normal matter, none of these theoretical arguments are compelling. Modern theories of gravity that attempt to unify gravity with the other forces of nature predict that in principle antimatter can fall differently than normal matter in the Earth's field. Some of these supergravity theories predict that antimatter will fall faster, and that normal matter will fall with a small Baryon-number dependance in the earth's field. All of these predictions violate the Weak Equivalence Principle, a cornerstone of General Relativity, but are consistent with CPT conservation. In our approved experiment at LEAR (PS-200) we will test the Weak Equivalence Principle for antimatter by measuring the gravitational acceleration of the antiproton. Through a series of deceleration stages, antiprotons from LEAR will be lowered in energy to ∼4 Kelvin at which energy the gravitational effect will be measureable. The measurement will employ the time-of-flight technique wherein the antiprotons are released vertically in a drift tube. The spectrum of time-of-flight measurements can be used to extract the gravitational acceleration experienced by the particles. The system will be calibrated using H- ions which simulates the electromagnetic behavior of the antiproton, yet is a baryon to ∼0.1%. To extract the gravitational acceleration of the antiproton relative to the H- ion with a statistical precision of 1% will require the release of ∼106 to 107 particles

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

    International Nuclear Information System (INIS)

    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

  18. Unraveling resistive versus collisional contributions to relativistic electron beam stopping power in cold-solid and in warm-dense plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Vauzour, B. [CNRS, CEA, CELIA (Centre Lasers Intenses et Applications), Univ. Bordeaux, UMR 5107, F-33405 Talence (France); Laboratoire d' Optique Appliquée, ENSTA-CNRS-Ecole Polytechnique, UMR 7639, 91761 Palaiseau (France); Debayle, A. [ETSI Aeronáuticos, Universidad Politécnica de Madrid, Madrid (Spain); CEA, DAM, DIF, F-91297 Arpajon (France); Vaisseau, X.; Hulin, S.; Nicolaï, Ph.; Dorchies, F.; Fourment, C.; D' Humières, E.; Tikhonchuk, V. T.; Santos, J. J., E-mail: santos.joao@celia.u-bordeaux1.fr [CNRS, CEA, CELIA (Centre Lasers Intenses et Applications), Univ. Bordeaux, UMR 5107, F-33405 Talence (France); Schlenvoigt, H.-P.; Baton, S. D.; Yahia, V. [LULI, Ecole Polytechnique, CNRS/CEA/UPMC, 91128 Palaiseau Cedex (France); Batani, D. [CNRS, CEA, CELIA (Centre Lasers Intenses et Applications), Univ. Bordeaux, UMR 5107, F-33405 Talence (France); Dipartimento di Fisica, Università di Milano-Bicocca, Milano 20126 (Italy); Honrubia, J. J. [ETSI Aeronáuticos, Universidad Politécnica de Madrid, Madrid (Spain); Beg, F. N.; Chawla, S.; Jarrot, L. C. [University of California, San Diego, La Jolla, California 92093 (United States); Benocci, R.; Volpe, L. [Dipartimento di Fisica, Università di Milano-Bicocca, Milano 20126 (Italy); and others

    2014-03-15

    We present results on laser-driven relativistic electron beam propagation through aluminum samples, which are either solid and cold or compressed and heated by laser-induced shock. A full numerical description of fast electron generation and transport is found to reproduce the experimental absolute K{sub α} yield and spot size measurements for varying target thicknesses, and to sequentially quantify the collisional and resistive electron stopping powers. The results demonstrate that both stopping mechanisms are enhanced in compressed Al samples and are attributed to the increase in the medium density and resistivity, respectively. For the achieved time- and space-averaged electronic current density, 〈j{sub h}〉∼8×10{sup 10} A/cm{sup 2} in the samples, the collisional and resistive stopping powers in warm and compressed Al are estimated to be 1.5 keV/μm and 0.8 keV/μm, respectively. By contrast, for cold and solid Al, the corresponding estimated values are 1.1 keV/μm and 0.6 keV/μm. Prospective numerical simulations involving higher j{sub h} show that the resistive stopping power can reach the same level as the collisional one. In addition to the effects of compression, the effect of the transient behavior of the resistivity of Al during relativistic electron beam transport becomes progressively more dominant, and for a significantly high current density, j{sub h}∼10{sup 12} A/cm{sup 2}, cancels the difference in the electron resistive stopping power (or the total stopping power in units of areal density) between solid and compressed samples. Analytical calculations extend the analysis up to j{sub h}=10{sup 14} A/cm{sup 2} (representative of the full-scale fast ignition scenario of inertial confinement fusion), where a very rapid transition to the Spitzer resistivity regime saturates the resistive stopping power, averaged over the electron beam duration, to values of ∼1 keV/μm.

  19. Antiproton-nucleus interaction

    Science.gov (United States)

    Cugnon, J.; Vandermeulen, J.

    The antiproton-nucleus physics is reviewed. On the experimental side, the recent results obtained at the LEAR, BNL and KEK facilities are analyzed. A brief summary of the main pp and pn experimental data is also given. The antiproton-nucleus interaction can lead to elasic, inelastic and charge exchange scattering and to annihilation. The latter is very dominant. The scattering cross-sections are usually analyzed in terms of complex potential models. The relationship between potentials, charge conjugation and Dirac phenomenology is discussed. Much emphasis is put on the dynamics of the antiproton annihilation on nuclei. The energy transfer, pion absorption and target response are analyzed within the intranuclear cascade model. Special interest is devoted to strangeness production, hypernucleus formation and possible annihilation on two nucleons. Signatures for this new process are searched in experimental data. Finally, the highly debated question of quark-gluon formation is analyzed. Cet article constitue une revue de la physique antiproton-noyau. Du point de vue expérimental, cette revue porte particulièrement sur les récents résultats obtenus à LEAR, BNL et KEK. On y a aussi inclus une mise à jour des faits expérimentaux principaux pour pp et pn. L'interaction antiproton-noyau conduit à la diffusion élastique, inélastique et d'xA9change de charge et à des processus d'annihilation. Habituellement, les expériences de diffusion sont analysées en termes de potentiels complexes. La relation entre ces potentiels, la conjugaison de charge et la phénoménologie de Dirac est discutée. On s'est particulièrement intéressé à la dynamique de l'annihilation d'antiprotons sur des noyaux. Le transfert d'énergie, l'absorption de pions et la réponse de la cible sont analysés dans le cadre du modèle de cascade intranucléaire. Certains autres points sont discutés plus en détail: la production d'étrangeté, la formation d'hypernoyaux et l'annihilation sur

  20. 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...

  1. Primary population of antiprotonic helium states

    OpenAIRE

    Révai, J.; Shevchenko, N.V.(Nuclear Physics Institute, Řež, 25068, Czech Republic)

    2003-01-01

    A full quantum mechanical calculation of partial cross-sections leading to different final states of antiprotonic helium atom was performed. Calculations were carried out for a wide range of antiprotonic helium states and incident (lab) energies of the antiproton.

  2. 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.

  3. Production of ultra slow antiprotons, its application to atomic collisions and atomic spectroscopy - ASACUSA project

    International Nuclear Information System (INIS)

    The Atomic Spectroscopy And Collisions Using Slow Antiprotons (ASACUSA) project aims at studying collision dynamics with slow antiprotons and high precision spectroscopy of antiprotonic atoms. To realize these purposes, the production of high quality ultra slow antiproton beams is essential, which is achieved by the combination of antiproton decelerator (AD) from 3 GeV to 5 MeV, a radio frequency quadrupole (RFQ) decelerator from 5 MeV to 50 keV, and finally an electromagnetic trap from 50 keV to 10 eV. From the atomic physics point of view, an antiproton is an extremely heavy electron and/or a negatively charged proton, i.e., the antiproton is a unique tool to shed light on collision dynamics from the other side of the world. In addition to this fundamentally important feature, the antiproton has also a big practical advantage, i.e., it annihilates with the target nuclei emitting several energetic pions, which provides high detection efficiency with very good time resolution. Many-body effects which are of great importance to several branches of science will be studied through ionization and antiprotonic atom formation processes under single collision conditions. Various antiprotonic atoms including protonium (p anti-p) are expected to be meta-stable in vacuum, which is never true for those in dense media except for antiprotonic helium. High precision spectroscopy of protonium will for the first time become feasible benefited by this meta-stability. The present review reports briefly the production scheme of ultra slow antiproton beams and several topics proposed in the ASACUSA project

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

    CERN Multimedia

    Matsuda, Y; Lodi-rizzini, E; Kuroda, N; Schettino, G; Hori, M; Soter, A; Pirkl, W; Mascagna, V; Malbrunot, C L S; Yamazaki, Y; Eades, J; Simon, M; Massiczek, O; Sauerzopf, C; Breuker, H; 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...

  5. Antiproton Powered Gas Core Fission Rocket

    International Nuclear Information System (INIS)

    Extensive research in recent years has demonstrated that 'at rest' annihilation of antiprotons in the uranium isotope U238 leads to fission at nearly 100% efficiency. The resulting highly-ionizing, energetic fission fragments can heat a suitable medium to very high temperatures, making such a process particularly suitable for space propulsion applications. Such an ionized medium, which would serve as a propellant, can be confined by a magnetic field during the heating process, and subsequently ejected through a magnetic nozzle to generate thrust. The gasdynamic mirror (GDM) magnetic configuration is especially suited for this application since the underlying confinement principle is that the plasma be of such density and temperature as to make the ion-ion collision mean free path shorter than the plasma length. Under these conditions the plasma behaves like a fluid, and its escape from the system is analogous to the flow of a gas into vacuum from a vessel with a hole. For the system we propose we envisage radially injecting atomic or U238 plasma beam at a pre-determined position and axially pulsing an antiproton beam which upon interaction with the uranium target gives rise to near isotropic ejection of fission fragments with a total mass of 212 amu and total energy of about 160 MeV. These particles, along with the annihilation products (i.e. pions and muons) will heat the background U238 gas - inserted into the chamber just prior to the release of the antiproton - to one keV temperature. Preliminary analysis reveals that such a propulsion system can produce a specific impulse of about 3000 seconds at a thrust of about 50 kN. When applied to a round trip Mars mission, we find that such a journey can be accomplished in about 142 days with 2 days of thrusting and requiring only one gram of antiprotons to achieve it

  6. Antiproton Powered Gas Core Fission Rocket

    Science.gov (United States)

    Kammash, T.

    Extensive research in recent years has demonstrated that “at rest” annihilation of antiprotons in the uranium isotope U238 leads to fission at nearly 100% efficiency. The resulting highly-ionizing, energetic fission fragments can heat a suitable medium to very high temperatures, making such a process particularly suitable for space propulsion applications. Such an ionized medium, which would serve as a propellant, can be confined by a magnetic field during the heating process, and subsequently ejected through a magnetic nozzle to generate thrust. The gasdynamic mirror (GDM) magnetic configuration is especially suited for this application since the underlying confinement principle is that the plasma be of such density and temperature as to make the ion-ion collision mean free path shorter than the plasma length. Under these conditions the plasma behaves like a fluid, and its escape from the system is analogous to the flow of a gas into vacuum from a vessel with a hole. For the system we propose we envisage radially injecting atomic or U238 plasma beam at a pre-determined position and axially pulsing an antiproton beam which upon interaction with the uranium target gives rise to near isotropic ejection of fission fragments with a total mass of 212 amu and total energy of about 160 MeV. These particles, along with the annihilation products (i.e. pions and muons) will heat the background U238 gas - inserted into the chamber just prior to the release of the antiproton - to one keV temperature. Preliminary analysis reveals that such a propulsion system can produce a specific impulse of about 3000 seconds at a thrust of about 50 kN. When applied to a round trip Mars mission, we find that such a journey can be accomplished in about 142 days with 2 days of thrusting and requiring only one gram of antiprotons to achieve it.

  7. 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...

  8. 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.

  9. 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...

  10. 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...

  11. 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...

  12. Large amounts of antiproton production by heavy ion collision

    International Nuclear Information System (INIS)

    To produce large amounts of antiprotons, on the order of several grams/year, use of machines to produce nuclear collisions are studied. These can be of either proton-proton, proton-nucleus and nucleus-nucleus in nature. To achieve high luminosity colliding beams, on the order of 1041 m/cm2, a self-colliding machine is required, rather than a conventional circular colliding type. The self-colliding machine can produce additional antiprotons through successive collisions of secondary particles, such as spectator nucleons. A key problem is how to collect the produced antiprotons without capture by beam nuclei in the collision zone. Production costs for anti-matter are projected for various energy source options and technology levels. Dedicated facilities using heavy ion collisions could produce antiproton at substantially less than 1 million $/milligram. With co-production of other valuable products, e.g., nuclear fuel for power reactors, antiproton costs could be reduced to even lower values

  13. A low-energy antiproton detector prototype for AFIS

    Energy Technology Data Exchange (ETDEWEB)

    Meng, Lingxin; Greenwald, Daniel; Hahn, Alexander; Hauptmann, Philipp; Konorov, Igor; Losekamm, Martin; Paul, Stephan; Poeschl, Thomas; Renker, Dieter [Technische Universitaet Muenchen (Germany)

    2014-07-01

    Antiprotons are produced in interactions of primary cosmic rays with earth's exosphere, where a fraction of them will be confined in the geomagnetic field in the inner van Allen Belt. The antiproton-to-proton flux ratio predicted by theory is in good agreement with recent results from the South Atlantic Anomaly (SAA) published by the PAMELA collaboration. We have designed the AFIS (Antiproton Flux in Space) project in order to extend the measurable range of antiprotons towards the low-energy region. In scope of this project a small antiproton detector consisting of scintillating fibers and silicon photomultipliers is being developed as payload for a CubeSat traversing the SAA in Low Earth Orbit. For the proof of concept we have built a prototype called ''CubeZero'' which completed its first test using pion and proton beams at PSI, Switzerland. Our primary goal was to investigate on the performance of tracking and Bragg peak identification in hardware and software. Analysis of detector performance based on data taken during this beam test is presented in this talk.

  14. Low energy antiproton physics

    International Nuclear Information System (INIS)

    This paper summarizes the present experimental and theoretical status of antinucleon-nucleon (bar NN) interactions at low energy (below 2 GeV/c). The authors discuss elastic scattering, hyperon pair production, and annihilation into mesonic channels, including the search for exotic meson states in the annihilation debris. New results from the Low Energy Antiproton Ring (LEAR) at CERN, from KEK in Japan, and from Brookhaven National Laboratory (BNL) are now available. Some of the experiments and their comparison to theoretical predictions have been reviewed earlier. The authors extend these reviews to more recent data and theoretical calculations

  15. Electron cooling for low-energy antiprotons

    International Nuclear Information System (INIS)

    Divergence and size of stored ion beams can be reduced superimposing on them an intense, monoenergetic electron beam with little transverse motion ('electron cooling'). The present work first considers the theoretical foundations of the method and then describes the planning and construction of an electron beam device for cooling antiprotons with MeV energies in the storage ring LEAR and CERN. With respect to the quantitative description of the method, the microscopic processes during the damping of the ion motion, the effect of the damping on an ion in a storage ring, and the properties of the intense, magnetically guided electron beam are discussed. Special attention is paid to the improvement of ion beam cooling due to the magnetic field guiding the electron beam. The electron beam device, operated in ultra-high vacuum, and the experience gained during its construction are described; experiments performed during the test period are presented. The work further develops a numerical simulation of electron cooling on the basis of the theory discussed. Given realistic external parameters, the simulation yields cooling times and equilibrium states of the ion beam during electron cooling in a storage ring. Finally, non-destructive methods for measuring the velocity distribution in the electron beam are described, which may prove helpful for optimizing the beam cooling. (orig.)

  16. Absolute calibration of the antiproton detection efficiency for BESS below 1 GeV

    CERN Document Server

    Asaoka, Y; Yoshida, T; Abe, K; Anraku, K; Fujikawa, M; Fuke, H; Haino, S; Izumi, K; Maeno, T; Makida, Y; Matsui, N; Matsumoto, H; Matsunaga, H; Motoki, M; Nozaki, M; Orito, S; Sanuki, T; Sasaki, M; Shikaze, Y; Sonoda, T; Suzuki, J; Tanaka, K; Toki, Y; Yamamoto, A

    2001-01-01

    An accelerator beam experiment was performed using a low-energy antiproton beam to measure the antiproton detection efficiency of the BESS detector. Measured and calculated efficiencies derived from the BESS Monte Carlo simulation based on GEANT/GHEISHA showed good agreement. With the detailed verification of the BESS simulation, results demonstrate that the relative systematic error of detection efficiency derived from the BESS simulation is within 5 %, being previously estimated as 15 % which was the dominant uncertainty for measurements of cosmic-ray antiproton flux.

  17. Stopping Gluinos

    Energy Technology Data Exchange (ETDEWEB)

    Arvanitaki, A.; Dimopoulos, S.; /Stanford U., Phys. Dept.; Pierce, A.; /SLAC /Stanford U., Phys. Dept.; Rajendran, S.; Wacker, J.; /Stanford U., Phys. Dept.

    2005-06-29

    Long lived gluinos are the trademark of split susy. They form R-hadrons that, when charged, efficiently lose energy in matter via ionization. Independent of R-spectroscopy and initial hadronization, a fraction of R-hadrons become charged while traversing a detector. This results in a large number of stopped gluinos at present and future detectors. For a 300 GeV gluino, 10{sup 6} will stop each year in LHC detectors, while several hundred stop in detectors during Run II at the Tevatron. The subsequent decays of stopped gluinos produce distinctive depositions of energy in calorimeters with no activity in either the tracker or the muon chamber.

  18. Photon and dilepton production at the Facility for Proton and Anti-Proton Research and beam-energy scan at the Relativistic Heavy-Ion Collider using coarse-grained microscopic transport simulations

    Science.gov (United States)

    Endres, Stephan; van Hees, Hendrik; Bleicher, Marcus

    2016-05-01

    We present calculations of dilepton and photon spectra for the energy range Elab=2 A to35 A GeV which will be available for the Compressed Baryonic Matter (CBM) experiment at the future Facility for Proton and Anti-Proton Research (FAIR). The same energy regime will also be covered by phase II of the beam-energy scan at the Relativistic Heavy-Ion Collider (RHIC-BES). Coarse-grained dynamics from microscopic transport calculations of the Ultrarelativistic Quantum Molecular Dynamics (UrQMD) model is used to determine temperature and chemical potentials, which allows for the use of dilepton and photon-emission rates from equilibrium quantum-field-theory calculations. The results indicate that nonequilibrium effects, the presence of baryonic matter, and the creation of a deconfined phase might show up in specific manners in the measurable dilepton invariant-mass spectra and in the photon transverse-momentum spectra. However, as the many influences are difficult to disentangle, we argue that the challenge for future measurements of electromagnetic probes will be to provide a high precision with uncertainties much lower than in previous experiments. Furthermore, a systematic study of the whole energy range covered by CBM at FAIR and RHIC-BES is necessary to discriminate between different effects, which influence the spectra, and to identify possible signatures of a phase transition.

  19. 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.

  20. 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.

  1. Proton-antiproton collider physics

    CERN Document Server

    Altarelli, Guido

    1989-01-01

    This volume reviews the physics studied at the CERN proton-antiproton collider during its first phase of operation, from the first physics run in 1981 to the last one at the end of 1985. The volume consists of a series of review articles written by physicists who are actively involved with the collider research program. The first article describes the proton-antiproton collider facility itself, including the antiproton source and its principle of operation based on stochastic cooling. The subsequent six articles deal with the various physics subjects studied at the collider. Each article descr

  2. Status of antiproton accumulation and cooling at Fermilab's Recycler

    International Nuclear Information System (INIS)

    The Recycler ring is an 8 GeV permanent magnet storage ring where antiprotons are accumulated and prepared for Fermilab's Tevatron Collider program. With the goal of maximizing the integrated luminosity delivered to the experiments, storing, cooling and extracting antiprotons with high efficiency has been pursued. Over the past two years, while the average accumulation rate doubled, the Recycler continued to operate at a constant level of performance thanks to changes made to the Recycler Electron Cooler (energy stability and regulation, electron beam optics), RF manipulations and operating procedures. In particular, we discuss the current accumulation cycle in which ∼ 400 x 1010 antiprotons are accumulated and extracted to the Tevatron every ∼15 hours

  3. 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...

  4. Heating of nuclear matter and multifragmentation: antiprotons vs. pions

    International Nuclear Information System (INIS)

    Heating of nuclear matter with 8 GeV/c bar p and π- beams has been investigated in an experiment conducted at BNL AGS accelerator. All charged particles from protons to Z ≅ 16 were detected using the Indiana Silicon Sphere 4π array. Significant enhancement of energy deposition in high multiplicity events is observed for antiprotons compared to other hadron beams. The experimental trends are qualitatively consistent with predictions from an intranuclear cascade code

  5. Heating of nuclear matter and multifragmentation : antiprotons vs. pions.

    Energy Technology Data Exchange (ETDEWEB)

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

    1999-05-03

    Heating of nuclear matter with 8 GeV/c {bar p} and {pi}{sup {minus}} beams has been investigated in an experiment conducted at BNL AGS accelerator. All charged particles from protons to Z {approx_equal} 16 were detected using the Indiana Silicon Sphere 4{pi} array. Significant enhancement of energy deposition in high multiplicity events is observed for antiprotons compared to other hadron beams. The experimental trends are qualitatively consistent with predictions from an intranuclear cascade code.

  6. Annihilation of low energy antiprotons in silicon

    CERN Document Server

    Aghion, S; Belov, A S; Bonomi, G; Bräunig, P; Bremer, J; Brusa, R S; Burghart, G; Cabaret, L; Caccia, M; Canali, C; Caravita, R; Castelli, F; Cerchiari, G; Cialdi, S; Comparat, D; Consolati, G; Derking, J H; Di Domizio, S; Di Noto, L; Doser, M; Dudarev, A; Ferragut, R; Fontana, A; Genova, P; Giammarchi, M; Gligorova, A; Gninenko, S N; Haider, S; Harasimovic, J; Huse, T; Jordan, E; Jørgensen, L V; Kaltenbacher, T; Kellerbauer, A; Knecht, A; Krasnický, D; Lagomarsino, V; Magnani, A; Mariazzi, S; Matveev, V A; Moia, F; Nebbia, G; Nédélec, P; Pacifico, N; Petrácek, V; Prelz, F; Prevedelli, M; Regenfus, C; Riccardi, C; Røhne, O; Rotondi, A; Sandaker, H; Susa, A; Vasquez, M A Subieta; Špacek, M; Testera, G; Welsch, C P; Zavatarelli, S

    2013-01-01

    The goal of the AE$\\mathrm{\\bar{g}}$IS experiment at the Antiproton Decelerator (AD) at CERN, is to measure directly the Earth's gravitational acceleration on antimatter. To achieve this goal, the AE$\\mathrm{\\bar{g}}$IS collaboration will produce a pulsed, cold (100 mK) antihydrogen beam with a velocity of a few 100 m/s and measure the magnitude of the vertical deflection of the beam from a straight path. The final position of the falling antihydrogen will be detected by a position sensitive detector. This detector will consist of an active silicon part, where the annihilations take place, followed by an emulsion part. Together, they allow to achieve 1$%$ precision on the measurement of $\\bar{g}$ with about 600 reconstructed and time tagged annihilations. We present here, to the best of our knowledge, the first direct measurement of antiproton annihilation in a segmented silicon sensor, the first step towards designing a position sensitive silicon detector for the AE$\\mathrm{\\bar{g}}$IS experiment. We also pr...

  7. 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.

  8. 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.

  9. Measurement of low-energy antiproton detection efficiency in BESS below 1 GeV

    CERN Document Server

    Asaoka, Y; Yoshida, T; Abe, K; Anraku, K; Fujikawa, M; Fuke, H; Haino, S; Izumi, K; Maeno, T; Makida, Y; Matsui, N; Matsumoto, H; Matsunaga, H; Motoki, M; Nozaki, M; Orito, S; Sanuki, T; Sasaki, M; Shikaze, Y; Sonoda, T; Suzuki, J; Tanaka, K; Toki, Y; Yamamoto, A

    2002-01-01

    An accelerator experiment was performed using a low-energy antiproton beam to measure antiproton detection efficiency of BESS, a balloon-borne spectrometer with a superconducting solenoid. Measured efficiencies showed good agreement with calculated ones derived from the BESS Monte Carlo simulation based on GEANT/GHEISHA. With detailed verification of the BESS simulation, the relative systematic error of detection efficiency derived from the BESS simulation has been determined to be +-5%, compared with the previous estimation of +-15% which was the dominant uncertainty for measurements of cosmic-ray antiproton flux.

  10. Remote antiproton sources

    International Nuclear Information System (INIS)

    Antiprotons are well on their way to becoming a standard laboratory commodity. Heavy utilization of LEAR is ushering in a new era where p's achieve their logical potential, equal to that of e-,e+,H-, as controlled probes and experimental building blocks. The uniqueness and usefulness of - /SUB p/ 's for studies at low (table top) energies is well documented. The main stumbling block to universal pursuit of such studies is the overhead of - /SUB p/ production. The stability of the - /SUB p/ thus makes cogent an investigation of possibilities and limits to transporting - /SUB p/ 's in quantity. I base my discussion on LEAR as the source of - /SUB p/ 's for bottling, since it is the only concrete example to work with at present. Two other lines of contemporary research then, largely in atomic physics, pioneered by Dehmelt and collaborators, aimed at precision studies of clouds of, or single e /SUP +or-/ ,p /SUP +or-/ , or ions in large storage time traps. Second, there is work, experimental and theoretical, from the plasma physics tradition aimed at characterizing non neutral plasmas

  11. Capture of slow antiprotons by helium atoms

    OpenAIRE

    Revai, J.; Shevchenko, N.V.(Nuclear Physics Institute, Řež, 25068, Czech Republic)

    2004-01-01

    A consistent quantum mechanical calculation of partial cross-sections leading to different final states of antiprotonic helium atom was performed. For the four-body scattering wave function, corresponding to the initial state, as well as for the antiprotonic helium wave function, appearing in the final tate, adiabatic approximations was used. Calculations were carried out for a wide range of antiprotonic helium states and incident energies of the antiproton. Obtained energy dependances of som...

  12. 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...

  13. Measurement of antiproton-proton cross sections at low momenta

    International Nuclear Information System (INIS)

    The present thesis describes an experiment which serves for the study of the antiproton-proton interaction at laboratory momenta between 150 MeV/c and 600 MeV/c. The arrangement permits the measurement of differential cross sections of the elastic scattering and the charge-exchange reaction as well as the cross section of the annihilation into charged and neutral pions. By the availability of an intense beam with low momentum uncertainty from the LEAR storage ring for low energy antiprotons at CERN a clear improvement of the measurement accuracy compared to earlier experiments at separated antiproton beams can be reached. A prototype of the antineutron calorimeter used for the measurement of the angular distribution of the charge-exchange reaction was subjected to a careful test in a separated beam. The results were compared with the results of a Monte-Carlo simulation of the antineutron detection. The cross sections measured in two beam periods in November and December 1983 are consistent with the published data in the hitherto available momentum range above about 350 MeV/c. Especially in the cross section of the annihilation into charged pions a statistically significant signal at a mass of 1937 MeV/c2 appears. However further measurements are necessary to study all systematic causes of errors. (orig.)

  14. Antiprotons in the Cosmic Rays

    Science.gov (United States)

    Nutter, Scott

    1999-10-01

    The HEAT (High Energy Antimatter Telescope) collaboration flew in May 1999 a balloon-borne instrument to measure the relative abundance of antiprotons and protons in the cosmic rays to kinetic energies of 30 GeV. The instrument uses a multiple energy loss technique to measure the Lorentz factor of through-going cosmic rays, a magnet spectrometer to measure momentum, and several scintillation counters to determine particle charge and direction (up or down in the atmosphere). The antiproton/proton abundance ratio as a function of energy is a probe of the propagation environment of protons through the galaxy. Existing measurements indicate a higher than expected value at both high and low energies. A confirming measurement could indicate peculiar antiproton sources, such as WIMPs or supersymmetric darkmatter candidates. A description of the instrument, details of the flight and instrument performance, and status of the data analysis will be given.

  15. 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.

  16. Measurement of interaction between antiprotons

    CERN Document Server

    ,

    2015-01-01

    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 since acquired was derived from studies made on nucleons or nuclei. Although antinuclei up to antihelium-4 have been discovered and their masses measured, we have no direct knowledge of the nuclear force between antinucleons. Here, we study antiproton pair correlations among data taken by the STAR experiment at the Relativistic Heavy Ion Collider and show that the force between two antiprotons is attractive. In addition, we report two key parameters that characterize the corresponding strong interaction: namely, the scattering length (f0) and effective range (d0). As direct information on the interaction between two antiprotons, one of the simplest systems of antinucleons, our result provides a fundamental ingr...

  17. Antiproton annihilation in quantum chromodynamics

    International Nuclear Information System (INIS)

    Anti-proton annihilation has a number of important advantages as a probe of QCD in the low energy domain. Exclusive reaction in which complete annihilation of the valance quarks occur. There are a number of exclusive and inclusive /bar p/ reactions in the intermediate momentum transfer domain which provide useful constraints on hadron wavefunctions or test novel features of QCD involving both perturbative and nonperturbative dynamics. Inclusive reactions involving antiprotons have the advantage that the parton distributions are well understood. In these lectures, I will particularly focus on lepton pair production /bar p/A → /ell//bar /ell//X as a means to understand specific nuclear features in QCD, including collision broadening, breakdown of the QCD ''target length condition''. Thus studies of low to moderate energy antiproton reactions with laboratory energies under 10 GeV could give further insights into the full structure of QCD. 112 refs., 40 figs

  18. 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.

  19. Perspectives for low energy antiproton physics at FAIR

    OpenAIRE

    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 possibilitie...

  20. 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.

  1. Biological Effectiveness of Antiproton Annihilation

    DEFF Research Database (Denmark)

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

    2004-01-01

    A new experiment, AD-4/ACE (antiproton cell experiment), has been approved by the CERN Research Board. The experiment is scheduled to begin taking data in June and continue through the 2003 run cycle. The experiment is designed to determine whether or not the densely ionizing particles emanating...

  2. 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...

  3. Antiproton Stacking in the Recycler

    CERN Document Server

    Burov, A

    2003-01-01

    Possibilities to accumulate antiprotons in the Recycler are considered for three different cases: with current stochastic cooling, with upgraded stochastic cooling and with electron cooling. With stochastic cooling only, even upgraded, Recycler looks hardly useful. However, with electron cooling at its goal parameters and reasonably good vacuum in the Recycler, this machine would be efficient.

  4. Proton-Antiproton Collider Physics

    OpenAIRE

    Shochet, Melvyn J.

    1995-01-01

    Comment: Summary of the 10th Topical Workshop on Proton-Antiproton Collider Physics, Fermilab, May 9-13, 1995. Postscript file (34 pages with 82 embedded figures; 5.7 MB) available at http://www-cdf.fnal.gov/physics/conf95/cdf3225_pbarp_wkshp_summary.ps

  5. Measurement of interaction between antiprotons

    Czech Academy of Sciences Publication Activity Database

    Adamczyk, L.; Bielčík, J.; Bielčíková, Jana; Federič, Pavol; Chaloupka, P.; Rusňák, Jan; Rusňáková, O.; Šimko, Miroslav; Šumbera, Michal; Tlustý, David; Trzeciak, B. A.; Vértési, Robert

    2015-01-01

    Roč. 527, č. 7578 (2015), s. 345-348. ISSN 0028-0836 R&D Projects: GA ČR GA13-20841S Institutional support: RVO:61389005 Keywords : STAR collaboration * antiprotons * protons Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 41.456, year: 2014

  6. Antiproton production in Au + Au collisions at 11.7 A·GeV/c

    International Nuclear Information System (INIS)

    We investigated the dependence of antiproton yields on the number of wounded projectile nucleons (Nproj). The dN/dy/Nproj 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/π-, p/π-, K-/π-, K+/π-, and π+/π- at 1.2proj in Au+Au collisions. Only the ratio of p-bar/π- decreases rapidly, while the ratios of p/π-, K+/π-, and K-/π- increase, and π+/π- stays constant. These observations suggest that in the AGS energy regime, the absorption effect of antiprotons 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

  7. Antiproton production at 0 degrees for Si + A and Au + A collisions at the AGS

    International Nuclear Information System (INIS)

    We present results on antiproton production obtained in the AGS experiments E858 and preliminary results of E878. The yields of antiprotons in Si + A collisions are shown to sale with number of first collisions. The rapidity distributions for all targets (Au, Cu and Al) and both beams (si at 14.6 GeV/c and A at 11. GeV/c) have gaussian shapes peaking at yNN and with similar standard deviations. From E878 we report a difference in the shape of the antiproton rapidity distributions obtained from two samples of the data populated with central and peripheral events respectively. In A induced reactions the A dependence of the antiproton yields is small

  8. Ion stopping in heated targets

    International Nuclear Information System (INIS)

    Ion stopping departs from classical, cold material values as the target material heats to appreciable ionization levels. The authors are investigating this phenomenon experimentally on the Proto I accelerator with a radial, Applied-B field ion diode. When the beam is focused to 0.5 TW/cm3 on thin aluminum foil targets the time-resolved departure from cold stopping is clear. Their observations and early interpretations will be presented. 9 references, 9 figures

  9. Measurement of asymmetries and differential cross sections in antiproton-proton elastic scattering at momenta between 497 and 1550 MeV/c

    International Nuclear Information System (INIS)

    An intermediate energy antiproton proton (anti pp) elastic scattering experiment is described. The data comprise a set of 15 measurements of the differential cross section and the asymmetry between 497 and 1550 MeV/c antiproton momentum. The measurements were carried out using the high quality antiproton beam provided by the Low Energy Antiproton Ring (LEAR) at CERN. A conventional polarized target was used, consisting of pentanol. The motivation for the measurements is the study of the anti pp interaction by providing data on the spin observable Aon in a momentum range where it has never been measured before. 56 refs.; 55 figs.; 40 tabs

  10. Neutron Fluence in Antiproton Radiotherapy, Measurements and Simulations

    International Nuclear Information System (INIS)

    Introduction: 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. Materials and Methods: Using a polystyrene phantom as a moderator, we have performed absolute fluence measurements of the thermalized part of the fast neutron spectrum using Lithium-6 and -7 Fluoride TLD pairs. The results were compared with the Monte Carlo particle transport code FLUKA. Results: The experimental results are found to be in good agreement with simulations. The thermal neutron kerma resulting from the measured thermal neutron fluence is insignificant compared to the contribution from fast neutrons. Discussion: The secondary neutron fluences encountered in antiproton therapy are found to be similar to values calculated for pion treatment, however exact modeling under more realistic treatment scenarios is still required to quantitatively compare these treatment modalities.

  11. Radiation studies in the antiproton source

    International Nuclear Information System (INIS)

    Experiment E760 has a lead glass (Pb-G) calorimeter situated in the antiproton source tunnel in the accumulator ring at location A50. This location is exposed to radiation from several sources during antiproton stacking operations. A series of radiation studies has been performed over the last two years to determine the sources of this radiation and as a result, some shielding has been installed in the antiproton source in order to protect the lead glass from radiation damage

  12. Interaction of antiproton with nuclei

    Czech Academy of Sciences Publication Activity Database

    Hrtánková, Jaroslava; Mareš, Jiří

    Vol. 234. Dordrecht: Springer, 2015, s. 93-98. ISSN 0304-3843. [5th International Conference on Exotic Atoms and Related Topics (EXA). Vienna (AT), 15.09.2014-19.09.2014] R&D Projects: GA ČR(CZ) GAP203/12/2126 Institutional support: RVO:61389005 Keywords : antiproton-nucleus interaction * RMF model * G-parity Subject RIV: BE - Theoretical Physics

  13. Design study of an Antiproton Collector for the Antiproton Accumulator (ACOL)

    International Nuclear Information System (INIS)

    The Report gives a full description of an Antiproton Collector Ring which, placed around the existing Antiproton Accumulator at CERN, would enhance the antiproton flux available to both the SPS and LEAR by a factor of ten. The new ring and the focusing devices which precede it are designed to accept a much larger fraction of the antiproton production cone from the target. Each pulse of particles will be pre-cooled before being fed to the Antiproton Accumulator, where improved stochastic cooling systems will build up the stack. A full list of parameters is included. (orig.)

  14. 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

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

    International Nuclear Information System (INIS)

    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 T>60;T>62; of net protons also increase with system size. The h- rapidity density scales with the number of participant nucleons for nuclear collisions, where their T>60;T>62; is independent of system size. The T>60;T>62; 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

  16. The Fermilab proton-antiproton collider upgrades

    International Nuclear Information System (INIS)

    The plans for increases in the Tevatron proton-antiproton collider luminosity in the near future (Run II) and the more distant future (TeV33) are described. While there are many important issues, the fundamental requirement is to produce more antiprotons and to use them more efficiently

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

    International Nuclear Information System (INIS)

    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.)

  18. 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)

  19. 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 ...

  20. Longitudinal momentum mining of antiprotons at the Fermilab Recycler: past, present and future

    Energy Technology Data Exchange (ETDEWEB)

    Bhat, C.M.; Chase, B.E.; Gattuso, C.; Joireman, P.W.; /Fermilab

    2007-06-01

    The technique of longitudinal momentum mining (LMM)[1] in the Fermilab Recycler was adopted in early 2005 to extract thirty-six equal intensity and equal 6D-emittance antiproton bunches for proton-antiproton collider operation in the Tevatron. Since that time, several improvements have been made in the Recycler and the mining technique to handle higher intensity beams. Consequently, the Recycler has become a key contributor to the increased luminosity performance observed during Tevatron Run IIb. In this paper, we present an overview of the improvements and the current status of the momentum mining technique.

  1. Longitudinal momentum mining of antiprotons at the Fermilab Recycler: past, present and future

    International Nuclear Information System (INIS)

    The technique of longitudinal momentum mining (LMM)[1] in the Fermilab Recycler was adopted in early 2005 to extract thirty-six equal intensity and equal 6D-emittance antiproton bunches for proton-antiproton collider operation in the Tevatron. Since that time, several improvements have been made in the Recycler and the mining technique to handle higher intensity beams. Consequently, the Recycler has become a key contributor to the increased luminosity performance observed during Tevatron Run IIb. In this paper, we present an overview of the improvements and the current status of the momentum mining technique

  2. The TRIUMF stopped π-μ channel

    International Nuclear Information System (INIS)

    The TRIUMF stopped π-μ channel (M9) is described and the measured optical parameters are compared with design values. Measured beam characteristics of pions and muons for several different momenta are reported for protons incident on Be and Cu production targets. A beam of cloud muons at the channel momentum, from π decays near the production target, has been obtained having a high stopping density and small spot size. (orig.)

  3. 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...

  4. The measurement of antiproton-proton total cross sections and small-angle elastic scattering at low momentum

    International Nuclear Information System (INIS)

    In this thesis two low-momentum antiproton-proton (anti pp) experiments are described. The first one is a set of 24 high statistics anti pp total cross section measurements as a function of the incoming antiproton momentum between p=388 MeV/c and p=599 MeV/c. These measurements simultaneously yield the charge exchange cross section (anti pp → anti nn). The second one comprises two high statistics anti pp small-angle elastic scattering measurements at p=233 MeV/c and p=272 MeV/c. The measurements were carried out using the high quality antiproton beam extracted from the Low Energy Antiproton Ring (LEAR) at CERN. The physics motivation for these experiments is a search for anti pp resonances or bound states on one hand, and a detailed study of the anti pp interaction on the other hand. (orig.)

  5. 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).

  6. Status of antiproton accumulation and cooling at Fermilab's Recycler

    Energy Technology Data Exchange (ETDEWEB)

    Prost, L.R.; Bhat, C.M.; Broemmelsiek, D.; Burov, A.; Carlson, K.; Crisp, J.; Derwent, P.; Eddy, N.; Gattuso, C.; Hu, M.; Pruss, S.; /Fermilab

    2009-08-01

    The Recycler ring is an 8 GeV permanent magnet storage ring where antiprotons are accumulated and prepared for Fermilab's Tevatron Collider program. With the goal of maximizing the integrated luminosity delivered to the experiments, storing, cooling and extracting antiprotons with high efficiency has been pursued. Over the past two years, while the average accumulation rate doubled, the Recycler continued to operate at a constant level of performance thanks to changes made to the Recycler Electron Cooler (energy stability and regulation, electron beam optics), RF manipulations and operating procedures. In particular, we discuss the current accumulation cycle in which {approx} 400 x 10{sup 10} antiprotons are accumulated and extracted to the Tevatron every {approx}15 hours.

  7. 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.

  8. 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...

  9. Physics with ultra-low energy antiprotons

    International Nuclear Information System (INIS)

    The experimental observation that all forms of matter experience the same gravitational acceleration is embodied in the weak equivalence principle of gravitational physics. However no experiment has tested this principle for particles of antimatter such as the antiproton or the antihydrogen atom. Clearly the question of whether antimatter is in compliance with weak equivalence is a fundamental experimental issue, which can best be addressed at an ultra-low energy antiproton facility. This paper addresses the issue. 20 refs

  10. Low Energy Antiproton Experiments -- A Review

    OpenAIRE

    Jungmann, Klaus P.

    2005-01-01

    Low energy antiprotons offer excellent opportunities to study properties of fundamental forces and symmetries in nature. Experiments with them can contribute substantially to deepen our fundamental knowledge in atomic, nuclear and particle physics. Searches for new interactions can be carried out by studying discrete symmetries. Known interactions can be tested precisely and fundamental constants can be extracted from accurate measurements on free antiprotons ($\\bar{p}$'s) and bound two- and ...

  11. The construction and operating characteristics of a cathode strip chamber system designed to measure the reaction vertices of a stopping kaon beam

    CERN Document Server

    Ahmed, M W; Bertovic, I; Bjoraker, J; Chrien, R; Cui, X; Dehnhard, D; Empl, A; Furic, M; Gerald, J; Gill, R; Hungerford, E V; Juengst, H; Lan, K J; Liu, J H; Morris, C L; O'donnell, J M; Peng, J C; Petkovic, T; Pile, P; Planinic, M; Riedel, C M; Rusek, A; Sutter, R; Tang, L; Thiessen, H A; Youn, M; Zeps, V

    2001-01-01

    The design, construction, and performance of a segmented-target, cathode-strip, tracking-detector is discussed. The chamber was made of low-Z materials in order to allow photons to leave the target region. It was used to determine the reaction vertex of stopping kaons, and was successfully operated in a high-intensity kaon beamline at the Alternating Gradient Synchrotron at Brookhaven National Laboratory. The vertical and horizontal resolutions of the stopping kaon reaction positions were sigma sub X approx 0.454 mm and sigma sub Y approx 1.180 mm, respectively. The uncertainty in the longitudinal (Z) direction is given by one-half the thickness of a target segment.

  12. The construction and operating characteristics of a cathode strip chamber system designed to measure the reaction vertices of a stopping kaon beam

    International Nuclear Information System (INIS)

    The design, construction, and performance of a segmented-target, cathode-strip, tracking-detector is discussed. The chamber was made of low-Z materials in order to allow photons to leave the target region. It was used to determine the reaction vertex of stopping kaons, and was successfully operated in a high-intensity kaon beamline at the Alternating Gradient Synchrotron at Brookhaven National Laboratory. The vertical and horizontal resolutions of the stopping kaon reaction positions were σX∼0.454 mm and σY∼1.180 mm, respectively. The uncertainty in the longitudinal (Z) direction is given by one-half the thickness of a target segment

  13. The construction and operating characteristics of a cathode strip chamber system designed to measure the reaction vertices of a stopping kaon beam

    International Nuclear Information System (INIS)

    The design, construction, and performance of a segmented-target, cathode-strip, tracking-detector is discussed. The chamber was made of low-Z materials in order to allow photons to leave the target region. It was used to determine the reaction vertex of stopping kaons, and was successfully operated in a high-intensity kaon beamline at the Alternating Gradient Synchrotron at Brookhaven National Laboratory. The vertical and horizontal resolutions of the stopping kaon reaction positions were sigmaX∼0.454mm and sigmaY∼1.180mm, respectively. The uncertainty in the longitudinal (Z) direction is given by one-half the thickness of a target segment

  14. Beam-beam compensation studies in the Tevatron with electron lenses

    CERN Document Server

    Stancari, Giulio

    2013-01-01

    At the Fermilab Tevatron collider, we studied the feasibility of suppressing the antiproton head-on beam-beam tune spread using a magnetically confined 5-keV electron beam with Gaussian transverse profile overlapping with the circulating beam. When electron cooling of antiprotons was applied in regular Tevatron operations, the nonlinear head-on beam-beam effect on antiprotons was small. Therefore, we first focused on the operational aspects, such as beam alignment and stability, and on fundamental observations of tune shifts, tune spreads, lifetimes, and emittances. We also attempted two special collider stores with only 3 proton bunches colliding with 3 antiproton bunches, to suppress long-range forces and enhance head-on effects. We present here the results of this study and a comparison between numerical simulations and observations. These results contributed to the application of this compensation concept to RHIC at Brookhaven.

  15. Calculation of transition probabilities and ac Stark shifts in two-photon laser transitions of antiprotonic helium

    OpenAIRE

    HORI, MASAKI; Korobov, Vladimir I.

    2010-01-01

    Numerical ab initio variational calculations of the transition probabilities and ac Stark shifts in two-photon transitions of antiprotonic helium atoms driven by two counter-propagating laser beams are presented. We found that sub-Doppler spectroscopy is in principle possible by exciting transitions of the type (n,L)->(n-2,L-2) between antiprotonic states of principal and angular momentum quantum numbers n~L-1~35, first by using highly monochromatic, nanosecond laser beams of intensities 10^4...

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

    Czech Academy of Sciences Publication Activity Database

    Friedman, E.; Gal, A.; Mareš, Jiří

    2005-01-01

    Roč. 761, 3/4 (2005), s. 283-295. ISSN 0375-9474 R&D Projects: GA AV ČR IAA1048305 Institutional research plan: CEZ:AV0Z10480505 Keywords : antiproton-nuclear interaction * RMF calculations * antiproton X-rays Subject RIV: BE - Theoretical Physics Impact factor: 1.950, year: 2005

  17. 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.

  18. Transport from the Recycler Ring to the Antiproton Source Beamlines

    CERN Document Server

    Xiao, M

    2013-01-01

    In the post-Nova era, the protons are directly transported from the Booster ring to the Recycler ring rather than the Main Injector. For Mu2e and g-2 project, the Debuncher ring will be modified into a Delivery ring to deliver the protons to both Mu2e and g-2 experiemnts. Therefore, It requires the transport of protons from the Recycler Ring to the Delivery ring. A new transfer line from the Recycler ring to the P1 beamline will be constructed to transport proton beam from the Recycler Ring to existing Antiproton Source beamlines. This new beamline provides a way to deliver 8 GeV kinetic energy protons from the Booster to the Delivery ring, via the Recycler, using existing beam transport lines, and without the need for new civil construction. This paper presents the Conceptual Design of this new beamline.

  19. 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)

  20. 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)

  1. 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.

  2. Ultralow-energy antiprotons for antihydrogen spectroscopy and antimatter gravity

    International Nuclear Information System (INIS)

    Approximately one million antiprotons have been captured in a large-scale Penning trap at the Low Energy Antiproton Ring (LEAR) at CERN. Up to 65% of the captured antiprotons have subsequently been electron cooled to energies below 1 eV and have been stored up to one hour. This has opened new discussions of the possible use of ultralow-energy antiprotons for gravitational physics, as well as for precision spectroscopy of antihydrogen for CPT tests

  3. Computer control of RF-manipulations in the CERN antiproton accumulator

    International Nuclear Information System (INIS)

    The CERN antiproton accumulator uses a conventional RF system for bunched beam manipulation within the ring. Several different manipulations are needed, often in close succession, so a fast, reliable and accurate method of switching between them is required. This has led to an unconventional computerized beam control system. For a desired set of beam manipulations, the computer calculates the needed voltage and frequency as functions of time, using a mathematical model of the beam and lattice. These are then loaded into function generators which subsequently operate independently of the computer. The RF system, a dual gap, ferrite loaded cavity driven by a 4CX25000 power tetrode, has three main uses: the stacking process to accumulate the antiprotons, the unstacking process to make the accumulated antiprotons available for extraction, and a variety of test and measurement purposes. Two digital function generators control voltage and frequency in the cavity. The voltage function is logarithmic and is fed into an AVC loop which contains a logarithmic detector and modulator to provide high voltage for stacking and low voltage for unstacking. The frequency function controls a 10 to 30 kHz quadrature VCO which is mixed with the output of a quadrature synthesizer producing an 1840 to 1860 kHz frequency range. RF phase and magnet noise were harmful while manipulating low emittance proton and antiproton bunches. A high-pass phase loop acquires beam cavity phase; adding AC corrections to the frequency program eliminated this problem. The cavity tune is maintained by a tuning loop acting on a DC ferrite base. Schematics are provided

  4. The HEAT Cosmic Ray Antiproton Experiment

    Science.gov (United States)

    Nutter, Scott

    1998-10-01

    The HEAT (High Energy Antimatter Telescope) collaboration is constructing a balloon-borne instrument to measure the relative abundance of antiprotons and protons in the cosmic rays to kinetic energies of 30 GeV. The instrument uses a multiple energy loss technique to measure the Lorentz factor of through-going cosmic rays, a magnet spectrometer to measure momentum, and several scintillation counters to determine particle charge and direction (up or down in the atmosphere). The antiproton to proton abundance ratio as a function of energy is a probe of the propagation environment of protons through the galaxy. Existing measurements indicate a higher than expected value at both high and low energies. A confirming measurement could indicate peculiar antiproton sources, such as WIMPs or supersymmetric darkmatter candidates.

  5. Cosmic ray antiprotons from nearby cosmic accelerators

    Science.gov (United States)

    Joshi, Jagdish C.; Gupta, Nayantara

    2015-05-01

    The antiproton flux measured by PAMELA experiment might have originated from Galactic sources of cosmic rays. These antiprotons are expected to be produced in the interactions of cosmic ray protons and nuclei with cold protons. Gamma rays are also produced in similar interactions inside some of the cosmic accelerators. We consider a few nearby supernova remnants observed by Fermi LAT. Many of them are associated with molecular clouds. Gamma rays have been detected from these sources which most likely originate in decay of neutral pions produced in hadronic interactions. The observed gamma ray fluxes from these SNRs are used to find out their contributions to the observed diffuse cosmic ray antiproton flux near the earth.

  6. Calculation of energy deposited and stopping range through deuterium ignition beam and dynamical studies on the energy gain in D-3He mixtures

    OpenAIRE

    Hosseinimotlagh, S. N.; Jahedi, M.; Kianafraz, S.; Ghaderi, Sakineh

    2015-01-01

    The fast ignition approach to ICF consists in first compressing the fuel to high density by a suitable driver and then creating the hot spot required for ignition by means of a second external pulse. If the ignition beam is composed of deuterons, an additional energy is delivered to the target with increased energy gain. Therefore ,in this innovative suggestion ,we consider deuterium  beams for fast ignition in D+3He mixture and solve the dynamical  balance equations under the available  physi...

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

    International Nuclear Information System (INIS)

    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. K-shell ionization by antiprotons

    International Nuclear Information System (INIS)

    We present first calculations for the impact parameter dependence of K-shell ionization rates in anti pCu and in anti pAg collisions at various projectile energies. We show that the effect of the attractive Coulomb potential on the Rutherford trajectory and the anti-binding 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. (orig.)

  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. Cryogenic design of the stochastic cooling pick-ups for the CERN antiproton collector (ACOL)

    International Nuclear Information System (INIS)

    Stochastic cooling, a technique of prime importance for obtaining antiproton beams usable at high-energy colliders, requires wide-band and low-noise signal acquisition and processing. For this purpose, the CERN Antiproton Collector (ACOL), presently under construction, is equipped with six beam pick-up stations operating at cryogenic temperatures. Each station consists of a high-vacuum vessel housing two mobile arrays of pick-up electrodes, cooled to about 100 K by radiation to a surrounding thermal shield, and two preamplifiers kept below 20 K. Refrigeration is provided by a pair of two-stage Gifford-McMahon helium cryogenerators, thermally linked to the preamplifiers and to the thermal shield. The cryogenerators also cool activated charcoal cryopanels, in order to maintain a residual pressure in the vessel below 10-8 mbar. The choice of such cryogenic options is dictated by performance (steady-state and cool-down), simplicity of operation and maintenance, and high reliability

  11. Information on antiprotonic atoms and the nuclear periphery from the PS209 experiment

    OpenAIRE

    Trzcinska, A.; Jastrzebski, J.; Czosnyka, T.; von Egidy, T.; Gulda, K.; Hartmann, F. J.; Iwanicki, J.; Ketzer, B.; Kisielinski, M.; Klos, B.; Kurcewicz, W.; Lubinski, P.; Napiorkowski, P. J.; Pienkowski, L.; Schmidt, R.

    2001-01-01

    In the PS209 experiments at CERN two kinds of measurements were performed: the in-beam measurement of X-rays from antiprotonic atoms and the radiochemical, off-line determination of the yield of annihilation products with mass number A_t -1 (less by 1 than the target mass). Both methods give observables which allows to study the peripheral matter density composition and distribution.

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

    International Nuclear Information System (INIS)

    As part of Fermilab's study of a Very Large Hadron Collider, 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

  13. Antiproton-proton resonant like channels in J/Psi decays into photon, proton and antiproton

    CERN Document Server

    Loiseau, B

    2005-01-01

    The BES collaboration has recently observed a strong enhancement close to the proton-antiproton threshold in the J/Psi decays into photon, proton and antiproton. Such a structure can be explained by a traditional nucleon-antinucleon model. The near threshold 1S0 bound state and/or the well-established 3P0 resonant state found in this nucleon-antinucleon interaction can adequately describe the BES data.

  14. A naturally occurring trap for antiprotons

    International Nuclear Information System (INIS)

    The phenomenon of delayed annihilation of antiprotons in helium is the first instance of a naturally occurring trap for antimatter in ordinary matter. Recent studies of this effect at CERN are summarized, and plans are described for laser excitation experiments to test its interpretation in terms of metastable exotic helium atom formation. (author)

  15. Ionization in antiproton-hydrogen collisions

    International Nuclear Information System (INIS)

    Employing the semiclassical approximation we calculate within the coupled-state formalism the ionization probability in antiproton-hydrogen (anti p+H) collisions. In particular we investigate the adiabatic ionization at the distance of closest approach in almost central collisions. Striking differences in the electron excitation probability compared with proton-hydrogen (p+H) collisions are predicted. (orig.)

  16. Conceptual Design Report. Antiproton - Proton Collider Upgrade 20 GeV Rings. Technical Components and Civil Construction May, 1988

    Energy Technology Data Exchange (ETDEWEB)

    None

    1988-05-01

    This report contains a description of the design and cost estimate of two new 20 GeV rings which will be required to support the upgrade of the Fermilab Collider with a luminosity goal of 5x10 31 cm-2s-1. The new rings include an antiproton post-accumulator, denoted the Antiproton Super Booster (ASB), and a proton post-booster, denoted the Proton Super Booster (PSB). The siting of the rings is shown in Figure I-1. Both rings are capable of operation at 20 GeV, eliminating the need for ever again injecting beam into the Main Ring below transition, and significantly enhancing Main Ring performance. The Antiproton Super Booster is designed to accept and accumulate up to 4x1012 antiprotons from the existing Antiproton Accumulator, and deliver them to the Main Ring at 20 GeV for acceleration and injection into the Collider. It is also designed to accept diluted antiprotons from the Main Ring at 20 GeV for recooling. The PSB accepts 8.9 GeV protons from the existing Booster and accelerates them to 20 GeV for injection into the Main Ring. The PSB is designed to operate at 5 Hz. The siting shown in Figure I-1 has the attractive feature that it removes all Main Ring injection hardware from the AO straight section, opening the possibility of installing a third proton-antiproton interaction region in the Tevatron Collider.

  17. High intensity proton injector for facility of antiproton and ion research

    International Nuclear Information System (INIS)

    The high current ion source with the low energy beam transport (LEBT) will serve as injector into the proton LINAC to provide primary proton beam for the production of antiprotons. The pulsed ion source developed and built in CEA/Saclay operates with a frequency of 2.45 GHz based on ECR plasma production with two coils with 87.5 mT magnetic field necessary for the electron cyclotron resonance. The compact LEBT consists of two solenoids with a maximum magnetic field of 500 mT including two integrated magnetic steerers to adjust the horizontal and vertical beam positions. The total length of the compact LEBT is 2.3 m and was made as short as possible to reduced emittance growth along the beam line. To measure ion beam intensity behind the pentode extraction system, between solenoids and at the end of the beam line, two current transformers and a Faraday cup are installed. To get information about the beam quality and position, the diagnostic chamber with different equipment will be installed between the two solenoids. This article reports the current status of the proton injector for the facility of antiproton and ion research

  18. Experimental test of a new antiproton acceleration scheme in the Fermilab Main Injector

    International Nuclear Information System (INIS)

    In an effort to provide higher intensity and lower emittance antiproton beam to the Tevatron collider for high luminosity operation, a new Main Injector (MI) antiproton acceleration scheme has been developed [1-4]. In this scheme, beam is accelerated from 8 to 27 GeV using the 2.5 MHz rf system and from 27 to 150 GeV using the 53 MHz rf system. This paper reports the experimental results of beam study. Simulation results are reported in a different PAC'05 paper [5]. Experiments are conducted with proton beam from the Booster. Acceleration efficiency, emittance growth and beam harmonic transfer between 2.5 MHz (h=28) and 53 MHz (h=588) buckets have been studied. Beam study shows that one can achieve an overall acceleration efficiency of about 100%, longitudinal emittance growth less than 20% and negligible transverse emittance growth. accelerated to 150 GeV and injected to the Tevatron. The multi-bunch coalescing process is eliminated in this acceleration scheme. Consequently, longitudinal emittance growth is reduced. Smaller emittance growth reduces beam loss

  19. High intensity proton injector for facility of antiproton and ion research

    Energy Technology Data Exchange (ETDEWEB)

    Berezov, R., E-mail: r.berezov@gsi.de; Brodhage, R.; Fils, J.; Hollinger, R.; Ivanova, V. [GSI Helmholtzzentrum für Schwerionenforschung GmbH, Planckstr. 1, 64291 Darmstadt (Germany); Chauvin, N.; Delferriere, O.; Tuske, O. [Commissariat à l’Energie Atomique et aux Energies Alternatives, IRFU, F-91191 Gif-sur-Yvette (France); Ullmann, C. [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)

    2016-02-15

    The high current ion source with the low energy beam transport (LEBT) will serve as injector into the proton LINAC to provide primary proton beam for the production of antiprotons. The pulsed ion source developed and built in CEA/Saclay operates with a frequency of 2.45 GHz based on ECR plasma production with two coils with 87.5 mT magnetic field necessary for the electron cyclotron resonance. The compact LEBT consists of two solenoids with a maximum magnetic field of 500 mT including two integrated magnetic steerers to adjust the horizontal and vertical beam positions. The total length of the compact LEBT is 2.3 m and was made as short as possible to reduced emittance growth along the beam line. To measure ion beam intensity behind the pentode extraction system, between solenoids and at the end of the beam line, two current transformers and a Faraday cup are installed. To get information about the beam quality and position, the diagnostic chamber with different equipment will be installed between the two solenoids. This article reports the current status of the proton injector for the facility of antiproton and ion research.

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

    International Nuclear Information System (INIS)

    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.)

  1. The Angular Distribution Of Electron-positron Pairs From Exclusive Charmonium Decays In Antiproton-proton Annihilations

    CERN Document Server

    McTaggart, R J

    1998-01-01

    The angular distributions of the charmonium resonances J/ Y (3097) and Y (3686) in their exclusive decay to an electron-positron pair are studied. Experiment 835 at the Fermi National Accelerator Laboratory produced charmonium resonances by annihilating protons with antiprotons in the Fixed Target Mode of the Antiproton Accumulator: A stochastically cooled antiproton beam collides with a hydrogen gas jet, which forms clusters under the right pressure and low temperature. The charmonium decay products are detected out of a large hadronic background with the help of a segmented lead glass sampling calorimeter, which is sensitive to the high mass electron-positron charmonium decay, and a set of Cerenkov threshold detectors that provide good electron/pion separation. Several factors influence the angular distribution parameter l taken from the angular distribution, including the energy scale of the resonance, the coupling strength of the charmonium atom, and how quarks and gluons interact in the dissolution...

  2. Study of the anti-hydrogen atom and ion formation in the collisions antiproton-positronium

    International Nuclear Information System (INIS)

    The future CERN experiment called GBAR intends to measure the gravitational acceleration of antimatter on Earth using cold (neV) anti-hydrogen atoms undergoing a free fall. The experiment scheme first needs to cool anti-hydrogen positive ions, obtained thanks to two consecutive reactions occurring when an antiproton beam collides with a dense positronium cloud.The present thesis studies these two reactions in order to optimise the production of the anti-ions. The total cross sections of both reactions have been computed in the framework of a perturbation theory model (Continuum Distorted Wave - Final State), in the range 0 to 30 keV antiproton kinetic energy; several excited states of positronium have been investigated. These cross sections have then been integrated to a simulation of the interaction zone where antiprotons collide with positronium; the aim is to find the optimal experimental parameters for GBAR. The results suggest that the 2P, 3D or, to a lower extend, 1S states of positronium should be used, respectively with 2, less than 1 or 6 keV antiprotons. The importance of using short pulses of antiprotons has been underlined; the positronium will have to be confined in a tube of 20 mm length and 1 mm diameter. In the prospect of exciting the 1S-3D two-photon transition in positronium at 410 nm, a pulsed laser system had already been designed. It consists in the frequency doubling of an 820 nm pulsed titanium-sapphire laser. The last part of the thesis has been dedicated to the realisation of this laser system, which delivers short pulses (9 ns) of 4 mJ energy at 820 nm. (author)

  3. The AFIS experiment: Detecting low energetic antiprotons in a low earth orbit, using an active target detector

    Energy Technology Data Exchange (ETDEWEB)

    Poeschl, Thomas; Gaisbauer, Dominic; Greenwald, Daniel; Hahn, Alexander; Hauptmann, Philipp; Konorov, Igor; Meng, Lingxin; Paul, Stephan [Physics Department E18, Technische Universitaet Muenchen (Germany); Losekamm, Martin [Physics Department E18, Technische Universitaet Muenchen (Germany); Institute of Astronautics, Technische Universitaet Muenchen (Germany); Renker, Dieter [Physics Department E17, Technische Universitaet Muenchen (Germany)

    2014-07-01

    Since the first observation of geomagnetically trapped antiprotons by the PAMELA experiment and the new results on the positron excess by the AMS-02 experiment, the creation and transport of antimatter in the Earth's upper atmosphere attracts more and more attention both at theoretical and experimental side. For this reason the AFIS experiment was initiated to measure the flux of low energetic antiprotons in the South Atlantic Anomaly (SAA). We developed an active target detector made from scintillating fibers connected to silicon photomultipliers which allows to detect antiprotons in the energy interval of about 30 MeV-100 MeV. The stopping curve of incoming antiprotons (Bragg peak) and the signal of outgoing pions created from the annihilation, are used for particle identification as well as triggering. We plan to implement this detector on a 3 unit cubesat satellite in the framework the 'Move2Warp' mission, which is carried out as a student project by the Technische Universitaet Muenchen.

  4. A polarized beam for the M-3 line

    International Nuclear Information System (INIS)

    A beamline is proposed for polarized protons to be built in the M-3 line of the Meson Laboratory utilizing lambda decays. This beamline would provide a clean source of polarized protons or an enriched beam of antiprotons or polarized antiprotons

  5. The TRIUMF stopped π-μ channel

    International Nuclear Information System (INIS)

    The TRIUMF π-μ channel (M9) is described and the measured optical paramters are compared with design values. Measured beam characteristics of pions and muons for several different momenta are reported for protons incident on Be and Cu production targets. A beam of cloud muons at the channel momentum, from π decays near the production target, has been obtained having a high stopping density and small spot size. (auth)

  6. Kickers and power supplies for the Fermilab Tevatron I antiproton source

    International Nuclear Information System (INIS)

    The Fermilab Antiproton Source Accumulator and Debuncher rings require 5 kickers in total. These range in design from conventional ferrite delay line type magnets, with ceramic beam tubes to mechanically complex shuttered kickers situated entirely in the Accumulator Ring's 10-10 torr vacuum. Power supplies are thyratron switched pulse forming networks that produce microsecond width pulses of several kiloamps with less than 30 nanoseconds rise and fall times. Kicker and power supply design requirements for field strength, vacuum, rise and fall time, timing and magnetic shielding of the stacked beam in the accumulator by the eddy current shutter will be discussed. 8 refs., 3 figs., 2 tabs

  7. Radiological considerations for POE-1 photon shutters, collimators and beam stops of the Biomedical Imaging and Therapy beamline at the Canadian Light Source

    Science.gov (United States)

    Asai, Juhachi; Wysokinski, Tomasz W.; Smith, Sheldon; Chapman, Dean

    2008-01-01

    A study of radiation levels due to primary and secondary gas bremsstrahlung is carried out for the BioMedical Imaging and Therapy (BMIT) beamline at the Canadian Light Source (CLS). The BMIT beamline, being built at present, is a major research and diagnostic tool for X-ray imaging and X-ray radiation therapy for animals and humans. For the BMIT beamline to be as flexible as possible, a movable tungsten collimator is designed. This can move vertically and assumes two positions; up and down. The BMIT beamline is, thus, able to perform two modes of operation: one white beam, the other monochromatic. Gas bremsstrahlung produced in the vacuum chamber propagates with synchrotron radiation and may enter the imaging or therapy hutch. In this study, the dose behind the collimator is investigated in each mode by assessing the energy deposition in a water phantom that surrounds the entire copper shutter-tungsten collimator unit. When estimating the dose, particular attention is given to the opening area of the collimator, since this passage leads to the imaging or therapy hutch. Also examined are the doses when a tungsten safety shutter is closed.

  8. Radiological considerations for POE-1 photon shutters, collimators and beam stops of the Biomedical Imaging and Therapy beamline at the Canadian Light Source

    International Nuclear Information System (INIS)

    A study of radiation levels due to primary and secondary gas bremsstrahlung is carried out for the BioMedical Imaging and Therapy (BMIT) beamline at the Canadian Light Source (CLS). The BMIT beamline, being built at present, is a major research and diagnostic tool for X-ray imaging and X-ray radiation therapy for animals and humans. For the BMIT beamline to be as flexible as possible, a movable tungsten collimator is designed. This can move vertically and assumes two positions; up and down. The BMIT beamline is, thus, able to perform two modes of operation: one white beam, the other monochromatic. Gas bremsstrahlung produced in the vacuum chamber propagates with synchrotron radiation and may enter the imaging or therapy hutch. In this study, the dose behind the collimator is investigated in each mode by assessing the energy deposition in a water phantom that surrounds the entire copper shutter-tungsten collimator unit. When estimating the dose, particular attention is given to the opening area of the collimator, since this passage leads to the imaging or therapy hutch. Also examined are the doses when a tungsten safety shutter is closed

  9. Atomic approaches in metastable antiprotonic helium atoms. REPLY to 'analysis of the lifetimes and fractions of antiprotons trapped in metastable antiprotonic-helium states' by I. Shimamura and M. Kimura

    International Nuclear Information System (INIS)

    In the present note the authors clarify the purpose of YO and complement its essential points, thus showing that the criticisms of SK are inappropriate. The paper YO [1] was aimed at discussing some new aspects related to the metastability of hadronic helium atoms which had been discovered when negative kaons [2], negative pions [3] and antiprotons [4] were stopped in liquid helium. The delayed fraction, time spectrum shape and lifetimes were the observables. Further experimental studies are in progress [5], and as of today there is no successful explanation for these interesting phenomena. So, YO tried to give brief and rather qualitative estimates for the observations in an intuitive way, considering only the leading terms. The following problems are discussed in as simple a manner as possible, starting from the exotic-atom viewpoints of Condo [6] and Russell [7]: i)the atomic core polarization effect, ii)the structure and radiative lifetimes, iii)the non-statistical distribution of the angular momentum and an estimate of the delayed fraction, and iv)the isotope effect, though the title represents only i). To respond to the comments of SK, it is important to consider the correspondence between the atomic approach and the molecular approach for the metastable antiprotonic helium atom of Condo-Russell. We therefore begin this note with a discussion of this aspect. (author)

  10. The discovery of geomagnetically trapped cosmic ray antiprotons

    CERN Document Server

    Adriani, O; Bazilevskaya, G A; Bellotti, R; Boezio, M; Bogomolov, E A; Bongi, M; Bonvicini, V; Borisov, S; Bottai, S; Bruno, A; Cafagna, F; Campana, D; Carbone, R; Carlson, P; Casolino, M; Castellini, G; Consiglio, L; De Pascale, M P; De Santis, C; De Simone, N; Di Felice, V; Galper, A M; Gillard, W; Grishantseva, L; Jerse, G; Karelin, A V; Kheymits, M D; Koldashov, S V; Krutkov, S Y; Kvashnin, A N; Leonov, A; Malakhov, V; Marcelli, L; Mayorov, A G; Menn, W; Mikhailov, V V; Mocchiutti, E; Monaco, A; Mori, N; Nikonov, N; Osteria, G; Palma, F; Papini, P; Pearce, M; Picozza, P; Pizzolotto, C; Ricci, M; Ricciarini, S B; Rossetto, L; Sarkar, R; Simon, M; Sparvoli, R; Spillantini, P; Stozhkov, Y I; Vacchi, A; Vannuccini, E; Vasilyev, G; Voronov, S A; Yurkin, Y T; Wu, J; Zampa, G; Zampa, N; Zverev, V G; 10.1088/2041-8205/736/1/L1

    2011-01-01

    The existence of a significant flux of antiprotons confined to Earth's magnetosphere has been considered in several theoretical works. These antiparticles are produced in nuclear interactions of energetic cosmic rays with the terrestrial atmosphere and accumulate in the geomagnetic field at altitudes of several hundred kilometers. A contribution from the decay of albedo antineutrons has been hypothesized in analogy to proton production by neutron decay, which constitutes the main source of trapped protons at energies above some tens of MeV. This Letter reports the discovery of an antiproton radiation belt around the Earth. The trapped antiproton energy spectrum in the South Atlantic Anomaly (SAA) region has been measured by the PAMELA experiment for the kinetic energy range 60--750 MeV. A measurement of the atmospheric sub-cutoff antiproton spectrum outside the radiation belts is also reported. PAMELA data show that the magnetospheric antiproton flux in the SAA exceeds the cosmic-ray antiproton flux by three ...

  11. X-ray transitions from antiprotonic noble gases

    International Nuclear Information System (INIS)

    The onset of antiprotonic X-ray transitions at high principal quantum numbers and the occurrence of electronic X-ray in antiprotonic argon krypton, and xenon is analysed with Multiconfiguration Dirac-Fock calculations. The shell by shell ionisation by Auger electron emission, characterised by appearance and disappearance of X-ray lines, is followed through the antiprotonic cascade by considering transition and binding energies of both the antiproton and remaining electrons. A number of additional lines in the X-ray spectra have been tentatively assigned to electronic transitions caused by electronic de-excitation after Auger emission during the antiprotonic cascade. A few lines remain unexplained so far or are not unambiguously assigned. The complexity of the electronic states cannot be resolved with semiconductor detectors. Hopefully, in future high resolution devices like crystal spectrometers and Auger electron spectroscopy at antiproton at GSI will resolve this complexity

  12. The cosmic ray antiproton background for AMS-02

    International Nuclear Information System (INIS)

    The AMS-02 experiment is measuring the cosmic ray antiproton flux with high precision. The interpretation of the upcoming data requires a thorough understanding of the secondary antiproton background. In this work, we employ newly available data of the NA49 experiment at CERN, in order to recalculate the antiproton source term arising from cosmic ray spallations on the interstellar matter. We systematically account for the production of antiprotons via hyperon decay and discuss the possible impact of isospin effects on antineutron production. A detailed comparison of our calculation with the existing literature as well as with Monte Carlo based evaluations of the antiproton source term is provided. Our most important result is an updated prediction for the secondary antiproton flux which includes a realistic assessment of the particle physics uncertainties at all energies

  13. 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.

  14. Collisions of antiprotons with hydrogen molecular ions

    DEFF Research Database (Denmark)

    Lühr, Armin Christian; Saenz, Alejandro

    2009-01-01

    method are applied in order to describe the target molecule and the collision process. It is shown that three perpendicular orientations of the molecular axis with respect to the trajectory are sufficient to accurately reproduce the ionization cross section calculated by Sakimoto [Phys. Rev. A 71, 062704......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...... (2005)] reducing the numerical effort drastically. The independent-event model is employed to approximate the cross section for double ionization and H+ production in antiproton collisions with H2....

  15. A new approach to experiments with non-relativistic antiprotons

    International Nuclear Information System (INIS)

    Is low-energy antiproton physics phasing out with the present round of experiments or are there good reasons to continue at an improved slow antiproton facility which could be located at a high intensity hadron accelerator? We point out, that there are four frontiers where substantial advances could be made. In particular, we discuss the low-energy frontier and emphasize that experiments with no-relativistic antiprotons would increase drastically the sensitivity and would reveal new effects. (orig.)

  16. Antiproton production in relativistic Si-nucleus collisions

    International Nuclear Information System (INIS)

    We have measured antiproton production cross sections as functions of centrality in collisions of 14.6 GeV/c per nucleon 28Si ions with targets of Al, Cu, and Pb. For all targets, the antiproton yields increase linearly with the number of projectile nucleons that have interacted, and show little target dependence. We discuss the implications of this result on the production and absorption of antiprotons within the nuclear medium

  17. An antiproton catalyst for inertial confinement fusion propulsion

    Science.gov (United States)

    Lewis, Raymond A.; Newton, Richard; Smith, Gerald A.; Toothacker, William S.; Kanzleiter, Randall J.

    1990-01-01

    This paper discusses the concept of an inertial confinement fusion propulsion system involving an antiproton catalyst (for antiproton-induced fission). It is argued that, when the two processes, fusion and antimatter annihilation, are combined into one system, a viable candidate propulsion system for planetary exploration emerges. It is shown that as much as 7.6 GW of power, well within the requrements for interplanetary travel, can be achieved using existing driver technologies and available quantities of antiprotons.

  18. Kaons and antiproton-nucleus scattering

    CERN Document Server

    Haque, S; Rahman, S N

    2003-01-01

    The elastic scattering of Kaons and antiprotons from several nuclei is studied in the framework of the generalized diffraction model due to Frahn and Venter. The systematics of reaction cross section and the standard nuclear radius, as given by the model, are discussed. The parameters obtained from the elastic scattering analyses are used, without any adjustment, to reproduce some inelastic scattering angular distributions and the corresponding deformation parameters are determined.

  19. Measurements of Cosmic Ray Antiprotons with PAMELA

    OpenAIRE

    Wu, Juan

    2010-01-01

    The PAMELA experiment is a satellite-borne apparatus designed to study charged particles, and especially antiparticles, in the cosmic radiation. The apparatus is mounted on the Resurs DK1 satellite which was launched on 15 June 2006. PAMELA has been traveling around the earth along an elliptical and semi-polar orbit for almost five years. It mainly consists of a permanent magnetic spectrometer, a time of flight system and an electromagnetic imaging calorimeter, which allows antiprotons to be ...

  20. Looking for new gravitational forces with antiprotons

    International Nuclear Information System (INIS)

    Quite general arguments based on the principle of equivalence and modern field theory show that it is possible for the gravitational acceleration of antimatter to be different than that for matter. Further, there is no experimental evidence to rule out the possibility. In fact, some evidence indicates there may be unexpected effects. Thus, the planned experiment to measure the gravitational acceleration of antiprotons is of fundamental importance. 20 refs., 3 figs

  1. Kaons and antiproton-nucleus scattering

    International Nuclear Information System (INIS)

    The elastic scattering of Kaons and antiprotons from several nuclei is studied in the framework of the generalized diffraction model due to Frahn and Venter. The systematics of reaction cross section and the standard nuclear radius, as given by the model, are discussed. The parameters obtained from the elastic scattering analyses are used, without any adjustment, to reproduce some inelastic scattering angular distributions and the corresponding deformation parameters are determined. (author)

  2. The Facility for Antiproton and Ion Research

    Science.gov (United States)

    Langanke, K.

    2015-11-01

    In the coming years the Facility for Antiproton and Ion Research FAIR will be constructed at the GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt, Germany. This new accelerator complex will allow for unprecedented and path-breaking research in hadronic, nuclear and atomic physics as well as applied sciences. This manuscript will discuss some of these research opportunities, with a focus on nuclear physics related to supernova dynamics and nucleosynthesis.

  3. 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).

  4. "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 ...

  5. 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 ...

  6. 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 ...

  7. Vaccines Stop Illness

    Science.gov (United States)

    ... page please turn JavaScript on. Feature: Diseases and Vaccinations Vaccines Stop Illness Past Issues / Spring 2015 Table ... if we take away the protection given by vaccination, more and more people will be infected and ...

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

    Science.gov (United States)

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

    2016-06-01

    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.

  9. 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.

  10. Po stopách stop v detektorech stop

    Czech Academy of Sciences Publication Activity Database

    Pachnerová Brabcová, Kateřina; Ambrožová, Iva; Kolísková, Z.

    2012-01-01

    Roč. 20, 1/2 (2012), s. 40-44. ISSN 1210-7085 R&D Projects: GA AV ČR KJB100480901; GA ČR GA205/09/0171; GA ČR GD202/09/H086 Institutional research plan: CEZ:AV0Z10480505 Keywords : beams * dielectric track detectors * geometry Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders

  11. Anti-protons in the primary cosmic radiation

    International Nuclear Information System (INIS)

    A knowledge of the flux of antiprotons is of value in examining the manner in which cosmic rays propagate, assuming, as is conventional, that the antiprotons arise from interactions in the I.S.M. A comparison of observed and expected anti p/p ratios is made. (Auth.)

  12. Experiment to measure the gravitational force on the antiproton

    International Nuclear Information System (INIS)

    A collaboration has been formed to measure the acceleration of antiprotons in the earth's gravitational field. The technique is to produce, decelerate, and trap quantities of antiprotons, to cool them to untralow energy, and to measure their acceleration in a time-of-flight experiment. Present plans and the results of initial efforts toward this end are presented

  13. A study of the reactions antiproton-d→antiproton-dπ+π- and antiproton-d→psub(s)antiproton-pπ- at 14.6 GeV/c and a study of charged multiplicity distributions

    International Nuclear Information System (INIS)

    An analysis of two reactions on deuterium has been performed with incident antiprotons of 14.6 GeV/c: antiproton-d→antiproton-dπ+π- and antiproton-d→psub(s)antiproton-pπ-. The final states are dominated by Δ(1236) resonance production and in the coherent reaction the d* effect is observed as at lower incident momenta. At 14.6 GeV/c, it seems that the diffraction dissociation process as well for the incident particle as for the target takes a large part of the production mechanism for the two reactions. A study of charged multiplicity distributions in antiproton-neutron interactions is presented at 5.5, 9.3 and 14.6 GeV/c. The topological cross sections as well as various statistical moments obtained from the charged multiplicities are studied as functions of the incident momentum. A comparison between our results and antiproton-proton and pp data shows, that in the range of incident momenta used, a scaling function which describes antiproton-N and proton-proton interactions does not exist as expected from the KNO model (Koba-Nielsen-Olesen model)

  14. Physics overview of the Fermilab Low Energy Antiproton Facility Workshop

    International Nuclear Information System (INIS)

    A physics overview is presented of the Fermilab workshop to consider a possible high flux, low energy antiproton facility that would use cooled antiprotons from the accumulator ring of the Tevatron collider. Two examples illustrate the power of each a facility to produce narrow states at high rates. Physics topics to which such a facility may be applied are reviewed

  15. Wave Packet Simulations of Antiproton Scattering on Molecular Hydrogen

    OpenAIRE

    Stegeby, Henrik; Kowalewski, Markus; Piszczatowski, Konrad; Karlsson, Hans O.

    2015-01-01

    The problem of antiproton scattering on the molecular Hydrogen is investigated by means of wave packet dynamics. The electronically potential energy surfaces of the antiproton H2 system are presented within this work. Excitation and dissociation probabilities of the molecular Hydrogen for collision energies in the ultra low energy regime below 10 eV are computed.

  16. Unconventional Purcell filter in superferric magnets in the Facility for Antiproton and Ion Research

    International Nuclear Information System (INIS)

    For the magnets used in beam lines, especially in high resolution applications, the field quality ΔB/B is a very important factor which determines the quality of the beam after passing through the magnets. End-shaping of the poles and introduction of Purcell filters improve field uniformity. However, in most applications, what matters is the uniformity in the total field integrated along the beam path (Δ(∫Bdl)/∫Bdl). With this criterion in mind, we have used unconventional partially penetrating Purcell filters in designing wide aperture highly uniform dipole and quadrupole magnets for the large acceptance low energy beam line in the Super Fragment Separator of the upcoming Facility for Antiproton and Ion Research (FAIR) at Darmstadt. The weight of dipole magnets decreases by the use of such filters

  17. Experimental demonstration of colliding beam lifetime improvement by electron lenses

    Energy Technology Data Exchange (ETDEWEB)

    Shiltsev, Vladimir; Alexahin, Yuri; Kamerdzhiev, Vsevolod; Kuznetsov, Gennady; Zhang, Xiao-Long; /Fermilab; Bishofberger, Kip; /Los Alamos

    2007-10-01

    We report successful application of space-charge forces of a low-energy electron beam for improvement of particle lifetime determined by beam-beam interaction in high-energy collider. In our experiments, an electron lens, a novel instrument developed for the beam-beam compensation, was set on a 980-GeV proton bunch in the Tevatron proton-antiproton collider. The proton bunch losses due to its interaction with antiproton beam were reduced by a factor of 2 when the electron lens was operating. We describe the principle of electron lens operation and present experimental results.

  18. 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.

  19. Antiproton cloud compression in the ALPHA apparatus at CERN

    International Nuclear Information System (INIS)

    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

  20. 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.

  1. 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.

  2. 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.

  3. Antiproton production in heavy-ion collisions at energies below the threshold

    International Nuclear Information System (INIS)

    In the framework of this thesis the antiproton production in heavy ion collisions at projectile energies far below the threshold for anti p production in nucleon-nucleon collisions (5.63 GeV/u) was studied. A suited detection apparature was developed and constructed at the fragment separator-magnet spectrometer at the Society for Heavy Ion Research (GSI). For the identification of the antiprotons the momentum of the particles emitted in beam direction was measured and their velocity multiple-redundantly determined by means of time-of-flight measurements and threshold Cherenkov detectors. By this way the antiprotons could be in spite of low anti p production cross sections and high production rates for lighter particles (R antip:RK--:Rπ--∼1:5*103:107) background-freely determined. By this experiment for Ne+NaF, Cu, Sn, and Bi as well ass Ni+Ni collisions at incident energies between 1.6 GeV/u and 2.0 GeV/u production cross sections for antiprotons in the momentum range between 1.0 GeV/c and 2.2 GeV/c and for kaons and pions between 0.5 GeV/c and 2.8 GeV/c were measured, in order to study the influence of collisional-system size, incident energy, and secondary-particle momentum on the production probabilities and to contribute in comparison with the prognoses of theoretical models to the explanation of the particle production mechanisms. (HSI)

  4. Laser-Beam Separator

    Science.gov (United States)

    Mcdermid, I. S.

    1984-01-01

    Train of prisms and optical stop separate fundamental beam of laser from second and higher order harmonics of beam produced in certain crystals and by stimulated Raman scattering in gases and liquids.

  5. Collimation with hollow electron beams

    CERN Document Server

    Stancari, G; Annala, G; Kuznetsov, G; Shiltsev, V; Still, D A; Vorobiev, L G

    2011-01-01

    A novel concept of controlled halo removal for intense high-energy beams in storage rings and colliders is presented. It is based on the interaction of the circulating beam with a 5-keV, magnetically confined, pulsed hollow electron beam in a 2-m-long section of the ring. The electrons enclose the circulating beam, kicking halo particles transversely and leaving the beam core unperturbed. By acting as a tunable diffusion enhancer and not as a hard aperture limitation, the hollow electron beam collimator extends conventional collimation systems beyond the intensity limits imposed by tolerable losses. The concept was tested experimentally at the Fermilab Tevatron proton-antiproton collider. The first results on the collimation of 980-GeV antiprotons are presented.

  6. Progress with Tevatron Electron Lens Head-On Beam-Beam Compensation

    International Nuclear Information System (INIS)

    Tevatron electron lenses have been successfully used to mitigate bunch-to-bunch differences caused by longrange beam-beam interactions. For this purpose, the electron beam with uniform transverse density distribution was used. Another planned application of the electron lens is the suppression of tune spread due to head-on beam-beam collisions. For this purpose, the transverse distribution of the E- beam must be matched to that of the antiproton beam. In 2009, the Gaussian profile electron gun was installed in one of the Tevatron electron lenses. We report on the first experiments with non-linear beam-beam compensation. Discussed topics include measurement and control of the betatron tune spread, importance of the beam alignment and stability, and effect of electron lens on the antiproton beam lifetime.

  7. Elastic and inelastic scattering of 30 MeV and 180 MeV antiprotons on nuclei

    International Nuclear Information System (INIS)

    This thesis reports on the first measurements of angular distributions for elastic and inelastic scattering of antiprotons from nuclei, which have been performed, using the beam delivered by LEAR and the spectrometer SPES II, over a wide angular range and with good precision. Angular distributions for elastic scattering of 50 MeV antiprotons from 12C, 40Ca, 208Pb and 180 MeV antiprotons from 12C, 16O, 18O, 40Ca, 208Pb have been measured. Data on the inelastic 4.4 MeV and 9.6 MeV excited states of 12C and 1.98 MeV excited state of 18O have also been collected. The diffractive angular distributions are first analysed in terms of a fuzzy black disk model, which confirms that the antiproton is strongly absorbed (annihilation) by the nuclei. Optical model analysis, with Woods-Saxon geometry, shows that the real potential is attractive and shallow. The potentials are only determined at the nuclear surface, around the strong absorption radius, where /W(R)/ > 2 /V(R)/. Main characteristics of the antip-nucleus elastic scattering cross sections are well described within microscopic models using the free elementary antiN N interaction, like KMT which have no free parameters. Possibility for test of spin-isospin dependence of the elementary amplitude antiN-N from the measurement of unnatural parity states is also studied

  8. LEAP [Low-Energy Antiproton]: A balloon-borne search for low-energy cosmic-ray antiprotons

    International Nuclear Information System (INIS)

    The LEAP (Low-Energy Antiproton) experiment is a search for cosmic-ray antiprotons in the 120 MeV to 1.2 GeV kinetic energy range. The motivation for this project was the result announced by Buffington et. al. (1981) that indicated an anomalously high antiproton flux below 300 MeV; this result has compelled theorists to propose sources of primary antiprotons above the small secondary antiproton flux produced by high energy cosmic-ray collisions with nuclei in the interstellar medium. LEAP consisted of the NMSU magnetic spectrometer, a time-of-flight system designed at Goddard Space Flight Center, two scintillation detectors, and a Cherenkov counter designed and built at the University of Arizona. Analysis of flight data performed by the high-energy astrophysics group at Goddard Space Flight Center revealed no antiproton candidates found in the 120 MeV to 360 MeV range; 3 possible antiproton candidate events were found in the 500 MeV to 1.2 GeV range in an analysis done here at the University of Arizona. However, since it will be necessary to sharpen the calibration on all of the LEAP systems in order to positively identify these events as antiprotons, only an upper limit has been determined at present. Thus, combining the analyses performed at the University of Arizona and Goddard Space Flight Center, 90% confidence upper limits of 3.5 x 10-5 in the 120 MeV to 360 MeV range and 2.3 x 10-4 in the 500 MeV to 1.2 GeV range for the antiproton/proton ratio is indicated by the LEAP results. LEAP disagrees sharply with the results of the Buffington group, indicating a low antiproton flux at these energies

  9. Antiproton-proton annihilations into four prongs at 7.2 GeV/c

    International Nuclear Information System (INIS)

    Annihilation reactions are described in which four charged pions and also maybe uncharged particles are produced. Data was acquired in an antiproton-proton experiment at a beam momentum of 7.2 GeV/c and 220K pictures of the CERN 2m HBC were measured. Cross sections have been determined and angular distributions of the pions and of some resonances are given. Two models that describe annihilation reactions are treated, the so called CLA model and a simple quark model. (C.F./Auth.)

  10. 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.

  11. 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)

  12. FNAL main ring to energy save antiproton transfer system for Tevatron I

    International Nuclear Information System (INIS)

    A system for antiproton beam transfer from the Main Ring to the Energy Saver for colliding beam operations has been designed and fabricated. The system is similar to the existing proton beam transfer system used for fixed target operation of the Energy Saver. Using a fast kicker in the Main Ring, one or several bunches of 150 GeV pbars will be kicked horizontally across the septa of two Lambertsons into a short transfer line. At the end of this line, they are injected into the Energy Saver through two more Lambertsons and kicked onto a closed orbit by a second fast kicker. For commissioning and tune-up, the system will be operated in reverse, extracting 150 GeV protons from the Energy Saver to the Main Ring. In addition to a description of the design of the system and its components, the status of the installation and commissioning will also be discussed

  13. Feasibility study of a decelerating radio frequency quadrupole system for the antiproton decelerator AD

    CERN Document Server

    Bosser, Jacques; Brouet, M; Couturier, B; Gelato, G; Giovannozzi, Massimo; Grandclaude, F; Hémery, J Y; Lombardi, A M; Mikkelsen, U; Maury, S; Möhl, D; Pedersen, F; Pirkl, Werner; Raich, U; Umstätter, H H; Vretenar, Maurizio

    1998-01-01

    This feasibility study reports on a decelerating Radio-Frequency Quadrupole (RFQ) system for post-deceleration of the 100 MeV/c antiproton beam of the AD machine. The corresponding kinetic energy of 5.314 MeV is reduced to values which can be chosen between 10 to 100 keV with minimal blow-up of the normalised beam emittances. This wide range of output energy is required for the second phase of the ASACUSA experiment; it is achieved by electrostatic means. The study gives details of the overall performance of the system, the proposed implementation of the RFQ, the associated rf equipment, the beam lines, the diagnostics as well as estimations for the cost and the manpower requirements of the project.

  14. Search for narrow lines in photon spectra from proton-antiproton annihilations at rest

    International Nuclear Information System (INIS)

    Inclusive photon spectra from annihilation of antiprotons stopped in a liquid hydrogen target were measured at LEAR (CERN) with a magnetic pair spectrometer. The FWHM energy resolution of the spectrometer in the region from 100-700 MeV was in the range from 2 to 4.5%. A total number of about 4.8.106 events with energies up to 1 GeV have been reconstructed. The photon spectra were scanned for possible lines with widths comparable to spectrometer resolution indicating the existence of bound nucleon-antinucleon states. No such structures were found with branching ratios greater than 4 to 8.10-4 at 95% confidence level. Results of former experiments could not be confirmed. (orig.)

  15. Should Exam Be Stopped?

    Institute of Scientific and Technical Information of China (English)

    邢连香

    2006-01-01

    The exam system has come to be the main topic of modern education.As it plays so important a role in the area of education that it is under much discussion as to its use.People who are for it try to develop this system more;those who are against it believe that such a system should be stopped.Should exam be stopped?In my opinion it should be.Firstly,a number of people think that an exam is the only way to test knowledge,but,in fact,that is not true.A few questions given in an exam could in no way cover the ...

  16. The stop on top

    CERN Document Server

    Zakareishvili, Tamar

    2016-01-01

    Supersymmetric partners of the top quark have been sought since the top quark has been discovered at the Tevatron. The searches are more easily performed in scenarios where the mass splitting between the top and the stop is large and where differences in kinematics are striking. The region in which top and stop are almost degenerate in mass is more difficult to explore experimentally as the final state kinematics are very similar, apart from angular-related distributions which reflect the spin/parity difference between the two particles. Usually the searches are performed looking for deviations on the measured top-quark pair production cross section with respect to the standard model prediction, or looking to simple variables such as the difference in the azimuthal angle between two leptons produced after top quark decays.

  17. Investigation of RADTRAN Stop Model input parameters for truck stops

    International Nuclear Information System (INIS)

    RADTRAN is a computer code for estimating the risks and consequences as transport of radioactive materials (RAM). RADTRAN was developed and is maintained by Sandia National Laboratories for the US Department of Energy (DOE). For incident-free transportation, the dose to persons exposed while the shipment is stopped is frequently a major percentage of the overall dose. This dose is referred to as Stop Dose and is calculated by the Stop Model. Because stop dose is a significant portion of the overall dose associated with RAM transport, the values used as input for the Stop Model are important. Therefore, an investigation of typical values for RADTRAN Stop Parameters for truck stops was performed. The resulting data from these investigations were analyzed to provide mean values, standard deviations, and histograms. Hence, the mean values can be used when an analyst does not have a basis for selecting other input values for the Stop Model. In addition, the histograms and their characteristics can be used to guide statistical sampling techniques to measure sensitivity of the RADTRAN calculated Stop Dose to the uncertainties in the stop model input parameters. This paper discusses the details and presents the results of the investigation of stop model input parameters at truck stops

  18. 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 ...

  19. Experimental demonstration of beam-beam compensation by Tevatron electron lenses and prospects for the LHC

    Energy Technology Data Exchange (ETDEWEB)

    Shiltsev, V.; Alexahin, Y.; Kamerdzhiev, V.; Kuznetsov, G.; Zhang, X.L.; /Fermilab; Bishofberger, K.; /Los Alamos

    2007-06-01

    Electromagnetic long-range and head-on interactions of high intensity proton and antiproton beams are significant sources of beam loss and lifetime limitations in the Tevatron Collider Run II (2001-present). We present observations of the beam-beam phenomena in the Tevatron and results of relevant beam studies. We analyze the data and various methods employed in high energy physics (HEP) operation, predict the performance for planned luminosity upgrades and discuss ways to improve it.

  20. Design of a new low momentum kaon beam for the AGS

    International Nuclear Information System (INIS)

    The low momentum beam described is to be a unique source of antiprotons as well as kaons. The discussion covers (1) choice of production angle; (2) secondary beams; (3) the use of sector dipole magnets for minimizing aberrations; (4) beam bending magnets; (5) beam separators; and (6) beam acceptance

  1. Antiproton cell experiment: antimatter is a better killer

    CERN Document Server

    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)

  2. Do positrons and antiprotons respect the weak equivalence principle?

    International Nuclear Information System (INIS)

    We resolve the difficulties which Morrison identified with energy conservation and the gravitational red-shift when particles of antimatter, such as the positron and antiproton, do not respect the weak equivalence principle. 13 refs

  3. 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...

  4. Rescattering effects in antiproton deuteron annihilation at intermediate energies

    International Nuclear Information System (INIS)

    In this paper higher order corrections to the single scattering term for antiproton deuteron annihilation are evaluated. As dominant corrections the initial state interaction of the antiprotons and the rescattering of pions are considered. For low spectator momenta, these corrections cause a strong modulation of the distribution in the invariant mass of the annihilation pions, which could modify the parameters of the resonant baryonium states

  5. Cosmic Antiproton Constraints on Effective Interactions of the Dark Matter

    CERN Document Server

    Cheung, Kingman; Yuan, Tzu-Chiang

    2010-01-01

    Using an effective interaction approach to describe the interactions between the dark matter particle and the light degrees of freedom of the standard model, we calculate the antiproton flux due to the annihilation of the dark matter in the Galactic Halo and compare to the most recent antiproton spectrum of the PAMELA experiment. We obtain useful constraints on the size of the effective interactions that are comparable to those deduced from collider and gamma-ray experiments.

  6. Cosmic antiproton constraints on effective interactions of the dark matter

    Energy Technology Data Exchange (ETDEWEB)

    Cheung, Kingman [Division of Quantum Phases and Devices, School of Physics, Konkuk university, Seoul 143-701 (Korea, Republic of); Tseng, Po-Yan [Department of Physics, National Tsing Hua University, Hsinchu 300, Taiwan (China); Yuan, Tzu-Chiang, E-mail: cheung@phys.nthu.edu.tw, E-mail: tcyuan@phys.sinica.edu.tw, E-mail: d9722809@oz.nthu.edu.tw [Institute of Physics, Academia Sinica, Nankang, Taipei 11529, Taiwan (China)

    2011-01-01

    Using an effective interaction approach to describe the interactions between the dark matter particle and the light degrees of freedom of the standard model, we calculate the antiproton flux due to the annihilation of the dark matter in the Galactic Halo and compare to the most recent antiproton spectrum of the PAMELA experiment. We obtain useful constraints on the size of the effective interactions that are comparable to those deduced from collider and gamma-ray experiments.

  7. Cosmic antiproton constraints on effective interactions of the dark matter

    International Nuclear Information System (INIS)

    Using an effective interaction approach to describe the interactions between the dark matter particle and the light degrees of freedom of the standard model, we calculate the antiproton flux due to the annihilation of the dark matter in the Galactic Halo and compare to the most recent antiproton spectrum of the PAMELA experiment. We obtain useful constraints on the size of the effective interactions that are comparable to those deduced from collider and gamma-ray experiments

  8. Stopping power of two-dimensional spin quantum electron gases

    Science.gov (United States)

    Zhang, Ya; Jiang, Wei; Yi, Lin

    2015-04-01

    Quantum effects can contribute significantly to the electronic stopping powers in the interactions between the fast moving beams and the degenerate electron gases. From the Pauli equation, the spin quantum hydrodynamic (SQHD) model is derived and used to calculate the stopping power and the induced electron density for protons moving above a two-dimensional (2D) electron gas with considering spin effect under an external in-plane magnetic field. In our calculation, the stopping power is not only modulated by the spin direction, but also varied with the strength of the spin effect. It is demonstrated that the spin effect can obviously enhance or reduce the stopping power of a 2D electron gas within a laboratory magnetic field condition (several tens of Tesla), thus a negative stopping power appears at some specific proton velocity, which implies the protons drain energy from the Pauli gas, showing another significant example of the low-dimensional physics.

  9. Stopping power of two-dimensional spin quantum electron gases

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Ya [School of Physics, Huazhong University of Science and Technology, Wuhan 430074 (China); Jiang, Wei, E-mail: weijiang@hust.edu.cn [School of Physics, Huazhong University of Science and Technology, Wuhan 430074 (China); Centre for mathematical Plasma-Astrophysics, Department of Mathematics, Katholieke Universiteit Leuven, B-3001 Leuven (Belgium); Yi, Lin [School of Physics, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2015-04-15

    Quantum effects can contribute significantly to the electronic stopping powers in the interactions between the fast moving beams and the degenerate electron gases. From the Pauli equation, the spin quantum hydrodynamic (SQHD) model is derived and used to calculate the stopping power and the induced electron density for protons moving above a two-dimensional (2D) electron gas with considering spin effect under an external in-plane magnetic field. In our calculation, the stopping power is not only modulated by the spin direction, but also varied with the strength of the spin effect. It is demonstrated that the spin effect can obviously enhance or reduce the stopping power of a 2D electron gas within a laboratory magnetic field condition (several tens of Tesla), thus a negative stopping power appears at some specific proton velocity, which implies the protons drain energy from the Pauli gas, showing another significant example of the low-dimensional physics.

  10. Measurement of Spin Transfer Observables in Antiproton-Proton -> Antilambda-Lambda at 1.637 GeV/c

    CERN Document Server

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

    2002-01-01

    Spin transfer observables for the strangeness-production reaction Antiproton-Proton -> Antilambda-Lambda have been measured by the PS185 collaboration using a transversely-polarized frozen-spin target with an antiproton beam momentum of 1.637 GeV/c at the Low Energy Antiproton Ring at CERN. This measurement investigates observables for which current models of the reaction near threshold make significantly differing predictions. Those models are in good agreement with existing measurements performed with unpolarized particles in the initial state. Theoretical attention has focused on the fact that these models produce conflicting predictions for the spin-transfer observables D_{nn} and K_{nn}, which are measurable only with polarized target or beam. Results presented here for D_{nn} and K_{nn} are found to be in disagreement with predictions from existing models. These results also underscore the importance of singlet-state production at backward angles, while current models predict complete or near-complete t...

  11. The Brain Never Stops

    OpenAIRE

    Sadaghiani, Sepideh

    2014-01-01

    Your brain is doing a lot of work when you are engaged in activities such as sports, playing a game, or watching a movie. Your brain is also a master of associating one thought with another and making your mind wander. But what does your brain do when you are not engaged in particular thoughts or actions? Interestingly, similar to the heart that always keeps beating, the brain never stops its activity. For example, your brain is highly active even when you are fast asleep. In fact, brain cell...

  12. Gentlemen, stop your engines!

    OpenAIRE

    Haworth, Guy McCrossan

    2007-01-01

    For fifty years, computer chess has pursued an original goal of Artificial Intelligence, to produce a chess-engine to compete at the highest level. The goal has arguably been achieved, but that success has made it harder to answer questions about the relative playing strengths of man and machine. The proposal here is to approach such questions in a counter-intuitive way, handicapping or stopping-down chess engines so that they play less well. The intrinsic lack of man-machine games may be ...

  13. A recoil detector for the measurement of antiproton-proton elastic scattering at angles close to 90

    International Nuclear Information System (INIS)

    The design and construction of a recoil detector for the measurement of recoil protons of antiproton-proton elastic scattering at scattering angles close to 90 circle are described. The performance of the recoil detector has been tested in the laboratory with radioactive sources and at COSY with proton beams by measuring proton-proton elastic scattering. The results of laboratory tests and commissioning with beam are presented. Excellent energy resolution and proper working performance of the recoil detector validate the conceptual design of the KOALA experiment at HESR to provide the cross section data needed to achieve a precise luminosity determination at the PANDA experiment. (orig.)

  14. Study of hyperon-antihyperon production in antiproton-proton collision at 4 GeV/c

    International Nuclear Information System (INIS)

    We present the results on hyperon-antihyperon production by 4 GeV/c antiprotons in hydrogen. We used about 105 pictures taken in an antiproton beam from the CERN proton synchrotron with the 81 cm Saclay hydrogen bubble chamber. The aim of this work was the study, through the cross sections and the angular distributions, of production mechanism of hyperon antihyperon pairs and excited hyperons (or antihyperons). For most of the channels, these angular distributions show a strong forward peaking of the antihyperon in the center of mass of the interaction. This suggests that a peripheral-type mechanism is predominant in these processes. We compare the results of some cross sections, with theoretical predictions according to SU3 unitary symmetry. (author)

  15. 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 ...

  16. CERN: LEP delivers; Looking deeper at spin; Handling low energy antiprotons

    International Nuclear Information System (INIS)

    One year ago, with the world catalogue of Z particles - the electrically neutral carrier of the weak nuclear force - containing a few hundred examples, it sounded extravagant when proponents of CERN's new LEP electron-positron collider promised a hundred thousand Zs by Christmas 1989. The first round of experiments in the North Area of CERN's SPS proton synchrotron included a considerable investment in studies using high energy muon beams. This paid off with important contribuions to physics, particularly in the measurement of the quark/gluon content (structure functions) of nucleons. ; The LEAR low energy antiproton ring at CERN takes its antimatter beams down to very low kinetic energies - less than 10 MeV - for a unique range of physics studies. However even these modest energies are too high for a series of experiments aiming to explore the effects of gravity on antimatter

  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. Implications of different stopping power models on target heating simulations using HYDRA

    Science.gov (United States)

    Veitzer, Seth; Stoltz, Peter; Barnard, John; Henestroza, Enrique; Kerbel, Gary; Marinak, Marty

    2007-11-01

    Accurate numerical simulations of ion driven Warm Dense Matter experiments requires accurate models of stopping powers for targets with temperatures up to a few eV. For finite temperature targets, energy loss of beam ions is comprised of contributions from nuclear stopping, bound electron stopping, and free electron stopping. We compare two different stopping power algorithms and the implications on target heating for two different beams corresponding to the current Neutralized Drift Compression Experiment (NDCX) and proposed NDCX II experiments. The NDCX I beam has a beam energy much lower than the Bragg peak while the NDCX II beam is designed to enter the target just above the Bragg peak, and exit just below. The first stopping power algorithm is based on the classical Bethe-Bloch formulation as is currently implemented in the HYDRA simulation code. The second algorithm is based on rescaling of experimental protonic stopping powers as developed by Brandt and Kitagawa for nuclear and bound electronic stopping, and free electron stopping following the model developed by Peter and Meyer-ter-Vehn.

  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. Stop the RIKA BANARE

    Science.gov (United States)

    Watanabe, Yoshio

    Children who want to study science & technology are decreasing continuously in Japan. This phenomenon is so called “Rika Banare” meaning literally science apart. Then, the number of students aiming at being engineers is decreasing. This will be a threat for Japanese industry. Many science & technology events are being held everywhere in Japan to overcome Rika Banare. However, most of them leave no sustainable influence over the students who reach to high school age. The reason why Rika Banare takes place is discussed. Then, it is insisted that the promotion of the attractive features of engineering career is important as well as improvement of the education system. In this article, eight proposals to stop Rika Banare are presented. Five of them are related to education system and the rest three to the improvement of social status of engineers.

  1. Current stopping power analyses

    International Nuclear Information System (INIS)

    Modified Bethe-Bloch stopping power theory permits fairly accurate calculation of energy losses over a broad interval of projectile velocity v = νc insofar as several parameters appearing in the revised Bethe-Bloch formula have been corectly evaluated. Since the parameters cannot in general be ascertained by calculation from first principles, fits of theory to measurement remain the best method of evaluation. The parameters alluded to are: the target mean excitation energy; the shell correction scaling parameters; the composite single free parameter of the Barkas (projectile-z3) effect correction formalism, and the strength of the correction term; the high velocity density effect correction parameter; and the low velocity charge state parameter. These parameters are discussed

  2. Binary theory of electronic stopping

    CERN Document Server

    Sigmund, P

    2002-01-01

    Binary stopping theory has been developed to characterize the electronic stopping of swift heavy ions in matter. It is an extension of Bohr's classical theory of 1913 incorporating screening, higher-order-Z sub 1 and shell corrections, high-speed quantum and relativity corrections as well as projectile excitation and ionization. The main numerical input comes from optical properties. The computation of shell corrections involves orbital velocity distributions of target and projectile electrons. Calculated stopping parameters depend on ion charge. Equilibrium stopping forces may be computed by adoption of a suitable model for the equilibrium charge state. This paper summarizes the current status of the theory, in particular the sensitivity of its predictions to pertinent input. Charge-dependent stopping forces have been calculated for selected systems and compared to experimental results. Equilibrium stopping forces calculated for a wide variety of ion-target combinations are compared with experimental data fr...

  3. Antiproton-impact ionization of H2

    International Nuclear Information System (INIS)

    Ionization processes in antiproton collisions with H2 are studied by direct solution of the time-dependent Schroedinger equation. A time-dependent close-coupling method based on an expansion of a one-electron 3D wavefunction in the field of H+2 is used to calculate single-ionization cross sections at incident energies ranging from 50 keV to 1.5 MeV. Averaging over the molecular orientations, the single-ionization cross sections are in reasonable agreement with time-dependent basis set calculations and experiment. A time-dependent close-coupling method based on an expansion of a two-electron 6D wavefunction in the field of H2+2 is used to calculate single- and double-ionization cross sections at an incident energy of 100 keV. Initiatory 6D results for the H+2 production cross section range are somewhat lower than experiment, while the H+ production cross section range brackets experiment.

  4. Elastic and inelastic scattering of antiprotons

    International Nuclear Information System (INIS)

    During the last two years very interesting results have been collected at LEAR on both the elementary pantip and the antip nucleus interactions. A review of all the interesting experimental results already available is far beyond the scope of the present talk. Its topic will be essentially limited to report on the new experimental informations dealing with the knowledge of the fundamental properties of the antip p elementary interaction and the determination of the characteristics of the antip nucleus interaction. The results of the antip p cross sections measured at low momenta by the PS173 and PS172 experiments are discussed. The antip nucleus elastic scattering angular distributions collected by the PS184 experiment have significantly contributed to define the properties of the p nucleus optical potential and stimulated a lot of microscopic calculations. The results are reviewed. A comparison to the informations obtained from the measurements of X-rays in antiprotonic atoms done by the PS176 and PS186 experiments is given. The interpretation of the inelastic scattering data measured for the 12C(antip, antip)12C* system at 47 and 180 MeV for various discrete states is presented: special emphasis will be given to the study of spin-flip transitions to unnatural parity states which would provide significant constant on the isovector tensor component of the NantiN interaction. Status on the experimental study of the (antip, p) reaction is discussed

  5. Delayed annihilation of antiprotons in helium gas

    International Nuclear Information System (INIS)

    The delayed annihilation of antiprotons, which was recently discovered in liquid 4He at KEK, has been studied at CERN in gas-phase 4He and 3He. The annihilation time spectra in gas 4He at various pressures were found to be similar to that for liquid 4He. The observed average lifetime in the region t > 1μsec for 3 atm 4He was about 3.2μsec, while for 3 atm 3He gas it was 2.8μsec, i.e. shorter by 15 %. The time spectra show a growth-decay type function, which is indicative of the presence of a series of metastable states. For 4He and 3He they have nearly identical shapes, differing only in the time scale by 14 ± 3 %. These observations are qualitatively consistent with the atomic model of p-bare-He++ proposed by Condo. The time spectra were found to be sensitive to the presence of small amounts (as small as 20 ppm) of H2. No evidence was seen for delayed annihilation in gaseous Ne. 36.10. (author)

  6. Charm production in antiproton-proton annihilation

    CERN Document Server

    Haidenbauer, J

    2010-01-01

    We study the production of charmed mesons (D) and baryons (Lambda_c) in antiproton-proton (app) annihilation close to their respective production thresholds. The elementary charm production process is described by either baryon/meson exchange or by quark/gluon dynamics. Effects of the interactions in the initial and final states are taken into account rigorously. The calculations are performed in close analogy to our earlier study on app -> antiLambda-Lambda and app -> antiK-K by connecting the processes via SU(4) flavor symmetry. Our predictions for the antiLambda_c-Lambda_c production cross section are in the order of 1 to 7 mb, i.e. a factor of around 10-70 smaller than the corresponding cross sections for antiLambda-Lambda However, they are 100 to 1000 times larger than predictions of other model calculations in the literature. On the other hand, the resulting cross sections for antiD-D production are found to be in the order of 10^{-2} -- 10^{-1} microbarn and they turned out to be comparable to those ob...

  7. Stopping powers for heavy ions

    International Nuclear Information System (INIS)

    This report re-examines the prospects for a general heavy-ion stopping power table in the light of new experimental stopping power measurements. The question of oscillations in the dependence of the stopping powers on both the projectile, Z1, and the material, Z2, is examined. We can find no evidence for higher order corrections such as the Z13-effect. (author)

  8. Spin Filtering of Stored (Anti)Protons: from FILTEX to COSY to AD to FAIR

    International Nuclear Information System (INIS)

    We review the theory of spin filtering of stored (anti)protons by multiple passage through the polarized internal target (PIT). Implications for the antiproton polarization buildup in the proposed PAX experiment at FAIR GSI are discussed

  9. Medium-Energy Antiproton Physics with the Antiproton Annihilation Spectrometer (TApAS*) at Fermilab

    Energy Technology Data Exchange (ETDEWEB)

    Bartoszek, Larry; /Bartoszek Engineering, Aurora; Piacentino, Giovanni M.; /Cassino U.; Phillips, Thomas J.; /Duke U.; Apollinari, Giorgio; Broemmelsiek, Daniel R.; Brown, Charles N.; Christian, David C.; Derwent, Paul; Gollwitzer, Keith; Hahn, Alan; Papadimitriou, Vaia; /Fermilab /INFN, Pisa /Hbar Technologies, West Chicago /Houston U. /IIT, Chicago /IIT, Hyderabad /ITEP /KyungPook National U. /LPI

    2008-01-01

    We propose to assemble a cost-effective, yet powerful, solenoidal magnetic spectrometer for antiproton-annihilation events and use it at the Fermilab Antiproton Accumulator to measure the charm production cross section, study rare hyperon decays, search for hyperon CP asymmetry, and precisely measure the properties of several charmonium and nearby states. 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 experiment will be carried out by an international collaboration, with installation occurring during the accelerator downtime following the completion of the Tevatron run, and with funding largely from university research grants. The experiment 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.

  10. Feasibility of an antiproton catalyzed fission fragment rocket

    Science.gov (United States)

    Hidinger, David S.

    1992-03-01

    The purpose of this project was to investigate the feasibility of an antiproton catalyzed fission fragment rocket (FFR). The FFR is characterized by the extraction of fission fragments from the fuel, and the utilization of their kinetic energy for thrust generation. A significant drawback to previous FFR designs was the required critical nuclear pile as the fission fragment source. The author examined the possibility of replacing the critical pile with a sub-critical pile driven by antiprotons. Recent experiments have revealed that antiprotons stimulate highly energetic fissions in 238U, with a neutron multiplicity of 13.7 neutrons per fissions. This interaction was used as a throttled neutron source. The pile consisted of layers of fissile coated fibers which are designed to allow fission fragments to escape them, where the fragments collide with a fluid. The heated fluid is then ejected from the rocket to provide thrust. The calculations performed indicate that each antiproton injected into the pile can stimulate 8 or more fissions while maintaining a neutron multiplication of less than 0.4. Based on the results, the specific design presented was inadequate. Despite this, the concept of using the antiproton-U interaction as a source of thrust warrants further study.

  11. Laser spectroscopy of antiprotonic helium and pionic helium

    International Nuclear Information System (INIS)

    ASACUSA (Atomic Spectroscopy and Collisions Using Slow Antiproton) experiment of CERN has observed two-photon spectroscopy by making non-linear transitions of the antiprotons which have occupied highly excited levels. The metastable antiproton helium atoms are studied by irradiating two laser light photons propagating in the counter direction. As the result, the spectrum of narrow line width was observed by making the Doppler width of the resonant transition to decrease. And the anti-proton helium transition frequency was measured with the accuracy of (2.3∼5) X10-9. The mass ratio of the antiproton and the electron has been decided to be Mp/me =1836.152674(23) from the comparison of quantum electrodynamics calculation and the present experimental result. The pion-Helium experiment instrument has been also constructed at the ring cyclotron of PSI (Paul Sherer Institute) toward the successful laser spectroscopy of this atom. When this atom is observed, the π- mass can be obtained with the accuracy higher than 6∼8 orders of magnitude which may contribute to the direct measurement of the upper limit value of muon neutrino mass in the Particle Data Book Mass although various difficulties may be encountered. This report describes briefly the laser spectroscopy at first and then the recent situation of the experiments. (S. Funahashi)

  12. Ultra-low energy antiprotons for anti hydrogen spectroscopy and antimatter gravity

    International Nuclear Information System (INIS)

    Approximately one million antiprotons have been captured in a large scale Penning trap at the Low Antiproton Ring (LEAR) at CERN. This has opened new discussions of the possible use of ultra-low energy antiprotons for gravitational physics as well as for precision spectroscopy of anti hydrogen for CPT tests

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

    Energy Technology Data Exchange (ETDEWEB)

    Burnham Stokes

    2006-06-30

    Results are reported on the reaction {gamma}p {yields} 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 {sigma} = 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/c{sup 2} 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.

  14. 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.

  15. 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...

  16. Antiproton-Nucleus Interaction and Coulomb Effect at High Energies

    Institute of Scientific and Technical Information of China (English)

    ZHOU Li-Juan; WU Qing; GU Yun-Ting; MA Wei-Xing; TAN Zhen-Qiang; HU Zhao-Hui

    2005-01-01

    The Coulomb effect in high energy antiproton-nucleus elastic and inelastic scattering from 12C and 16O is studied in the framework of Glauber multiple scattering theory for five kinetic energies ranged from 0.23 to 1.83 GeV.A microscopic shell-model nuclear wave functions, Woods-Saxon single-particle wave functions, and experimental pN amplitudes are used in the calculations. The results show that the Coulomb effect is of paramount importance for filling up the dips of differential cross sections. We claim that the present result for inelastic scattering of antiproton-12C is sufficiently reliable to be a guide for measurements in the very near future. We also believe that antiproton nucleus elastic and inelastic scattering may produce new information on both the nuclear structure and the antinucleon-nucleon interaction, in particular the p-neutron interaction.

  17. 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.

  18. Bucket shaking stops bunch dancing in Tevatron

    International Nuclear Information System (INIS)

    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.

  19. Antiproton-induced fission for space power and propulsion applications

    International Nuclear Information System (INIS)

    The Gasdynamic Mirror[GDM] fusion reactor is investigated for use as a bi-modal propulsion device when driven by antiprotons.The deuterium-tritium[DT] fusion reactions in the device will be initiated by the heating provided by the fission fragments and annihilation products resulting from the 'at rest' annihilation of antiprotons in U-238 target nuclei.The energetic pions and muons of the proton-antiproton[or neutron]annihilation in the U-238 nucleus can heat a DT plasma to several keV during their relatively short lifetimes.The remaining heating to about 10 keV is provided by the fission fragments.Fissioning of U-238 by 'at rest' annihilation of antiprotons has been shown to be 100% efficient,and the process can thus be effectively used in heating a suitable plasma to thermonuclear temperatures.With GDM as a steady state fusion reactor,and assuming certain efficiencies for the various components of the system,we calculate the energy multiplication factor 'Q' needed to sustain the steady-state operation for either the 'propulsive' mode or the 'power-producing' mode.With the aid of a system and mission analyses,we find that approximately 3.5 micrograms of antiprotons are required to accomplish a round mission to Mars in about 59 days.A similar amount is required to initiate and sustain the power-producing mode where gigawatts of electric power may be generated.Although roughly nanograms of antiprotons are currently produced annually,it is expected that hundreds of milligrams or even several grams will be produced annually in the next decade or so when Mars missions may be contemplated

  20. 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.

  1. 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.

  2. Second Stop and Sbottom Searches with a Stealth Stop

    CERN Document Server

    Cheng, Hsin-Chia; Qin, Qin

    2016-01-01

    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 $\\tilde{t}_2 \\to \\tilde{t}_1 Z$ and $\\tilde{t}_2 \\to \\tilde{t}_1 h$. 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 $\\tilde{t}_2 \\to \\tilde{b}_1 W$ and $\\tilde{b}_1 \\to \\tilde{t}_1 W$ as long as they are open. The decay chains can be even more complex if there ar...

  3. 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.

  4. Prospects of CPT tests using antiprotonic helium and antihydrogen

    International Nuclear Information System (INIS)

    Testing CPT to the highest possible precision using the laser spectroscopy of antiprotonic helium atoms (a neutral three-body system consisting of an antiproton, a helium nucleus and an electron) is the current goal of ASACUSA collaboration at CERN AD. The present status and future prospects are discussed in the first half of the talk. Our program will be extended in the future to include the microwave spectroscopy of ground-state hyperfine splitting of antihydrogen. The physics motivations and possible measurement schemes are presented in the second half

  5. Relativistic hydrodynamics, heavy ion reactions and antiproton annihilation

    International Nuclear Information System (INIS)

    The application of relativistic hydrodynamics to relativistic heavy ions and antiproton annihilation is summarized. Conditions for validity of hydrodynamics are presented. Theoretical results for inclusive particle spectra, pion production and flow analysis are given for medium energy heavy ions. The two-fluid model is introduced and results presented for reactions from 800 MeV per nucleon to 15 GeV on 15 GeV per nucleon. Temperatures and densities attained in antiproton annihilation are given. Finally, signals which might indicate the presence of a quark-gluon plasma are briefly surveyed

  6. Rapidity dependence of anti-proton production in relativistic heavy ion collisions at 14.6 GeV/c per nucleon

    International Nuclear Information System (INIS)

    Experiment E859 at Brookhaven National Laboratory is an extension of experiment E802, using additional tracking chambers and a new second-level trigger to provide on-line particle identification, thereby providing better event selection and allowing higher beam intensities to be used. The anti-proton measurements made by E802 have been extended to lower rapidities and the statistics in the y-pt regions already studied have been improved by approximately an order of magnitude. The authors present dn/dy distributions and cross-sections for antiproton production in the rapidity range 0.6 < y < 1.7, for 14.6 GeV/c Si beams on Al and Au targets. In addition, anti-lambda production will be discussed

  7. The K17 beamline for stopping kaons at Nimrod

    International Nuclear Information System (INIS)

    The design, construction, commissioning and present status of a stopped kaon beam line at Nimrod are described. The line, which operates at 600 MeV/c and uses a D.C. electric field separator is also compared with other lines used for this purpose. (author)

  8. Stopping-power ratios for dosimetry

    International Nuclear Information System (INIS)

    The determination of the absorbed dose at a specified location in a medium irradiated with an electron or photon beam normally consists of two steps: (1) the determination of the mean absorbed dose to a detector by using a calibration factor or performing an absolute measurement, (2) the determination of the absorbed dose to the medium at the point of interest by calculations based on the knowledge of the absorbed dose to the detector and the different stopping and scattering properties of the medium and the detector material. When the influence of the detector is so small that the electron fluence in the medium is not modified, the ratio of the mass collision stopping power of the two materials accounts for the differences in energy deposition, and provides a conversion factor to relate the absorbed dose in both materials. Today, all national and international dosimetry protocols and codes of practice are based on such procedures, and the user easily can carry out these steps using tabulated data to convert a measured quantity to absorbed dose in the irradiated medium at the location of interest. Effects due to the spatial extension of the detector are taken into account using perturbation correction factors. The Monte Carlo method has become the most common and powerful calculational technique for determining the electron fluence (energy spectra) under different irradiation conditions. Cavity theory is then used to calculate stopping-power ratios. In this chapter, the different steps needed to evaluate s-ratios will be considered, emphasizing the different types of cavity-theory integrals and the Monte Carlo techniques used to derive the necessary electron spectra in the range of energies commonly used in radiation dosimetry, i.e., photon and electron beams with energies up to 50 MeV

  9. 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.

  10. Spin Observables in Antilambda-Lambda Production from Antiproton-Proton Annihilation with a Transverse Inital State Polarization

    CERN Document Server

    Paschke, K; Paschke, Kent; Quinn, Brian

    2000-01-01

    The formalism describing the scattering of two spin-1/2 objects is reviewed for the case of antilambda-lambda production from antiproton-proton annihilation. It is shown that an experiment utilizing a transverse target polarization can, in principle, completely determine the spin structure of the reaction. Additional measurements, even those using both beam and target polarizations, would not be sensitive to any additional spin dynamics. Thus, the transverse target polarization allows access to the complete set of spin observables, not just the subset upon which the literature has previously focused. This discussion is especially relevant in light of the data collected by PS185/3 at LEAR.

  11. 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...

  12. The Facility for Antiproton and Ion Research FAIR Cosmic Matter in the Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Stoecker, H. [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, Planckstr. 1, D-64291 Darmstadt (Germany); Institut fuer Theoretische Physik, Goethe Universitaet Frankfurt, Max-von-Laue Str. 1, D-60438 Frankfurt Main (Germany); Institut fuer Kernphysik, Goethe Universitaet Frankfurt, Max-von-Laue Str. 1, D-60438 Frankfurt Main (Germany); Frankfurt Institute for Advanced Studies, Ruth-Moufang-Str. 1, D-60438 Frankfurt am Main (Germany); Sturm, C. [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, Planckstr. 1, D-64291 Darmstadt (Germany); Institut fuer Kernphysik, Goethe Universitaet Frankfurt, Max-von-Laue Str. 1, D-60438 Frankfurt Main (Germany)

    2011-07-15

    Cosmic matter in the laboratory - a broad spectrum of unprecedented fore-front research becomes available at the Facility for Antiproton and Ion Research, FAIR. The new facility will be constructed within the next seven years adjacent to the existing accelerator complex of the GSI Helmholtz Centre for Heavy Ion Research at Darmstadt/Germany. On October 4th, 2010, nine countries signed the international agreement on the construction of FAIR which will start in 2012. First beam will be delivered in 2017/2018 providing worldwide unique accelerator and experimental facilities. This will open the way for a large variety of experiments in hadron, nuclear, atomic and plasma physics as well as applied sciences which will be briefly described in this article. A few more details will be given on heavy-ion collisions providing a tool to study strongly interacting matter under extreme conditions.

  13. Secondary antiprotons as a Galactic Dark Matter probe

    CERN Document Server

    Evoli, Carmelo; Grasso, Dario

    2015-01-01

    We present a novel determination of the astrophysical uncertainties associated to the secondary antiproton flux originating from cosmic-ray spallation on the interstellar gas. We select a set of propagation models compatible with the recent B/C data from PAMELA, and find those providing minimal and maximal antiproton fluxes in different energy ranges. We use this result to determine the most conservative bounds on relevant Dark Matter (DM) annihilation channels: We find that the recent claim of a DM interpretation of a gamma-ray excess in the Galactic Center region cannot be ruled out by current antiproton data. Finally, we discuss the impact of the recently released preliminary data from AMS-02. In particular, we provide a reference model compatible with proton, helium and B/C spectra from this experiment. Remarkably, the main propagation parameters of this model are in perfect agreement with the best fit presented in our earlier statistical analyses. We also show that the antiproton-to-proton ratio does not...

  14. 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 (...

  15. 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.

  16. Delta-Isobar Production in Antiproton Annihilation on the Deuteron

    OpenAIRE

    Lykasov, G. I.; Bussa, M. P.; Valacca, L.

    1997-01-01

    The annihilation of antiprotons on deuterons at rest are investigated for the case when pion-nucleon and pion-delta-isobar pairs are produced. The two-step mechanism is investigated by analysing these processes when either neutral particles and charged ones are produced. Some predictions for the branching ratios are presented.

  17. Beam position monitor R&D for keV ion beams

    CERN Document Server

    Naveed, S; Nosych, A; Søby,L

    2013-01-01

    Beams of cooled antiprotons at keV energies shall be provided by the Ultra-low energy Storage Ring (USR) at the Facility for Low energy Antiproton and Ion Research (FLAIR) and the Extra Low ENergy Antiproton ring (ELENA) at CERN's Antiproton Decelerator (AD) facility. Both storage rings put challenging demands on the beam position monitoring (BPM) system as their capacitive pick-ups should be capable of determining the beam position of beams at low intensities and low velocities, close to the noise level of state-of-the-art electronics. In this contribution we describe the design and anticipated performance of BPMs for low-energy ion beams with a focus on the ELENA orbit measurement systems. We also present the particular challenges encountered in the numerical simulation of pickup response at very low beta values. Finally, we provide an outlook on how the implementation of faster algorithms for the simulation of BPM characteristics could potentially help speed up such studies considerably.

  18. NONLINEAR ION STOPPING IN PLASMA

    OpenAIRE

    Avilov, S.; Meyer-ter-Vehn, J.; Peter, Th.

    1988-01-01

    We present an exact nonlinear solution of the one-dimensional Coulomb-Vlasov equations describing the stopping power of ions moving through a plasma. The solution is compared with the results of the corresponding linearized equations which are commonly used. We discuss the genuinely nonlinear regime. Nonlinear effects become important for highly charged ions at relatively low velocity. For heavy ion stopping in plasma they are relevant close to the end of the range. The method and the results...

  19. 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...

  20. Constraints on particle dark matter from cosmic-ray antiprotons

    International Nuclear Information System (INIS)

    Cosmic-ray antiprotons represent an important channel for dark matter indirect-detection studies. Current measurements of the antiproton flux at the top of the atmosphere and theoretical determinations of the secondary antiproton production in the Galaxy are in good agreement, with no manifest deviation which could point to an exotic contribution in this channel. Therefore, antiprotons can be used as a powerful tool for constraining particle dark matter properties. By using the spectrum of PAMELA data from 50 MV to 180 GV in rigidity, we derive bounds on the dark matter annihilation cross section (or decay rate, for decaying dark matter) for the whole spectrum of dark matter annihilation (decay) channels and under different hypotheses of cosmic-rays transport in the Galaxy and in the heliosphere. For typical models of galactic propagation, the constraints are strong, setting a lower bound on the dark matter mass of a ''thermal'' relic at about 40–80 GeV for hadronic annihilation channels. These bounds are enhanced to about 150 GeV on the dark matter mass, when large cosmic-rays confinement volumes in the Galaxy are considered, and are reduced to 3–4 GeV for annihilation to light quarks (no bound for heavy-quark production) when the confinement volume is small. Bounds for dark matter lighter than few tens of GeV are due to the low energy part of the PAMELA spectrum, an energy region where solar modulation is relevant: to this aim, we have implemented a detailed solution of the transport equation in the heliosphere, which allowed us not only to extend bounds to light dark matter, but also to determine the uncertainty on the constraints arising from solar modulation modelling. Finally, we estimate the impact of soon-to-come AMS-02 data on the antiproton constraints

  1. Measurement of the antiproton magnetic moment and a determination of the LS-term for the antiproton-nucleus-interaction

    International Nuclear Information System (INIS)

    The subjects of this thesis are a measurement of the antiproton magnetic moment, a particle property, with the aim of testing the CPT-theorem for the strong interaction and the investigation of a possible spin-orbit-term of the anti p-nucleus-interaction. For both aspects the information is given in the finestructure-splitting of antiprotonic X-ray-transitions from heavy nuclei, since only for those the splitting is observable. From the finestructure-splitting of the transition 11→10 in 208Pb the magnetic moment of the antiproton can be calculated. The result of this best measurement up to now is μ sub anti p = (-2.8007±0.0091)μN. In between the error bars it confirms the CPT-Theorem and the new average value for the difference of the antiproton magnetic moment from the proton magnetic moment is (μp-anti μ sub anti p)/average = (-2.5±3).10-3. At the same time the limits of our detectors are described and other possibilities are discussed. In 174Yb one observes a splitting of the last observable transition 9→8, which is influenced by the strong interaction. From our measurement we find that the measured splitting is different from the calculated electromagnetic value and the Lorentz-widths of both line components are different as well. It is ΔEsw = 58±25±13 eV and ΔΓ = 195±58±20 eV. As result we find a sign for the existence of a spin-orbit-term of the antiproton-nucleus-interaction. Nevertheless is has to be confirmed in further experiments. (orig./HSI)

  2. Bucket Shaking Stops Bunch Oscillations In The Tevatron

    CERN Document Server

    Tan, C Y

    2011-01-01

    Bunches in the Tevatron are known to exhibit longitudinal oscillations which persist indefinitely. These oscillations are colloquially called "dancing bunches". Although the dancing bunches do not cause single bunch emittance growth or beam loss at injection, it leads to bunch lengthening at collisions. In operations, a longitudinal damper has been built which stops this dance and damps out coupled bunch modes. Recent theoretical work predicts that the dance can also be stopped by an appropriate change in the bunch distribution. This paper shows the Tevatron experiments which support this theory.

  3. 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...

  4. Correction of unevenness in recycler beam profile

    Energy Technology Data Exchange (ETDEWEB)

    Crisp, J.; Hu, M.; Ng, K.Y.; /Fermilab

    2006-05-01

    A beam confined between two rf barriers in the Fermilab Recycler Ring exhibits very uneven longitudinal profile. This leads to the consequence that the momentum-mined antiproton bunches will have an intolerable variation in bunch intensity. The observed profile unevenness is the result of a tiny amount of rf imperfection and rf beam-loading. The profile unevenness can be flattened by feeding back the uneven rf fan-back gap voltage to the low-level rf.

  5. Fermilab Proton Beam for Mu2e

    Energy Technology Data Exchange (ETDEWEB)

    Syphers, M.J.; /Fermilab

    2009-10-01

    Plans to use existing Fermilab facilities to provide beam for the Muon to Electron Conversion Experiment (Mu2e) are under development. The experiment will follow the completion of the Tevatron Collider Run II, utilizing the beam lines and storage rings used today for antiproton accumulation without considerable reconfiguration. The proposed Mu2e operating scenario is described as well as the accelerator issues being addressed to meet the experimental goals.

  6. Calculation of transition probabilities and ac Stark shifts in two-photon laser transitions of antiprotonic helium

    International Nuclear Information System (INIS)

    Numerical ab initio variational calculations of the transition probabilities and ac Stark shifts in two-photon transitions of antiprotonic helium atoms driven by two counter-propagating laser beams are presented. We found that sub-Doppler spectroscopy is, in principle, possible by exciting transitions of the type (n,L)→(n-2,L-2) between antiprotonic states of principal and angular momentum quantum numbers n∼L-1∼35, first by using highly monochromatic, nanosecond laser beams of intensities 104-105 W/cm2, and then by tuning the virtual intermediate state close (e.g., within 10-20 GHz) to the real state (n-1,L-1) to enhance the nonlinear transition probability. We expect that ac Stark shifts of a few MHz or more will become an important source of systematic error at fractional precisions of better than a few parts in 109. These shifts can, in principle, be minimized and even canceled by selecting an optimum combination of laser intensities and frequencies. We simulated the resonance profiles of some two-photon transitions in the regions n=30-40 of the p4He+ and p3He+ isotopes to find the best conditions that would allow this.

  7. First observation of dijet events with an antiproton tag at s**(1/2) = 1.96 TeV using the D0 Forward Proton Detector

    Energy Technology Data Exchange (ETDEWEB)

    Strang, Michael Allen

    2005-07-01

    The Forward Proton Detector (FPD) is a new sub-system of the D0 detector, a 5000 ton particle physics detector located at the Fermilab Tevatron proton-antiproton collider. The FPD was implemented for the Tevatron Run II and gives access to a wide range of diffractive scattering processes, where one or both of the beam particles remain intact. The analysis described in this thesis makes use of the dipole spectrometer of the FPD to tag outgoing antiprotons in events that have a dijet signature in the central D0 calorimeter. Properties of jets with a diffractive tag signature are compared to jets without such a signature yielding the first observation of tagged diffractive dijets at a 1.96 TeV center-of-mass energy.

  8. 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.

  9. Preparations for HFS spectroscopy of antiprotonic 3He

    International Nuclear Information System (INIS)

    Full text: Antiprotonic helium (pHe) is a neutral exotic atom, consisting of a helium nucleus, an electron and an antiproton. The interactions of the angular momenta and spins of its constituents cause splitting within the principle states. The measured transition frequencies between hyperfine levels can be compared with three-body QED calculations as a test of the theory. Previous measurements have been performed on p4He. The next two years will be dedicated to measuring a similar transition within p3He. Due to the additional coupling to the helion spin, it consists of an octuplet of states instead of a quadruplet. A new microwave cavity has been designed and is being constructed for the transition frequency of 11.14 GHz. This cavity has been simulated using the high frequency structure simulator HFSS to obtain the correct cavity dimensions. A new cryostat to cool the target is under construction. Numerical simulations are also in progress. (author)

  10. Testing quantum chromodynamics in anti-proton reactions

    Energy Technology Data Exchange (ETDEWEB)

    Brodsky, S.J.

    1987-10-01

    An experimental program with anti-protons at intermediate energy can serve as an important testing ground for QCD. Detailed predictions for exclusive cross sections at large momentum transfer based on perturbative QCD and the QCD sum rule form of the proton distribution amplitude are available for anti p p ..-->.. ..gamma gamma.. for both real and virtual photons. Meson-pair and lepton-pair final states also give sensitive tests of the theory. The production of charmed hadrons in exclusive anti p p channels may have a non-negligible cross section. Anti-proton interactions in a nucleus, particularly J/psi production, can play an important role in clarifying fundamental QCD issues, such as color transparency, critical length phenomena, and the validity of the reduced nuclear amplitude phenomenology.

  11. 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.

  12. 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.

  13. Proton-antiproton annihilation into two photons at large s

    CERN Document Server

    Weiss, C

    2002-01-01

    Exclusive proton-antiproton annihilation into two photons can be viewed as the Compton process in the crossed channel. At large s (~10 GeV^2) and |t|,|u| s this process can be described by a generalized partonic picture, analogous to the 'soft mechanism' in wide-angle real Compton scattering. The two photons are emitted in the annihilation of a single fast quark and antiquark ('handbag graph'). The transition of the p-pbar system to a q-qbar pair through soft interactions is described by double distributions, which can be related to the timelike proton elastic form factors as well as, by crossing symmetry, to the usual quark--antiquark distributions in the nucleon. We estimate that this reaction should be observable with reasonable statistics at the proposed 1.5..15 GeV high-luminosity antiproton storage ring (HESR) at GSI.

  14. Testing quantum chromodynamics in anti-proton reactions

    International Nuclear Information System (INIS)

    An experimental program with anti-protons at intermediate energy can serve as an important testing ground for QCD. Detailed predictions for exclusive cross sections at large momentum transfer based on perturbative QCD and the QCD sum rule form of the proton distribution amplitude are available for anti p p → γγ for both real and virtual photons. Meson-pair and lepton-pair final states also give sensitive tests of the theory. The production of charmed hadrons in exclusive anti p p channels may have a non-negligible cross section. Anti-proton interactions in a nucleus, particularly J/psi production, can play an important role in clarifying fundamental QCD issues, such as color transparency, critical length phenomena, and the validity of the reduced nuclear amplitude phenomenology

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

    DEFF Research Database (Denmark)

    Bassler, Niels; Knudsen, Helge; Møller, Søren Pape; Petersen, Jørgen B.B.; Rahbek, Dennis Bo; Uggerhøj, Ulrik Ingerslev

    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....

  16. 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.

  17. Current status of antiproton impact ionization of atoms and molecules: theoretical and experimental perspectives

    DEFF Research Database (Denmark)

    Kirchner, Tom; Knudsen, Helge

    2011-01-01

    Experimental and theoretical progress in the field of antiproton-impact-induced ionization of atoms and molecules is reviewed. We describe the techniques used to measure ionization cross sections and give an overview of the experimental results supplemented by tables of all existing data. An...... status of our understanding of antiproton impact ionization. The related issues of energy loss measurements and antiproton therapy are briefly described and directions for possible future work are pointed out as well....

  18. Asymmetric antiproton debuncher: No bad mixing, more good mixing

    International Nuclear Information System (INIS)

    An asymmetric lattice for the Fermilab Antiproton Debuncher is designed. The lattice has zero mixing between the pickups and the kickers (bad mixing) while the mixing in the rest of the machine (good mixing) can be varied (even during the operation of the machine) in order to optimize the stochastic cooling. As an example, a lattice with zero bad mixing and twice the good mixing is presented. The betatron cooling rate in this lattice is twice its present value

  19. The discovery of geomagnetically trapped cosmic ray antiprotons

    OpenAIRE

    Adriani, O.; Barbarino, G. C.; Bazilevskaya, G. A.; Bellotti, R.; M. Boezio; Bogomolov, E.A.; M. Bongi; Bonvicini, V.; Borisov, S.; Bottai, S.; Bruno, A.; F. Cafagna; Campana, D.; Carbone, R.; Carlson, P.

    2011-01-01

    The existence of a significant flux of antiprotons confined to Earth's magnetosphere has been considered in several theoretical works. These antiparticles are produced in nuclear interactions of energetic cosmic rays with the terrestrial atmosphere and accumulate in the geomagnetic field at altitudes of several hundred kilometers. A contribution from the decay of albedo antineutrons has been hypothesized in analogy to proton production by neutron decay, which constitutes the main source of tr...

  20. 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.)

  1. Physics at the Fermilab Tevatron Proton-Antiproton Collider

    International Nuclear Information System (INIS)

    These lectures discuss a selection of QCD and Electroweak results from the CDF and D0 experiments at the Fermilab Tevatron Proton-Antiproton Collider. Results are presently based on data samples of about 20 pb-1 at a center-of-mass energy of 1.8 TeV. Results discussed include jet production, direct photon production, W mass and width measurements, the triboson coupling, and most exciting of all, evidence for top quark production

  2. 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...

  3. Antihydrogen formation by autoresonant excitation of antiproton plasmas

    International Nuclear Information System (INIS)

    In efforts to trap antihydrogen, a key problem is the vast disparity between the neutral trap energy scale (∼ 50 μeV), and the energy scales associated with plasma confinement and space charge (∼1 eV). In order to merge charged particle species for direct recombination, the larger energy scale must be overcome in a manner that minimizes the initial antihydrogen kinetic energy. This issue motivated the development of a novel injection technique utilizing the inherent nonlinear nature of particle oscillations in our traps. We demonstrated 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 or tenuous 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. The nature of this injection overcomes some of the difficulties associated with matching the energies of the charged species used to produce antihydrogen.

  4. 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.)

  5. Charged pion albedo induced by cosmic antiproton interactions with the lunar surface

    International Nuclear Information System (INIS)

    We report the calculations of the energy spectra and fluxes of single and double albedo charged pions generated by cosmic proton and antiproton interactions with the lunar surface. Properties of such spectra and related fluxes are investigated in order to clarify some important facets of the antiproton detection via charged pion albedo flux from the lunar surface. Pion albedo measurement may represent a novel approach for the identification of cosmic antiprotons using the lunar surface as a calorimeter. Future scientific programs on the Moon designed to measure antiproton flux may benefit from the results of these calculations. (author)

  6. Measurement of cosmic ray antiprotons from 3.7 to 19 GeV

    Energy Technology Data Exchange (ETDEWEB)

    Hof, M.; Pfeifer, C.; Menn, W.; Simon, M. [Siegen Univ. (Germany); Golden, R.L.; Stochaj, S.J. [New Mexico State Univ., Las Cruces, NM (United States). Particle Astrophysics Laboratory; Stephens, S.A. [Tata Institute of Fundamental Research, Bombay (International Commission on Radiation Units and Measurements); Basini, G.; Ricci, M. [INFN, Laboratori Nazionali, Frascati, Rome (Italy)

    1996-02-01

    The antiproton to proton ratio in the cosmic rays has been measured in the energy range from 3.7 to 19 GeV. This measurement was carried out using a balloon-borne superconducting magnetic spectrometer along with a gas Cherenkov counter, an imaging calorimeter and a time of flight scintillator system. The measured antiproton to proton ratio was determined to be 1.24 (+0.68, -0.51)X 10{sup -4}. The present result along with other recent observations show that the observed abundances of antiprotons are consistent with models, in which antiprotons are produced as secondaries during the propagation of cosmic rays in the galaxy.

  7. 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...

  8. 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…

  9. 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...

  10. Child Violence Can Be Stopped

    OpenAIRE

    Jennifer Knot

    2000-01-01

    Mehr Khan argues that education, love and support can stop child violence. He argues that the idea that some children are born ‘bad’ and destined to be violent is outdated. Children become violent because of the violence and depravation they experience. Development (2000) 43, 53–54. doi:10.1057/palgrave.development.1110117

  11. 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,…

  12. Stop researching transformational leadership! Now!

    OpenAIRE

    Tummers, Lars

    2013-01-01

    markdownabstract__Intro__ Researchers all over the world, stop with your research on transformational leadership! Now! This could be the provocative conclusion after reading the recent article of Profs. Daan van Knippenberg and Sim Sitkin in The Academy of Management Annals (2013). These leadership professors write about the problems surrounding transformational leadership.

  13. 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.

  14. Experimental Studies of Compensation of Beam-Beam Effects with Tevatron Electron Lenses

    Energy Technology Data Exchange (ETDEWEB)

    Shiltsev, V.; /Fermilab; Alexahin, Yu.; Bishofberger, Kip; Kamerdzhiev, V.; Parkhomchuk, V.; Reva, V.; Solyak, N.; Wildman, D.; Zhang, X.-L.; Zimmermann, F.; /Fermilab /Los Alamos /Novosibirsk, IYF /CERN

    2008-02-01

    Applying the space-charge forces of a low-energy electron beam can lead to a significant improvement of the beam-particle lifetime limit arising from the beam-beam interaction in a high-energy collider [1]. In this article we present the results of various beam experiments with 'electron lenses', novel instruments developed for the beam-beam compensation at the Tevatron, which collides 980-GeV proton and antiproton beams. We study the dependencies of the particle betatron tunes on the electron beam current, energy and position; we explore the effects of electron-beam imperfections and noises; and we quantify the improvements of the high-energy beam intensity and the collider luminosity lifetime obtained by the action of the Tevatron Electron Lenses.

  15. 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.

  16. Electron Beam Size Measurements in a Cooling Solenoid

    CERN Document Server

    Kroc, Thomas K; Burov, Alexey; Seletsky, Sergey; Shemyakin, Alexander V

    2005-01-01

    The Fermilab Electron Cooling Project requires a straight trajectory and constant beam size to provide effective cooling of the antiprotons in the Recycler. A measurement system was developed using movable appertures and steering bumps to measure the beam size in a 20 m long, nearly continuous, solenoid. This paper discusses the required beam parameters, the implimentation of the measurement system and results for our application.

  17. Low-energy electronic stopping for boron in beryllium

    International Nuclear Information System (INIS)

    The range distribution for 50-keV boron bombarding beryllium was measured by an energetic ion-beam backscattering technique using helium ions. This distribution was compared with the range calculated with computer code EDEP1, with the result k 0.101 ± 0.013 for the electronic-stopping k-value. This value is compared with the results of recent interpolations from measurements of other elements. (author)

  18. 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......, for some geometric Lévy processes, the problem has a solution only if randomized stopping is allowed. When randomized stopping is allowed, we give a solution to the variance problem. We identify the Lévy processes for which the allowance of randomized stopping times increases the maximum variance....... When it does, we also solve the variance problem without randomized stopping....

  19. 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

    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.

  20. 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.

  1. Bus Stop - Environment Connection: Do Characteristics of the Built Environment Correlate with Bus Stop Crime?

    OpenAIRE

    Robin S Liggett; Loukaitou-Sideris, Anastasia; Iseki, Hiroyuki

    2003-01-01

    Can we understand why some bus stops are safe and others are crime-ridden? Can we predict which features of the bus stop environment are likely to encourage or discourage crime? Can we design safer bus stops? These questions are addressed by exploring the relationship between environmental variables and bus stop crime. An earlier study used crime data, along with environmental indicators, for a sample of 60 bus stops in downtown Los Angeles. Crime rates were higher for bus stops near alleys, ...

  2. 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.

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

    International Nuclear Information System (INIS)

    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

  4. Optimal Stopping under Nonlinear Expectation

    OpenAIRE

    Ekren, Ibrahim; Touzi, Nizar; Zhang, Jianfeng

    2012-01-01

    Let $X$ be a bounded c\\`adl\\`ag process with positive jumps defined on the canonical space of continuous paths. We consider the problem of optimal stopping the process $X$ under a nonlinear expectation operator $\\cE$ defined as the supremum of expectations over a weakly compact family of nondominated measures. We introduce the corresponding nonlinear Snell envelope. Our main objective is to extend the Snell envelope characterization to the present context. Namely, we prove that the nonlinear ...

  5. 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

  6. Review of the High Performance Antiproton Trap (HiPAT) Experiment at the Marshall Space Flight Center

    Science.gov (United States)

    Pearson, J. B.; Sims, Herb; Martin, James; Chakrabarti, Suman; Lewis, Raymond; Fant, Wallace

    2003-01-01

    The significant energy density of matter-antimatter annihilation is attractive to the designers of future space propulsion systems, with the potential to offer a highly compact source of power. Many propulsion concepts exist that could take advantage of matter-antimatter reactions, and current antiproton production rates are sufficient to support basic proof-of-principle evaluation of technology associated with antimatter- derived propulsion. One enabling technology for such experiments is portable storage of low energy antiprotons, allowing antiprotons to be trapped, stored, and transported for use at an experimental facility. To address this need, the Marshall Space Flight Center's Propulsion Research Center is developing a storage system referred to as the High Performance Antiproton Trap (HiPAT) with a design goal of containing 10(exp 12) particles for up to 18 days. The HiPAT makes use of an electromagnetic system (Penning- Malmberg design) consisting of a 4 Telsa superconductor, high voltage electrode structure, radio frequency (RF) network, and ultra high vacuum system. To evaluate the system normal matter sources (both electron guns and ion sources) are used to generate charged particles. The electron beams ionize gas within the trapping region producing ions in situ, whereas the ion sources produce the particles external to the trapping region and required dynamic capture. A wide range of experiments has been performed examining factors such as ion storage lifetimes, effect of RF energy on storage lifetime, and ability to routinely perform dynamic ion capture. Current efforts have been focused on improving the FW rotating wall system to permit longer storage times and non-destructive diagnostics of stored ions. Typical particle detection is performed by extracting trapped ions from HiPAT and destructively colliding them with a micro-channel plate detector (providing number and energy information). This improved RF system has been used to detect various

  7. Ionization of atomic hydrogen by 30 1000 keV antiprotons

    Energy Technology Data Exchange (ETDEWEB)

    Knudsen, H.; Mikkelsen, U.; Paludan, K. [Institute of Physics and Astronomy, University of Aarhus, DK-8000 Aarhus C (Denmark); Kirsebom, K.; Moller, S.P.; Uggerhoj, E. [Institute for Synchrotron Radiation, University of Aarhus, DK-8000 Aarhus C (Denmark); Slevin, J. [Department of Experimental Physics, St. Patrick`s College, Maynooth (Ireland); Charlton, M. [Department of Physics and Astronomy, University College London, London WC1E 6BT (United Kingdom); Morenzoni, E. [Paul Scherrer Institut, Villigen, CH-4234 (Switzerland)

    1995-06-05

    Ionization in collisions between antiprotons and atomic hydrogen is perhaps the least complicated and most fundamental process that can be treated by atomic-collision theory. We present measurements of the ionization cross section for 30--1000 keV antiprotons colliding with atomic hydrogen.

  8. A new cryogenic target and microwave cavity for hyperfine structure spectroscopy of antiprotonic helium

    International Nuclear Information System (INIS)

    Full text: A new cryostat with pulse tube refrigeration and gas-tight microwave cavity with a laser and antiproton window has been designed and built to study the hyperfine structure of antiprotonic helium-3. The improvements between this and the old system will be explained. (author)

  9. Antiproton small momentum transfer charge exchange scattering on protons at 30 GeV/c

    International Nuclear Information System (INIS)

    Antiproton charge exchange scattering on protons anti pp→anti nn is investigated with 30 GeV/c antiprotons at the IHEP accelerator. The experiment confirms the existence of a structure at small angles in the angular distribution of this reaction at high energies, observed earlier

  10. The PS 200 catching trap: A new tool for ultra-low energy antiproton physics

    International Nuclear Information System (INIS)

    Approximately one million antiprotons have been trapped and electron cooled in the PS200 catching trap from a single fast extracted pulse from LEAR. The system is described in detail, different extraction schemes are discussed, and possible applications of this instrument to ultra-low energy atomic and nuclear physics with antiprotons are mentioned

  11. Trapping of antiprotons -- a first step on the way to antihydrogen

    International Nuclear Information System (INIS)

    A first step towards producing and effectively utilizing antihydrogen atoms consists of trapping antiprotons. The immediate next step must then be to control, i.e. trap the produced antihydrogen. The current state of the art in trapping antiprotons and positrons is reviewed, and the challenges in trapping the resulting neutral particles are discussed

  12. Illuminating dark matter and primordial black holes with an interstellar antiproton spectrometer

    International Nuclear Information System (INIS)

    Interstellar antiproton fluxes can arise from dark matter annihilating or decaying into quarks or gluons that subsequently fragment into antiprotons. Evaporation of primordial black holes also can produce a significant antiproton cosmic-ray flux. Since the background of secondary antiprotons from spallation has an interstellar energy spectrum that peaks at 2 GeV and falls rapidly for energies below this, low-energy measurements of cosmic antiprotons are useful in the search for exotic antiproton sources. However, measurement of the flux near the earth is challenged by significant uncertainties from the effects of the solar wind. We suggest evading this problem and more effectively probing dark-matter signals by placing an antiproton spectrometer aboard an interstellar probe currently under discussion. We address the experimental challenges of a light, low-power-consuming detector, and present an initial design of such an instrument. This experimental effort could significantly increase our ability to detect, and have confidence in, a signal of exotic, nonstandard antiproton sources. Furthermore, solar modulation effects in the heliosphere would be better quantified and understood by comparing results to inverse modulated data derived from existing balloon and space-based detectors near the earth

  13. 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... operation other than starting and stopping the rotor. (Secs. 313(a), 601, 603, 604, Federal Aviation Act...

  14. Production and perception of glottal stops

    OpenAIRE

    Garellek, Marc

    2013-01-01

    This dissertation investigates how glottal stops are produced and perceived, and why they occur so frequently before word-initial vowels in languages of the world. Specifically, the goal of the production chapter was to determine whether glottal stops are truly glottal sounds. High-speed imaging of glottal stops uttered by five phonetically-trained English speakers was obtained using trans-oral videoendoscopy. When produced as plosives, glottal stops always had some form of vocal fold incursi...

  15. Measurements of cosmic ray antiprotons with PAMELA and studies of propagation models

    CERN Document Server

    Wu, Juan

    2012-01-01

    Studying the acceleration and propagation mechanisms of Galactic cosmic rays can provide information regarding astrophysical sources, the properties of our Galaxy, and possible exotic sources such as dark matter. To understand cosmic ray acceleration and propagation mechanisms, accurate measurements of different cosmic ray elements over a wide energy range are needed. The PAMELA experiment is a satellite-borne apparatus which allows different cosmic ray species to be identified over background. Measurements of the cosmic ray antiproton flux and the antiproton-to-proton flux ratio from 1.5 GeV to 180 GeV are presented in this thesis. Compared to previous experiments, PAMELA extends the energy range of antiproton measurements and provides significantly higher statistics. The derived antiproton flux and antiproton-to-proton flux ratio are consistent with previous measurements and generally considered to be produced as secondary products when cosmic ray protons and helium nuclei interact with the interstellar med...

  16. Ion optics and beam dynamics optimization at the HESR storage ring for the SPARC experiments with highly charged heavy ions

    OpenAIRE

    Kovalenko, Oleksandr

    2015-01-01

    The High-Energy Storage Ring (HESR) is a part of an upcoming International Facility for Antiproton and Ion Research (FAIR) at GSI in Darmstadt [1]. 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 [2–4]. Until recently, however, the existing ion optical lattic...

  17. Antihydrogen and mirror-trapped antiproton discrimination: Discriminating between antihydrogen and mirror-trapped antiprotons in a minimum-B trap

    OpenAIRE

    Amole, C.; Andresen, G. B.; Ashkezari, M. D.; Baquero-Ruiz, M.; Bertsche, W.; Butler, E.; Cesar, C. L.; S. Chapman; Charlton, M.; Deller, A.; Eriksson, S.; Fajans, J.; Friesen, T.; Fujiwara, M. C.; Gill, D. R.

    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 s...

  18. Top Production at the Tevatron: The Antiproton Awakens

    CERN Document Server

    ,

    2016-01-01

    A long time ago, at a laboratory far, far away, the Fermilab Tevatron collided protons and antiprotons at $\\sqrt{s} = 1.96$ TeV. The CDF and D0 experiments each recorded datasets of about 10 fb$^{-1}$. As such experiments may never be repeated, these are unique datasets that allow for unique measurements. This presentation describes recent results from the two experiments on top-quark production rates, spin orientations, and production asymmetries, which are all probes of the $p\\bar{p}$ initial state.

  19. 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.

  20. Pion production on exotic nuclei by antiproton annihilation

    International Nuclear Information System (INIS)

    Pion production by antiproton annihilation on neutron- or proton-rich nuclei is studied in a fully quantum mechanical description of the reaction process in terms of a distorted wave approach. The elementary elastic N-bar N and the N-bar N → nπ annihilation vertices are obtained from a t-matrix accounting for coupled channels effects. The theoretical amplitudes are used to derive a microscopic N-bar A optical model potential and the meson production vertices. Nuclear structure effects are taken into account microscopically. Results for meson production cross sections are presented.

  1. Measurement of 0.25 endash 3.2 GeV antiprotons in the cosmic radiation

    International Nuclear Information System (INIS)

    The balloon-borne isotope matter-antimatter experiment (IMAX) was flown from Lynn Lake, Manitoba Canada on 16 endash 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 GeV. Both the absolute flux of antiprotons and the antiproton/proton ratio are consistent with recent theoretical work in which antiprotons are produced as secondary products of cosmic ray interactions with the interstellar medium. This consistency implies a lower limit to the antiproton lifetime of ∼107 yr. copyright 1996 The American Physical Society

  2. Optimal stopping for predictive maintenance

    CERN Document Server

    de Saporta, Benoîte; Zhang, Huilong; Elegbede, Charles

    2011-01-01

    We present a numerical method to compute the optimal maintenance time for a complex dynamic system. An early intervention may be uselessly costly, but a late one may lead to a partial/complete failure of the system, which has to be avoided. One must therefore find a balance between these two extreme maintenance policies. To achieve this aim, we model the system by a stochastic hybrid process and propose a numerical method to optimize the maintenance time for this kind of processes. Mathematically, this is an optimal stopping problem. We apply our algorithm to the example of maintenance of a metallic structure subject to corrosion.

  3. Markkinointisuunnitelma : case Fitness Stop Oy

    OpenAIRE

    Tikkanen, Tuomas

    2011-01-01

    Tämän opinnäytetyön tarkoituksena oli luoda toimeksiantajayritykselle, Fitness Stop Oy:lle markkinointisuunnitelma. Työ sisältää markkinointisuunnitelman teoreettisen osuuden, jossa käsitellään markkinointisuunnitelman määritelmä osa-alueittain. Määritelmässä kerrotaan markkinointisuunnitelman tarpeellisuudesta yrityksille ja mitä sillä yritetään saavuttaa. Tarkoituksena oli luoda toimiva runko, jonka avulla yritys voi suunnitella ja toteuttaa markkinointiaan tulevaisuudessa. Markkinointi...

  4. 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)

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

    International Nuclear Information System (INIS)

    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 σ parallel and σ perpendicularto are deduced using the likelihood method. (orig.)

  6. 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.)

  7. 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...

  8. Antiproton-proton elastic scattering at 3.0 and 4.0 GeV/C

    International Nuclear Information System (INIS)

    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)

  9. Double antikaonic nuclear clusters in antiproton-{sup 3}He annihilation at J-PARC

    Energy Technology Data Exchange (ETDEWEB)

    Sakuma, Fuminori, E-mail: sakuma@ribf.riken.jp [RIKEN, RIKEN Nishina Center (Japan); Curceanu, Catalina [Laboratori Nazionali di Frascati dell' INFN (Italy); Iwasaki, Masahiko [RIKEN, RIKEN Nishina Center (Japan); Kienle, Paul [Technische Universiat Munchen (Germany); Ohnishi, Hiroaki [RIKEN, RIKEN Nishina Center (Japan); Tokuda, Makoto [The University of Tokyo, Department of Physics (Japan); Tsukada, Kyo [Tohoku University, Department of Physics (Japan); Widmann, Eberhard [Stefan-Meyer-Institut fuer Subatomare Physik (Austria); Yamazaki, Toshimitsu [RIKEN, RIKEN Nishina Center (Japan); Zmeskal, Johannes [Stefan-Meyer-Institut fuer Subatomare Physik (Austria)

    2012-12-15

    We search for double anti-kaon nuclear bound states in the p-bar annihilation reaction in {sup 3}He nuclei at rest. In view of the strongly attractive K-bar N interaction, the existence of nuclear clusters with more than one K{sup }- has been predicted theoretically. The double anti-kaon production in elementary antiproton annihilation at rest is forbidden because of the negative Q-value; however, a double anti-kaon nuclear bound state, such as K{sup }- K{sup }- pp, with deep binding energy would enable double anti-kaon production in the nuclei. In order to investigate the K{sup }- K{sup }- pp production in the p-bar + {sup 3}He {yields} K{sup +} + K{sup 0} + X (X = K{sup -} K{sup -} pp) channel, the produced K{sup }- K{sup }- pp cluster is identified both using missing mass spectroscopy via the K{sup + }K{sup 0} channel with a {Lambda}-tag, and invariant mass analysis of the expected decay particles from the K{sup }- K{sup }- pp cluster such as {Lambda}{Lambda}. We propose to perform the experiment at the existing K1.8BR beam line at J-PARC with the E15 spectrometer.

  10. Double antikaonic nuclear clusters in antiproton-3He annihilation at J-PARC

    Science.gov (United States)

    Sakuma, Fuminori; Curceanu, Catalina; Iwasaki, Masahiko; Kienle, Paul; Ohnishi, Hiroaki; Tokuda, Makoto; Tsukada, Kyo; Widmann, Eberhard; Yamazaki, Toshimitsu; Zmeskal, Johannes

    We search for double anti-kaon nuclear bound states in the bar p annihilation reaction in 3He nuclei at rest. In view of the strongly attractive bar K N interaction, the existence of nuclear clusters with more than one K - has been predicted theoretically. The double anti-kaon production in elementary antiproton annihilation at rest is forbidden because of the negative Q-value; however, a double anti-kaon nuclear bound state, such as K - K - pp, with deep binding energy would enable double anti-kaon production in the nuclei. In order to investigate the K - K - pp production in the bar p + ^3He to K^+ + K^0 + X (X = K^-K^-pp) channel, the produced K - K - pp cluster is identified both using missing mass spectroscopy via the K + K 0 channel with a Λ-tag, and invariant mass analysis of the expected decay particles from the K - K - pp cluster such as ΛΛ. We propose to perform the experiment at the existing K1.8BR beam line at J-PARC with the E15 spectrometer.

  11. Evidence for capacity sharing when stopping.

    Science.gov (United States)

    Verbruggen, Frederick; Logan, Gordon D

    2015-09-01

    Research on multitasking indicates that central processing capacity is limited, resulting in a performance decrement when central processes overlap in time. A notable exception seems to be stopping responses. The main theoretical and computational accounts of stop performance assume that going and stopping do not share processing capacity. This independence assumption has been supported by many behavioral studies and by studies modeling the processes underlying going and stopping. However, almost all previous investigations of capacity sharing between stopping and going have manipulated the difficulty of the go task while keeping the stop task simple. In the present study, we held the difficulty of the go task constant and manipulated the difficulty of the stop task. We report the results of four experiments in which subjects performed a selective stop-change task, which required them to stop and change a go response if a valid signal occurred, but to execute the go response if invalid signals occurred. In the consistent-mapping condition, the valid signal stayed the same throughout the whole experiment; in the varied-mapping condition, the valid signal changed regularly, so the demands on the rule-based system remained high. We found strong dependence between stopping and going, especially in the varied-mapping condition. We propose that in selective stop tasks, the decision to stop or not will share processing capacity with the go task. This idea can account for performance differences between groups, subjects, and conditions. We discuss implications for the wider stop-signal and dual-task literature. PMID:26036922

  12. Antiproton magnetic moment determined from the HFS of p-bar He+

    International Nuclear Information System (INIS)

    We report a determination of the antiproton magnetic moment, measured in a three-body system, independent of previous experiments. We present results from a systematic study of the hyperfine (HF) structure of antiprotonic helium where we have achieved a precision more than a factor of 10 better than our first measurement. A comparison between the experimental results and three-body quantum electrodynamic (QED) calculations leads to a new value for the antiproton magnetic moment μsp-bar=-2.7862(83)μN, which agrees with the magnetic moment of the proton within 2.9x10-3.

  13. Measurement of the branching ratio $\\Gamma(\\overline{p}p\\to e^{+}e^{-})/\\Gamma(\\overline{p}p\\to total)$ in antiproton-proton annihilation at rest

    CERN Document Server

    Bassompierre, G; Dalpiaz, P; Dalpiaz, P F; Gissinger, G; Jacquey, S; Peroni, C; Schneegans, M; Tecchio, L B

    1976-01-01

    Analyzing a sample of 220000 events from an experiment still in progress at the CERN Proton Synchrotron, 60 pairs of electrons with an energy above 700 MeV have been observed. The electrons, produced by annihilation of antiproton stopped in a liquid-hydrogen target, are detected with optical spark chambers and scintillation counters. Twenty-nine out of these 60 pairs have been found to be collinear; normalizing with respect to the hadronic two-body channels pi /sup +/ pi /sup -/ and K/sup +/K/sup -/, a branching raio B/sub ee/= Gamma (pp to e/sup +/e/sup -/) Gamma /(pp to total)=(3.2+or-0.9)*10/sup -7/ has been obtained. (11 refs).

  14. Relativistic corrections to stopping powers

    International Nuclear Information System (INIS)

    Relativistic corrections to the nonrelativistic Bethe-Bloch formula for the stopping power of matter for charged particles are traditionally computed by considering close collisions separately from distant collisions. The close collision contribution is further divided into the Mott correction appropriate for very small impact parameters, and the Bloch correction, computed for larger values. This division of the region of close collisions leads to a very cumbersome result if one generalizes the original Bloch procedure to relativistic energies. The authors avoid the resulting poorly specified scattering angle theta/sub o/ that divides the Mott and Bloch correction regimes by using the procedure suggested by Lindhard and applied by Golovchenko, Cox and Goland to determine the Bloch correction for relativistic velocities. 25 references, 2 figures

  15. Shell corrections in stopping powers

    Science.gov (United States)

    Bichsel, H.

    2002-05-01

    One of the theories of the electronic stopping power S for fast light ions was derived by Bethe. The algorithm currently used for the calculation of S includes terms known as the mean excitation energy I, the shell correction, the Barkas correction, and the Bloch correction. These terms are described here. For the calculation of the shell corrections an atomic model is used, which is more realistic than the hydrogenic approximation used so far. A comparison is made with similar calculations in which the local plasma approximation is utilized. Close agreement with the experimental data for protons with energies from 0.3 to 10 MeV traversing Al and Si is found without the need for adjustable parameters for the shell corrections.

  16. Investigations into beam monitors at the AE bar {g}IS experiment

    Science.gov (United States)

    Sosa, A.; Bravin, E.; Harasimowicz, J.; Jeff, A.; Welsch, C. P.

    2014-02-01

    Detailed diagnostic of antiproton beams at low energies is required for essentially all experiments at the Antiproton Decelerator (AD), but will be particularly important for the future Extra Low ENergy Antiproton ring (ELENA) and its keV beam lines to the different experiments. Many monitors have been successfully developed and operated at the AD, but in particular beam profile monitoring remains a challenge. A dedicated beam instrumentation and detector test stand has recently been setup at the AE bar {g}IS experiment (Antimatter Experiment: Gravity, Interferometry, Spectroscopy). Located behind the actual experiment, it allows for parasitic use of the antiproton beam at different energies for testing and calibration. With the aim to explore and validate different candidate technologies for future low energy beam lines, as well as the downstream antihydrogen detector in AE bar {g}IS, measurements have been carried out using Silicon strip and pixel detectors, a purpose-built secondary emission monitor and emulsions. Here, results from measurements and characterization of the different detector types with regard to their future use at the AD complex are presented.

  17. Pulsed septum magnet for the Fermilab antiproton source

    International Nuclear Information System (INIS)

    A 2 meter curved pulsed septum magnet for use in the Fermilab Antiproton Source is described. The magnet produces a peak field of 6 kGauss at a current of 20,000 Amperes within a 0.4 msec long pulse. The field uniformity obtained is ΔB/B<0.2% out to 3.8 cm from the copper septum. Power enters the magnet from the center resulting in very simple ends and the magnet incorporates at 0.5 cm steel guard which reduces the field to <1.4 Gauss in the zero-field region. The total septum thickness is 1.3 cm. The vacuum enclosure doubles as the stacking fixture for the magnet laminations allowing easy assembly of a magnet with a 50 m radius of curvature

  18. Survey and alignment of the Fermilab recycler antiproton storage ring

    International Nuclear Information System (INIS)

    In June of 1999 Fermilab commissioned a newly constructed antiproton storage ring, the 'Recycler Ring', in the Main Injector tunnel directly above the Main Injector beamline. The Recycler Ring is a fixed 8 GeV kinetic energy storage ring and is constructed of strontium ferrite permanent magnets. The 3319.4-meter-circumference Recycler Ring consists of 344 gradient magnets and 100 quadrupoles all of which are permanent magnets. This paper discusses the methods employed to survey and align these permanent magnets within the Recycler Ring with the specified accuracy. The Laser Tracker was the major instrument used for the final magnet alignment. The magnets were aligned along the Recycler Ring with a relative accuracy of ±0.25 mm. (author)

  19. An Update on the Depth-Dose Curve of Antiprotons

    DEFF Research Database (Denmark)

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

    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...... of dose still is missing in the Bragg-peak. This effect is also visible in the tail where the dose is underestimated in both types of simulations because of the missing annihilation energy/products. Conclusions: The shape of the Bragg-peak has some dependence on what material the antiprotons is...... 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...

  20. One-Particle Measurement of the Antiproton Magnetic Moment

    CERN Document Server

    DiSciacca, J; Marable, K; Gabrielse, G; Ettenauer, S; Tardiff, E; Kalra, R; Fitzakerley, D W; George, M C; Hessels, E A; Storry, C H; Weel, M; Grzonka, D; Oelert, W; Sefzick, T

    2013-01-01

    The antiproton $(\\bar{p})$ magnetic moment $\\mu \\bar{p} = \\mu_{\\bar{p}} S/(\\bar{h}/2)$ is proportional to its spin $S$. A single trapped $\\bar{p}$ is used for the first time to measure the $\\bar{p}$ magnetic moment in nuclear magnetons, giving $\\mu_\\bar{p}/\\mu N = -2.792 845 \\pm 0.000 012$. The 4.4 parts per million (ppm) uncertainty is 680 times smaller than previously realized. Comparing to the proton moment $\\mu_{p} = \\mu_{p} S/\\bar{h}/2)$ measured using the same method and trap electrodes gives $\\mu_{\\bar{p}}/\\mu_{p} = -1.000 000 \\pm 0.000 005$ to 5 ppm, consistent with the prediction of the CPT theorem.

  1. Decay of hot nuclei formed with energetic antiprotons (PS208)

    CERN Document Server

    Pienkowski, L; Eades, John; Egidy, T V; Figuera, P; Fuchs, H; Galin, J; Goldenbaum, F; Golubeva, Y S; Gulda, K; Hilscher, D; Iljinov, A S; Jahnke, U; Jastrzebski, J J; Kurcewicz, W; Lott, B; Morjean, M; Pausch, G; Peghaire, A; Polster, D; Proschitzki, S; Quednau, B; Rossner, H; Schmid, S; Schmid, W; Ziem, P

    1999-01-01

    Energetic antiproton-nucleus interactions allow to build up thermal excitation energies exceeding 800 MeV in nuclei of masses close to 200. We found that for these high excitation energies the fission process still remains a very significant exit channel. At excitation energies close to 800 MeV the fission process approaches 20-50% of the cross section for Ho, Au and U-like nuclei depending on the fission events selection criteria. The average intermediate mass fragment multiplicity at such high excitation energies is equal to about 1 and alpha particle multiplicity is equal to about 5 for all three reactions independently of the exit channel, including fission. A transition towards the multifragmentation is not observed.

  2. Calculation of stopping power ratios for carbon ion dosimetry

    Science.gov (United States)

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

    2006-05-01

    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, swater,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.

  3. Antiproton-nucleus interaction: review of the experimental situation

    International Nuclear Information System (INIS)

    This paper will review the experimental situation of a few well-defined channels of the anti-p-nucleus interaction where the antiproton does not annihilate. It will not mention any experiment which studies annihilation of antiporotons in nuclei. The anti-p-nucleus reactions that will be reviewed are the following: 1. A(anti-p,anti-p)A elastic scattering which deals with the anti-p-nucleus system in a positive energy state. 2. Anti-p-nucleus atoms where the anti-p-nucleus system is almost at zero energy and interacts mostly through the Coulomb interaction, the strong interaction being only a perturbation. 3. A(anti-p,p)X proton knock-out reaction used to produce possible bound states or resonances of the anti-p-nucleus system via strong interaction. The main reasons for studying these three channels are to provide information about the anti-p-nucleus optical potential and also, through microscopic calculations which use the elementary anti-NN amplitudes and the nuclear matter densities as inputs, to get information about these quantities. 4. A(anti-p,anti-p')A* inelastic scattering - inelastic in the sense that the nucleus is left in an excited state but the antiproton does not annihilate, that is it deals only with the elastic part of the elementary anti-NN amplitude. Inelastic scattering from collective states also sets constraints on the anti-p-nucleus potential when analysed in terms of coupled-channel calculations. When unnatural parity states are concerned, it provides a sensitive test of the spin and isospin components of these amplitudes. In addition, this paper will focus essentially on the recent experiments performed at LEAR

  4. 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.

  5. Spin Filtering of Stored (Anti)Protons: from FILTEX to COSY to AD to FAIR

    International Nuclear Information System (INIS)

    We review the theory of spin filtering of stored (anti) protons by multiple passage through a polarized internal target (PIT). The implications for the antiproton polarization buildup in the proposed PAX experiment at FAIR are discussed

  6. Beam-Beam Effects

    OpenAIRE

    Herr, W; Pieloni, T.

    2016-01-01

    One of the most severe limitations in high-intensity particle colliders is the beam-beam interaction, i.e. the perturbation of the beams as they cross the opposing beams. This introduction to beam-beam effects concentrates on a description of the phenomena that are present in modern colliding beam facilities.

  7. Beam-Beam Effects

    CERN Document Server

    Herr, W

    2014-01-01

    One of the most severe limitations in high-intensity particle colliders is the beam-beam interaction, i.e. the perturbation of the beams as they cross the opposing beams. This introduction to beam-beam effects concentrates on a description of the phenomena that are present in modern colliding beam facilities.

  8. Proton and antiproton production in deep inelastic muon-nucleon scattering at 280 GeV

    International Nuclear Information System (INIS)

    New results on proton and antiproton production in the target and current fragmentation regions of high energy muonnucleon scattering are presented. Proton and antiproton production is investigated as a function of Feynman x and rapidity. No significant difference is observed between production on hydrogen and deuterium targets. Correlations between pp, panti p and anti panti p pairs are analysed and the results are compared with the predictions of the Lund fragmentation model. (orig.)

  9. Proton and antiproton production in deep inelastic muon-nucleon scattering at 280 GeV

    Science.gov (United States)

    Arneodo, M.; Arvidson, A.; Aubert, J. J.; Badelek, B.; Beaufays, J.; Bee, C. P.; Benchouk, C.; Berghoff, G.; Bird, I.; Blum, D.; Böhm, E.; de Bouard, X.; Brasse, F. W.; Braun, H.; Broll, C.; Brown, S.; Brück, H.; Calen, H.; Chima, J. S.; Ciborowski, J.; Clifft, R.; Coignet, G.; Combley, F.; Coughlan, J.; D'Agostini, G.; Dahlgren, S.; Dengler, F.; Derado, I.; Dreyer, T.; Drees, J.; Düren, M.; Eckardt, V.; Edwards, A.; Edwards, M.; Ernst, T.; Eszes, G.; Favier, J.; Ferrero, M. I.; Figiel, J.; Flauger, W.; Foster, J.; Gabathuler, E.; Gajewski, J.; Gamet, R.; Gayler, J.; Geddes, N.; Grafström, P.; Grard, F.; Haas, J.; Hagberg, E.; Hasert, F. J.; Hayman, P.; Heusse, P.; Jaffré, M.; Jacholkowska, A.; Janata, F.; Jansco, G.; Johnson, A. S.; Kabuss, E. M.; Kellner, G.; Korbel, V.; Krüger, A.; Krüger, J.; Kullander, S.; Landgraf, U.; Lanske, D.; Loken, J.; Long, K.; Maire, M.; Malecki, P.; Manz, A.; Maselli, S.; Mohr, W.; Montanet, F.; Montgomery, H. E.; Nagy, E.; Nassalski, J.; Norton, P. R.; Oakham, F. G.; Osborne, A. M.; Pascaud, C.; Pawlik, B.; Payre, P.; Peroni, C.; Peschel, H.; Pessard, H.; Pettingale, J.; Pietrzyk, B.; Poensgen, B.; Pötsch, M.; Renton, P.; Ribarics, P.; Rith, K.; Rondio, E.; Sandacz, A.; Scheer, M.; Schlagböhmer, A.; Schiemann, H.; Schmitz, N.; Schneegans, M.; Scholz, M.; Schouten, M.; Schröder, T.; Schultze, K.; Sloan, T.; Stier, H. E.; Studt, M.; Taylor, G. N.; Thénard, J. M.; Thompson, J. C.; de La Torre, A.; Toth, J.; Urban, L.; Wallucks, W.; Whalley, M.; Wheeler, S.; Williams, W. S. C.; Wimpenny, S. J.; Windmolders, R.; Wolf, G.

    1987-12-01

    New results on proton and antiproton production in the target and current fragmentation regions of high energy muon-nucleon scattering are presented. Proton and antiproton production is investigated as a function of Feynman x and rapidity. No significant difference is observed between production on hydrogen and deuterium targets. Correlations between pp,pbar p andbar pbar p pairs are analysed and the results are compared with the predictions of the Lund fragmentation model.

  10. 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.

  11. 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.

  12. P-986 Letter of Intent: Medium-Energy Antiproton Physics at Fermilab

    Energy Technology Data Exchange (ETDEWEB)

    Asner, David M.; /Carleton U.; Phillips, Thomas J.; /Duke U.; Apollinari, Giorgio; Broemmelsiek, Daniel R.; Brown, Charles N.; Christian, David C.; Derwent, Paul; Gollwitzer, Keith; Hahn, Alan; Papadimitriou, Vaia; Stefanski, Ray; /Fermilab /INFN, Ferrara /Hbar Technol., West Chicago /IIT, Chicago /CHEP, Taegu /Luther Coll. /Michigan U. /Northwestern U. /Notre Dame U. /St. Xavier U., Chicago

    2009-02-05

    Fermilab has long had the world's most intense antiproton source. Despite this, the opportunities for medium-energy antiproton physics at Fermilab have been limited in the past and - with the antiproton source now exclusively dedicated to serving the needs of the Tevatron Collider - are currently nonexistent. The anticipated shutdown of the Tevatron in 2010 presents the opportunity for a world-leading medium-energy antiproton program. We summarize the current status of the Fermilab antiproton facility and review some physics topics for which the experiment we propose could make the world's best measurements. Among these, the ones with the clearest potential for high impact and visibility are in the area of charm mixing and CP violation. Continued running of the Antiproton Source following the shutdown of the Tevatron is thus one of the simplest ways that Fermilab can restore a degree of breadth to its future research program. The impact on the rest of the program will be minor. We request a small amount of effort over the coming months in order to assess these issues in more detail.

  13. New Calculation of Antiproton Production by Cosmic Ray Protons and Nuclei

    Science.gov (United States)

    Kachelriess, Michael; Moskalenko, Igor V.; Ostapchenko, Sergey S.

    2015-04-01

    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. This 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 Carlo (MC) generators tuned to numerous accelerator data including those from the Large Hadron Collider (LHC). We show that the antiproton yields obtained with these MC generators differ by up to an order of magnitude from yields of parameterizations commonly used in astrophysics.

  14. Slow, stopped and stored light

    International Nuclear Information System (INIS)

    Light that can been slowed to walking pace could have applications in telecommunications, optical storage and quantum computing. Whether we use it to estimate how far away a thunderstorm is, or simply take it for granted that we can have a conversation with someone on the other side of the world, we all know that light travels extremely fast. Indeed, special relativity teaches us that nothing in the universe can ever move faster than the speed of light in a vacuum: 299 792 458 ms-1. However, there is no such limitation on how slowly light can travel. For the last few years, researchers have been routinely slowing light to just a few metres per second, and have recently even stopped it dead in its tracks so that it can be stored for future use. Slow-light has considerable popular appeal, deriving perhaps from the importance of the speed of light in relativity and cosmology. If everyday objects such as cars or people can travel faster than 'slow' light, for example, then it might appear that relativistic effects could be observed at very low speeds. Although this is not the case, slow light nonetheless promises to play an important role in optical technology because it allows light to be delayed for any period of time desired. This could lead to all-optical routers that would increase the bandwidth of the Internet, and applications in optical data storage, quantum information and even radar. (U.K.)

  15. 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.

  16. 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....

  17. Bucket shaking stops bunch dancing in Tevatron

    CERN Document Server

    Burov, A

    2012-01-01

    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.

  18. Stopping power of Mylar for heavy ions up to copper

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Annu; Kumar, Shyam E-mail: search@vidja.kuk.ernet.insearch@granth.kuk.ernet.in; Sharma, S.K.; Diwan, P.K.; Nath, N.; Mittal, V.K.; Ghosh, S.; Avasthi, D.K

    2000-10-01

    The stopping powers of Mylar for several heavy ions covering Z=11 to 29 in the energy range {approx}0.3 to 2.3 MeV/n have been measured using the elastic recoil detection technique and twin detector system. The technique provided a unique method to generate a variety of variable energy ion species utilizing a fixed energy 140 MeV Ag{sup 13+} primary beam from the Pelletron accelerator facility at Nuclear Science Center, New Delhi, India. Most of these measurements are new. The experimentally measured stopping power values have been compared with those calculated using LSS theory, Ziegler et al. formulation and Northcliffe and Schilling tabulations. Merits and demerits of these formulations are highlighted. Stopping power calculations using the Hubert et al. formulation have been extended successfully beyond its recommended range of validity, i.e. 2.5-500 MeV/n down to energies as low as 0.5 MeV/n.

  19. 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.

  20. Direct High-Precision Measurement of the g-Factor of a Single Antiproton Stored in a Cryogenic Penning Trap

    CERN Document Server

    Ulmer, S; Blaum, K; Quint, W; Walz, J

    2012-01-01

    We propose a direct high-precision measurement of the magnetic moment, or g-factor, of a single antiproton stored in a cryogenic Penning trap. Currently the most precise value of the magnetic moment of the antiproton is extracted from hyperfine spectroscopy of antiprotonic helium atoms, and known with a relative precision of $10^{-3}$, only . With the experiment proposed in this Letter of Intent we aim at a measurement with a relative precision of $10^{-9}$ or better.

  1. Proceedings of the beam-beam interaction seminar

    International Nuclear Information System (INIS)

    The beam-beam interaction has been and continues to be a performance limiting effect in colliding beam systems. Electron-positron collisions are typically more than a factor of five lower in luminosity than expectations from beam design and with present understanding, extrapolations to future systems are not satisfactory. Prediction and optimized design are even more uncertain for proton-proton and proton-antiproton future systems with the ISR at CERN being the sole precedent. The very health of the high energy physics program in the next decades depends to a significant extent on our ability to unravel the mechanisms of this phenomenon and to control them. There have been a variety of studies, including a plasma model of e+e- collisions, models emphasizing the effects of noise and a model involving a diffusion-damping equilibrium. Various nonlinear analyses of the beam-beam systems have also been performed. And finally an entirely new form of beam-beam configuration has been proposed and studied - the very strong single pass collider. In view of this extensive and broad effort, there was organized an informal seminar to bring many of these ideas into an open forum. This seminar was held at SLAC on May 22 and 23, 1980. Contributors, totaling seventeen, came from universities and national laboratories across the United States. These proceedings represent a record of the seminar. The written versions of the papers presented were submitted by the authors and are included here without editing

  2. A Light Stop with a Heavy Gluino: Enlarging the Stop Gap

    CERN Document Server

    Cleary, Kevin F

    2015-01-01

    It is widely thought that increasing bounds on the gluino mass, which feeds down to the stop mass through renormalization group running, are making a light stop increasingly unlikely. Here we present a counter-example. We examine the case of the Minimal Composite Supersymmetric Standard Model which has a light composite stop. The large anomalous dimension of the stop from strong dynamics pushes the stop mass toward a quasi-fixed point in the infrared, which is smaller than standard estimates by a factor of a large logarithm. The gluino can be about three times heavier than the stop, which is comparable to hierarchy achieved with supersoft Dirac gluino masses. Thus, in this class of models, a heavy gluino is not necessarily indicative of a heavy stop.

  3. Stopping supersonic oxygen with a series of pulsed electromagnetic coils: A molecular coilgun

    OpenAIRE

    Narevicius, Edvardas; Libson, Adam; Parthey, Christian G.; Chavez, Isaac; Narevicius, Julia; Even, Uzi; Raizen, Mark G.

    2008-01-01

    We report the stopping of a molecular oxygen beam, using a series of pulsed electromagnetic coils. A series of coils is fired in a timed sequence to bring the molecules to near-rest, where they are detected with a quadrupole mass spectrometer. Applications to cold chemistry are discussed.

  4. Application of the RADTRAN 5 stop model

    International Nuclear Information System (INIS)

    A number of environmental impact analyses with the RADTRAN computer code have shown that dose to persons at stops is one of the largest components of incident-free dose during overland carriage of spent fuel and other radioactive materials (e.g., USDOE, 1994). The input data used in these analyses were taken from a 1983 study that reports actual observations of spent fuel shipments by truck. Early RADTRAN stop models, however, were insufficiently flexible to take advantage of the detailed information in the study. A more recent study of gasoline service stations that specialize in servicing large trucks, which are the most likely stop locations for shipments of Type B packages in the United States, has provided additional, detailed data on refueling/meal stops. The RADTRAN 5 computer code for transportation risk analysis allows exposures at stops to be more fully modeled than have previous releases of the code and is able to take advantage of detailed data. It is the intent of this paper first to compare results from RADTRAN and RADTRAN 5 for the old, low-resolution form of input data, and then to demonstrate what effect the new data and input format have on stop-dose estimates for an individual stop and for a hypothetical shipment route. Finally, these estimated public doses will be contrasted with doses calculated for a special population group -- inspectors

  5. 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.

  6. Stopping-power calculations for semiconductors

    International Nuclear Information System (INIS)

    The method developed by Brandt and Reinheimer which explicitly includes the effect of the semiconductor gap has been used to calculate the proton and α-particle stopping powers of the valence-electron gas of C (diamond), ZnTe, and U. These values, as well as those existing for Si and Ge, have been combined with the stopping contribution of the electronic core obtained from the statistical atomic model of Bonderup. Stopping powers have also been calculated using the statistical model alone. The calculated curves, which are valid for all incident projectile energies, reproduce the overall features of the semiempirical slowing-down curves, but not always the absolute values

  7. 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.

  8. Collective deceleration: toward a compact beam dump

    OpenAIRE

    Wu, H.-C.; Tajima, T.; Habs, D.; Chao, A.W.; Meyer-ter-Vehn, J.

    2009-01-01

    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 orde...

  9. First observation of two hyperfine transitions in antiprotonic 3He

    International Nuclear Information System (INIS)

    We report on the first experimental results for microwave spectroscopy of the hyperfine structure of p-bar3He+. Due to the helium nuclear spin, p-bar3He+ has a more complex hyperfine structure than p-bar4He+, which has already been studied before. Thus a comparison between theoretical calculations and the experimental results will provide a more stringent test of the three-body quantum electrodynamics (QED) theory. Two out of four super-super-hyperfine (SSHF) transition lines of the (n,L)=(36,34) state were observed. The measured frequencies of the individual transitions are 11.12559(14) GHz and 11.15839(18) GHz, less than 1 MHz higher than the current theoretical values, but still within their estimated errors. Although the experimental uncertainty for the difference of these frequencies is still very large as compared to that of theory, its measured value agrees with theoretical calculations. This difference is crucial to be determined because it is proportional to the magnetic moment of the antiproton.

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

    International Nuclear Information System (INIS)

    A host of dark energy models and nonstandard 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 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 nonstandard cosmologies: a scalar-tensor gravity model, kination models and a Randall-Sundrum D-brane model

  11. Subthreshold antiproton and K- production in heavy ion collisions

    International Nuclear Information System (INIS)

    Subthreshold anti p and K- and energetic π- production was studied in Ne + NaF, Cu, Sn and Bi, and in Ni + Ni collisions with incident energies between 1.6 and 2 GeV/u. The measured cross sections indicate a dominant contribution of baryonic resonances. This is also consistent with a generalized scaling behaviour of the cross sections with the energy available in the collision and the energy necessary to produce particles as observed with Ne induced reactions. Deviations from scaling especially pronounced in the Ni-Ni system will be discussed in terms of absorption effects. The flat slope of the excitation function for anti p production is only understood with a reduced production threshold in the nuclear medium caused by a reduction of the antiproton mass in the dense and heated medium by about 100-150 MeV/c2. A similar in-medium mass reduction is also indicated for K- mesons. The dependence of the anti p yield on the system size is considerably weaker than expected from a simple fireball model, indicating increased reabsorption in Ni + Ni compared to Ne + NaF. (orig.)

  12. Studying the potential of antihyperons in nuclei with antiprotons

    International Nuclear Information System (INIS)

    The interaction between an antibaryon and a nucleus may shed light on the short range antibaryon-baryon force in a unique way. However, because of the deep imaginary part of the nuclear potential of antibaryons, the physics of antihyperons in nuclei is hitherto an uncharted territory. Recently it was proposed to use transverse momentum correlations of exclusively produced antihyperon-hyperon pairs in antiproton-nucleus collisions to obtain information on the antihyperon potentials relative to that of the corresponding hyperon. In the present study we use the Giessen Boltzmann-Uehling- Uhlenbeck Transportmodell (GiBUU) to explore the production of exclusive hyperon-antihyperon pairs close to threshold. Unlike the schematic calculation, these GiBBU simulations take e.g. important rescattering effects into account. In case of anti p + 20Ne → anti ΛΛ+X we confirm a significant sensitivity of transverse momentum correlations to the nuclear potential of Λs. We also explore the feasibility of such measurements at the PANDA experiment of the international facility FAIR.

  13. Near-threshold behavior of positronium-antiproton scattering

    Science.gov (United States)

    Fabrikant, I. I.; Bray, A. W.; Kadyrov, A. S.; Bray, I.

    2016-07-01

    Using the convergent close-coupling theory we study the threshold behavior of cross sections for positronium (Ps) of energy E scattering on antiprotons. In the case of Ps (1 s ) elastic scattering, simple power laws are observed for all partial waves studied. The partial-wave summed cross section is nearly constant, and dominates the antihydrogen formation cross section at all considered energies, even though the latter is exothermic and behaves as 1 /E1 /2 . For Ps (2 s ), oscillations spanning orders of magnitude on top of the 1 /E behavior are found in the elastic and quasielastic cross sections. The antihydrogen formation is influenced by dipole-supported resonances below the threshold of inelastic processes. Resonance energies form a geometric progression relative to the threshold. The exothermic antihydrogen formation cross sections behave as 1 /E at low energies, but are oscillation free. We demonstrate that all these rich features are reproduced by the threshold theory developed by Gailitis [J. Phys. B: At. Mol. Phys. 15, 3423 (1982), 10.1088/0022-3700/15/19/012].

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

    International Nuclear Information System (INIS)

    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.)

  15. Antiproton constraints on dark matter annihilations from internal electroweak bremsstrahlung

    International Nuclear Information System (INIS)

    If the dark matter particle is a Majorana fermion, annihilations into two fermions and one gauge boson could have, for some choices of the parameters of the model, a non-negligible cross-section. Using a toy model of leptophilic dark matter, we calculate the constraints on the annihilation cross-section into two electrons and one weak gauge boson from the PAMELA measurements of the cosmic antiproton-to-proton flux ratio. Furthermore, we calculate the maximal astrophysical boost factor allowed in the Milky Way under the assumption that the leptophilic dark matter particle is the dominant component of dark matter in our Universe. These constraints constitute very conservative estimates on the boost factor for more realistic models where the dark matter particle also couples to quarks and weak gauge bosons, such as the lightest neutralino which we also analyze for some concrete benchmark points. The limits on the astrophysical boost factors presented here could be used to evaluate the prospects to detect a gamma-ray signal from dark matter annihilations at currently operating IACTs as well as in the projected CTA

  16. 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.

  17. Scientists Try to Stop Another Deadly Virus

    Science.gov (United States)

    ... 158128.html Scientists Try to Stop Another Deadly Virus Junin, an Ebola-like disease in Argentina, has ... drug could offer a new weapon against the virus that causes Argentine hemorrhagic fever -- a potentially fatal ...

  18. What Services Are Available to Stop Abuse?

    Science.gov (United States)

    ... Resources Return to: What Communities Can Do What Services Are Available to Stop Abuse? A variety of ... Prosecution of offenders Assistance with obtaining restitution Support Services When abuse or neglect is related to the ...

  19. 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 ...

  20. How to Stop Biting Your Nails

    Medline Plus

    Full Text Available ... Structure Program SPOTme® Skin Cancer Screening Program Volunteer Recognition Program AAD and AADA Historian Leadership Institute Programs ... your fingers and from your nails to your face and mouth. To help you stop biting your ...