Progress on PEP-II injection R ampersand D

International Nuclear Information System (INIS)

Bloom, E.; Bulos, F.; Fieguth, T.; Godfrey, G.; Loew, G.; Miller, R.

1993-06-01

The R ampersand D program described in this paper focuses on an improvement of the SLAC linac designed to extract and study a 9 GeV electron beam under stringent control of energy, energy spread, emittance, optical parameters, and timing. The extraction system begins with an on-axis pulsed magnet, followed by a magnetic lattice and diagnostic equipment required for the measurement and optimization of the above beam qualities. Design, construction, and installation of this system is the first step in the development of the overall PEP-II e ± injection system. This system is required to fill 1658 bunches of 9 GeV electrons (0.99A stored) and 3.1 GeV positrons (2.14A stored) in two separate rings in a total of about 6 minutes from zero ring current (i.e., full-fill mode, 0 to 100%) or in about 3 minutes from 80% ring current (i.e., topping-off mode, 80 to 100%). This unprecedented rate of filling can be met by a judicious use of the SLC linac, damping rings, and positron source

Progress on PEP-II injection R ampersand D

International Nuclear Information System (INIS)

Bloom, E.; Bulos, F.; Fieguth, T.; Godfrey, G.; Loew, G.; Miller, R.

1993-01-01

The R ampersand D program described in this paper focuses on an improvement of the SLAC linac designed to extract and study a 9 GeV electron beam under stringent control of energy, energy spread, emittance, optical parameters, and timing. The extraction system begins with an on-axis pulsed magnet, followed by a magnetic lattice and diagnostic equipment required for the measurement and optimization of the above beam qualities. Design, construction, and installation of this system is the first step in the development of the overall PEP-II e ± injection system. This system is required to fill 1658 bunches of 9 GeV electrons (0.99A stored) and 3.1 GeV positrons (2.14A stored) in two separate rings in a total of about 6 minutes from zero ring current (i.e., full-fill mode, 0 to 100%) or in about 3 minutes from 80% ring current (i.e., topping-off mode, 80 to 100%). This unprecedented rate of filling can be met by a judicious use of the SLC linac, damping rings, and positron source

Status Report on PEP-II Performance

International Nuclear Information System (INIS)

Matter, Regina S.

2002-01-01

PEP-II [1-9] is an e+e- collider with asymmetric energies (3.1 and 9 GeV, respectively) in a 2200 m tunnel at the Stanford Linear Accelerator Center. The collider produces B mesons to study a particle physics effect called CP violation as well as other physics topics. PEP-II was completed in 1998 with the first luminosity generated in July of that year. The installation of the BaBar Detector was finished in May 1999. The overall layout of PEP-II is shown in Figure 1 and the interaction region of PEP-II in Figure 2. The accelerator parameters and achievements of the High Energy Ring (HER) are listed in Table 1 and those for the Low Energy Ring (LER) in Table 2. The two beams collide at a single point in the IR2 hall where the BaBar detector is located. Beam parameters at the best luminosity are shown in Table 3 and PEP-II milestones in Table 4. In August 1999 PEP-II passed the world's record for luminosity which was 8.1x10 32 /cm 2 /s. The present luminosity in PEP-II is 2.15x10 33 /cm 2 /s which is 72% of the design. In June 2000 PEP-II delivered an integrated luminosity of 150 pb -1 in one day, which is above the design integrated luminosity per day of 135 pb -1 . Over the past year PEP-II has delivered over 12 fb -1 to BaBar. BaBar has logged over 11 pb -1 . The present plan is collide until the end of October 2000 followed by a three month installation period

The PEP-II abort kicker system

International Nuclear Information System (INIS)

Lamare, J de; Donaldson, A.; Kulikov, A. Lipari, J.

1997-07-01

The PEP-II project has two storage rings. The HER (High Energy Ring) has up to 1.48 A of electron beam at 9 GeV, and the LER (Low Energy Ring) has up to 2.14 A of positron beam at 3.1 GeV. To protect the HER and LER beam lines in the event of a ring component failure, each ring has an abort kicker system which directs the beam into a dump when a failure is detected. Due to the high current of the beams, the beam kick is tapered from 100% to 80% in 7.33 uS (the beam transit time around the time). This taper distributes the energy evenly across the window which separates the ring from the beam dump such that the window is not damaged. The abort kicker trigger is synchronized with the ion clearing gap of the beam allowing for the kicker field to rise from 0-80% in 370 nS. This report discusses the design of the system controls, interlocks, power supplies, and modulator

Status of the PEP-II B-factory high energy ring

International Nuclear Information System (INIS)

Wienands, U.; Reuter, E.; Bellomo, P.; Daly, E.; Fisher, A.; Gracia, J.; Kulikov, A.; Kurita, N.; Pietryka, M.; Seeman, J.T.; Taylor; Belser, C.; Bertolini, L.; Mugge, M.; Swan, J.

1996-01-01

The 9 GeV High Energy Ring (HER) of the PEP-II B Factory is an electron storage ring under construction at SLAC. Significant progress has been made in the last year on all systems. As of mid 1996, all 192 dipoles have been installed, with installation of the quadrupoles underway. The vacuum system, for design currents up to 3 A average, is in production using a recently commissioned e-beam welder. Beam instrumentation systems are being fabricated. The interaction region will bring the HER beam into collision with the 3 GeV beam of the Low Energy Ring; design of this section of the HER is in an advanced stage. 8 refs., 3 figs., 1 tab

PEP-II RF System Operation and Performance

International Nuclear Information System (INIS)

McIntosh, P.

2005-01-01

The Low Energy Ring (LER) and High Energy Ring (HER) RF systems have operated now on PEP-II since July 1998 and have assisted in breaking all design luminosity records back in June 2001. Luminosity on PEP-II has steadily increased since then as a consequence of larger e+ and e- beam currents being accumulated. This has meant that the RF systems have inevitably been driven harder, not only to achieve these higher stored beam currents, but also to reliably keep the beams circulating whilst at the same time minimizing the number of aborts due to RF system faults. This paper details the current PEP-II RF system configurations for both rings, as well as future upgrade plans spanning the next 3-5 years. Limitations of the current RF system configurations are presented, highlighting improvement projects which will target specific areas within the RF systems to ensure that adequate operating overheads are maintained and reliable operation is assured. The Low Energy Ring (LER) and High Energy Ring (HER) RF systems have operated now on PEP-II since July 1998 and have assisted in breaking all design luminosity records back in June 2001. Luminosity on PEP-II has steadily increased since then as a consequence of larger e+ and e- beam currents being accumulated. This has meant that the RF systems have inevitably been driven harder, not only to achieve these higher stored beam currents, but also to reliably keep the beams circulating whilst at the same time minimizing the number of aborts due to RF system faults. This paper details the current PEP-II RF system configurations for both rings, as well as future upgrade plans spanning the next 3-5 years. Limitations of the current RF system configurations are presented, highlighting improvement projects which will target specific areas within the RF systems to ensure that adequate operating overheads are maintained and reliable operation is assured

Luminosity upgrade possibilities for the PEP-II B-Factory

CERN Document Server

Sullivan, M

2003-01-01

PEP-II is an asymmetric e sup + e sup - collider being constructed in the SLAC PEP tunnel by SLAC, LBNL, and LLNL. The two beams have energies of 3.1 GeV and 9.0 GeV and are made to collide at a single interaction point. PEP-II has a 2200 m circumference. The nominal parameters for PEP-II are listed in Table 1. The High Energy Ring (HER) of PEP-II started commissioning in 1997. The Low Energy Ring (LER) will be commissioned in the summer of 1998. The BaBar detector is to be installed starting January 1999. Studies for increasing the luminosity in PEP-II beyond the design are underway. A brief summary of the possibilities are presented here. Improvements to the integrated luminosity will be implemented gradually. Major luminosity improvements will likely come in two phased upgrades. Several of these possibilities are summarized in Table 1.

LUMINOSITY UPGRADE POSSIBILITIES FOR THE PEP-II B-FACTORY

International Nuclear Information System (INIS)

Sullivan, Michael K

2003-01-01

PEP-II is an asymmetric e + e - collider being constructed in the SLAC PEP tunnel by SLAC, LBNL, and LLNL. The two beams have energies of 3.1 GeV and 9.0 GeV and are made to collide at a single interaction point. PEP-II has a 2200 m circumference. The nominal parameters for PEP-II are listed in Table 1. The High Energy Ring (HER) of PEP-II started commissioning in 1997. The Low Energy Ring (LER) will be commissioned in the summer of 1998. The BaBar detector is to be installed starting January 1999. Studies for increasing the luminosity in PEP-II beyond the design are underway. A brief summary of the possibilities are presented here. Improvements to the integrated luminosity will be implemented gradually. Major luminosity improvements will likely come in two phased upgrades. Several of these possibilities are summarized in Table 1

The PEP-II Asymmetric B Factory: Design details and R ampersand D results

International Nuclear Information System (INIS)

Bloom, E.; DeStaebler, H.; Dorfan, J.

1994-06-01

PEP-II, a 9 GeV x 3.1 GeV electron-positron collider with a design luminosity of 3 x 10 33 cm -2 s -1 has now been approved for construction by SLAC, LBL and LLNL for the purpose of studying CP violation in the B bar B system. This upgrade project involves replacing the vacuum and RF systeum of PEP, which will serve as the high-energy ring (HER), along with the addition of a new low-energy ring (LER) mounted atop the HER. Designs for both rings are described, and the anticipated project construction schedule is indicated. Collider operation will begin at the end of 1998. An aggressive R ampersand D program has been carried out to validate our design choices; key results in the areas of lattice design, vacuum, RF, and multibunch feedback are summarized

Analysis of the wake field effects in the PEP-II storage rings with extremely high currents

Energy Technology Data Exchange (ETDEWEB)

Novokhatski, A., E-mail: novo@slac.stanford.edu; Seeman, J.; Sullivan, M.

2014-01-21

We present the history and analysis of different wake field effects throughout the operational life of the PEP-II SLAC B-factory. Although the impedance of the high and low energy rings is small, the intense high-current beams generated a lot of power. The effects from these wake fields are: heating and damage of vacuum beam chamber elements like RF seals, vacuum valves, shielded bellows, BPM buttons and ceramic tiles; vacuum spikes, vacuum instabilities and high detector background; and beam longitudinal and transverse instabilities. We also discuss the methods used to eliminate these effects. Results of this analysis and the PEP-II experience may be very useful in the design of new storage rings and light sources.

Modeling and Simulation of Longitudinal Dynamics for Low Energy Ring-High Energy Ring at the Positron-Electron Project

International Nuclear Information System (INIS)

Rivetta, Claudio; Mastorides, T.; Fox, J.D.; Teytelman, D.; Van Winkle, D.

2007-01-01

A time domain dynamic modeling and simulation tool for beam-cavity interactions in the Low Energy Ring (LER) and High Energy Ring (HER) at the Positron-Electron Project (PEP-II) is presented. Dynamic simulation results for PEP-II are compared to measurements of the actual machine. The motivation for this tool is to explore the stability margins and performance limits of PEP-II radio-frequency (RF) systems at future higher currents and upgraded RF configurations. It also serves as a test bed for new control algorithms and can define the ultimate limits of the low-level RF (LLRF) architecture. The time domain program captures the dynamic behavior of the beam-cavity-LLRF interaction based on a reduced model. The ring current is represented by macrobunches. Multiple RF stations in the ring are represented via one or two macrocavities. Each macrocavity captures the overall behavior of all the 2 or 4 cavity RF stations. Station models include nonlinear elements in the klystron and signal processing. This enables modeling the principal longitudinal impedance control loops interacting via the longitudinal beam model. The dynamics of the simulation model are validated by comparing the measured growth rates for the LER with simulation results. The simulated behavior of the LER at increased operation currents is presented via low-mode instability growth rates. Different control strategies are compared and the effects of both the imperfections in the LLRF signal processing and the nonlinear drivers and klystrons are explored

Measurements of the Electron Cloud Density in the PEP-II Low Energy Ring

Energy Technology Data Exchange (ETDEWEB)

Byrd, John; De Santis, Stefano; Sonnad, Kiran; Caspers, Fritz; Kroyer, Tom; Krasnykh, Anatoly; Pivi, Mauro

2008-06-01

Clouds of low energy electronsin the vacuum beam pipes of accelerators of positively charged particle beams present a serious limitation for operation of these machines at high currents. Because of the size of these accelerators, it is difficult to probe the low energyelectron clouds over substantial lengths of the beam pipe. We have developed a novel technique to directly measure the electron cloud density via the phase shift induced in a TE wave that is independently excited and transmitted over a section of the accelerator. We infer the absolute phase shift with relatively high accuracy from the phase modulation of the transmission due to the modulation of the electron cloud density from a gap in the positively charged beam. We have used this technique for the first time to measure the average electron cloud density over a 50 m straight section in the positron ring of the PEP-II collider at the Stanford Linear Accelerator Center. We have also measured the variation of the density by using low field solenoid magnets to control the electrons.

KEKB and PEP-II B Factories

International Nuclear Information System (INIS)

Seeman, J.T.

1997-01-01

Two asymmetric B-Factories KEKB at KEK and PEP-II at SLAC are under construction, designed to study CP violation in the b-quark sector with a center of mass energy of 10.58 GeV. These two new accelerators are high luminosity two-ring two-energy e + e - colliders with one interaction point. There are many challenging accelerator physics and engineering issues associated with the high beam currents and high luminosities of these rings. The chosen solutions to these issues and the general parameters of the two rings are described in detail side-by-side. KEKB and PEP-II are well into the installation phase and are both scheduled to be completed in 1998. The particle physics programs are scheduled to start in 1999

BERKELEY: Collaboration on PEP-II

International Nuclear Information System (INIS)

Anon.

1995-01-01

Since the announcement by President Clinton in October 1993 that the US Department of Energy would going ahead the PEPII Asymmetric B Factory project (a joint proposal of the Stanford Linear Accelerator Center - SLAC, the Lawrence Berkeley National Laboratory - LBNL, and the Lawrence Livermore National Laboratory - LLNL), LBNL has continued its strong support of the project (for a review, see October, page 9). LBNL accelerator physicists have been active in the design of PEP-II since 1988 - shortly after the original concept was suggested by LBNL Deputy Director Pier Oddone. Indeed, the original feasibility study for such a machine was a joint LBNLSLAC- Caltech effort led by Swapan Chattopadhyay, now head of LBNL's Center for Beam Physics (CBP) in the Accelerator & Fusion Research Division (AFRD). The effort grew to include about seven full-time LBNL accelerator physicists (along with about 15 SLAC and LLNL physicists) during the formal design phase, which began in late 1989. This effort encompassed three editions of the Conceptual Design Report, along with innumerable reviews, as is typical of today's accelerator projects. Taking advantage of an experienced engineering staff, fresh from the successful completion of the Advanced Light Source (ALS), LBNL has been assigned lead responsibility for the challenging Low Energy Ring (LER) of the PEP-II project, an entirely new storage ring to be added to the PEP tunnel. The LBNL design team is headed by CBP accelerator physicist Michael Zisman and senior engineers Ron Yourd (who served as the Project Manager for the ALS) and Hank Hsieh (a recent addition to the LBNL staff who was Project Engineer for the NSLS storage rings at BNL and most recently served as Project Engineer for the DAFNE project at Frascati). LBNL is also represented in the overall management of the PEP-II project by Tom Elioff, who serves as Deputy to the Project Director Jonathan Dorfan at SLAC. (Elioff served in the same role for the original

Experimental Observations of In-Situ Secondary Electron Yield Reduction in the PEP-II Particle Accelerator Beam Line

International Nuclear Information System (INIS)

Pivi, Mauro

2010-01-01

Beam instability caused by the electron cloud has been observed in positron and proton storage rings and it is expected to be a limiting factor in the performance of the positron Damping Ring (DR) of future Linear Colliders (LC) such as ILC and CLIC. To test a series of promising possible electron cloud mitigation techniques as surface coatings and grooves, in the Positron Low Energy Ring (LER) of the PEP-II accelerator, we have installed several test vacuum chambers including (i) a special chamber to monitor the variation of the secondary electron yield of technical surface materials and coatings under the effect of ion, electron and photon conditioning in situ in the beam line; (ii) chambers with grooves in a straight magnetic-free section; and (iii) coated chambers in a dedicated newly installed 4-magnet chicane to study mitigations in a magnetic field region. In this paper, we describe the ongoing R and D effort to mitigate the electron cloud effect for the LC damping ring, focusing on the first experimental area and on results of the reduction of the secondary electron yield due to in situ conditioning.

Study of coupled-bunch collective effects in the PEP-II B-Factory

International Nuclear Information System (INIS)

Byrd, J.

1993-05-01

We present an overview of the calculated longitudinal and transverse coupled-bunch (CB) growth using the measured RF cavity higher order mode impedance and estimated resistive wall (RW) impedance for the proposed PEP-II B-Factory, a dual-ring electron-positron collider. We also describe a visual method of representing the effective beam impedance and corresponding growth rates which is especially useful for understanding the dependence of growth rate on higher order mode frequency and Q, spread of HOM frequencies between cells, and for determining the requirements of the CB feedback systems

Observation of magnetic resonances in electron clouds in a positron storage ring

International Nuclear Information System (INIS)

Pivi, M.T.F.; Ng, J.S.T.; Cooper, F.; Kharakh, D.; King, F.; Kirby, R.E.; Kuekan, B.; Spencer, C.M.; Raubenheimer, T.O.; Wang, L.F.

2010-01-01

The first experimental observation of magnetic resonances in electron clouds is reported. The resonance was observed as a modulation in cloud intensity for uncoated as well as TiN-coated aluminum surfaces in the positron storage ring of the PEP-II collider at SLAC. Electron clouds frequently arise in accelerators of positively charged particles, and severely impact the machines' performance. The TiN coating was found to be an effective remedy, reducing the cloud intensity by three orders of magnitude.

A New Chicane Experiment In PEP-II to Test Mitigations of the Electron Cloud Effect for Linear Colliders

International Nuclear Information System (INIS)

Pivi, M

2008-01-01

Beam instability caused by the electron cloud has been observed in positron and proton storage rings, and it is expected to be a limiting factor in the performance of future colliders [1-3]. The effect is expected to be particularly severe in magnetic field regions. To test possible mitigation methods in magnetic fields, we have installed a new 4-dipole chicane experiment in the PEP-II Low Energy Ring (LER) at SLAC with both bare and TiN-coated aluminum chambers. In particular, we have observed a large variation of the electron flux at the chamber wall as a function of the chicane dipole field. We infer this is a new high order resonance effect where the energy gained by the electrons in the positron beam depends on the phase of the electron cyclotron motion with respect to the bunch crossing, leading to a modulation of the secondary electron production. Presumably the cloud density is modulated as well and this resonance effect could be used to reduce its magnitude in future colliders. We present the experimental results obtained during January 2008 until the April final shut-down of the PEP-II machine

Secondary Electron Emission Yields from PEP-II Accelerator Materials

International Nuclear Information System (INIS)

Kirby, Robert E.

2000-01-01

The PEP-II B-Factory at SLAC operates with aluminum alloy and copper vacuum chambers, having design positron and electron beam currents of 2 and 1 A, respectively. Titanium nitride coating of the aluminum vacuum chamber in the arcs of the positron ring is needed in order to reduce undesirable electron-cloud effects. The total secondary electron emission yield of TiN-coated aluminum alloy has been measured after samples of beam chamber material were exposed to air and again after electron-beam bombardment, as a function of incident electron beam angle and energy. The results may be used to simulate and better understand electron-cloud effects under actual operating conditions. We also present yield measurements for other accelerator materials because new surface effects are expected to arise as beam currents increase. Copper, in particular, is growing in popularity for its good thermal conductivity and self-radiation-shielding properties. The effect of electron bombardment, ''conditioning'', on the yield of TiN and copper is shown

Performance of the PEP-II B-Factory Collider at SLAC

International Nuclear Information System (INIS)

Seeman, J.; Browne, M.; Cai, Y.; Colocho, W.; Decker, F.J.; Donald, M.H.; Ecklund, S.; Erickson, R.A.; Fisher, A.S.; Fox, J.D.; Heifets, S.A.; Iverson, R.H.; Kulikov, A.; Li, N.; Novokhatski, A.; Ross, M.C.; Schuh, P.; Smith, T.J.; Sonnad, K.G.; Stanek, M.; Sullivan, M.K.

2006-01-01

PEP-II is an e + e - asymmetric B-Factory Collider located at SLAC operating at the Upsilon 4S resonance (3.1 GeV x 9 GeV). It has reached a luminosity of 9.21 x 10 33 /cm 2 /s and has delivered an integrated luminosity of 710 pb -1 in one day. PEP-II has delivered, over the past six years, an integrated luminosity to the BaBar detector of over 262 fb -1 . PEP-II operates in continuous injection mode for both beams boosting the integrated luminosity. The peak positron current has reached 2.45 A in 1588 bunches. Steady progress is being made in reaching higher luminosity. The goal over the next several years is to reach a luminosity of 2.1 x 10 34 /cm 2 /s. The accelerator physics issues being addressed in PEP-II to reach this goal include the electron cloud instability, beam-beam effects, parasitic beam-beam effects, high RF beam loading, shorter bunches, lower β* y interaction region operation, and coupling control. Figure 1 shows the PEP-II tunnel

Storage rings, internal targets and PEP

International Nuclear Information System (INIS)

Spencer, J.E.

1986-11-01

Storage rings with internal targets are described, using PEP as an example. The difference between electrons and heavier particles such as protons, antiprotons, and heavy ions is also discussed because it raises possibilities of bypass insertions for more exotic experiments. PEP is compared to other rings in various contexts to verify the assertion that it is an ideal ring for many fundamental and practical applications that can be carried on simultaneously

The vacuum system for the PEP II high energy ring straight sections

International Nuclear Information System (INIS)

Wienands, U.; Daly, E.; Heifets, S.A.; Kulikov, A.; Kurita, N.; Nordby, M.; Perkins, C.; Reuter, E.; Seeman, J.T.; Belser, F.C.; Berg, J.; Holdener, F.R.; Kerns, J.A.; McDaniel, M.R.; Stoeffl, W.

1995-01-01

The six straight sections of the PEP II High Energy Ring (HER) serve various functions: lattice tuning, beam injection and abort, providing space for rf cavities, longitudinal and transverse feedback, beam diagnostics and the interaction point. A stainless steel vacuum system has been designed; prototypes are currently being built. Cooling is required due to radiation coming from the last arc dipole and resistive losses in the vacuum chamber. Although the nominal beam current of the HER is 1 A the vacuum system is designed for 3 A to provide margin and an upgrade path. 5 refs., 7 figs

Observation of Beam Size Flip-Flop in PEP-II

International Nuclear Information System (INIS)

Holtzapple, Robert luther

2002-01-01

The asymmetric B-factory, PEP-II, has delivered a peak luminosity of 4.6 x 10 33 cm -2 s -1 with less than half the design number of bunches, requiring a luminosity per bunch crossing more than three times larger than the design. As a result, strong beam-beam effects are present. The strong beam-beam forces between colliding electron and positron bunches can result in a ''flip-flop'' of the transverse beam size of some bunches. Focusing on one positron-electron colliding bunch pair, a flip-flop occurs when the transverse size of the positron bunch shrinks and the electron bunch grows. The flip-flop accounts for a reduction in luminosity, a lower positron lifetime, and increased background in the BABAR detector. The flip-flop phenomenon occurs not for all of the colliding bunches, but for the bunches at the front of a mini-train. Once a colliding pair has flipped to its reduced luminosity state it can be changed back to its normal state by raising the horizontal tune in the low-energy ring (LER, positrons) by 0.01. Afterwards the LER x-tune can be reduced nearly back to its original point, resulting in higher luminosity. These observations were verified and quantified with a new time-gated camera with a resolution of 2 ns, making it possible to observe single bunches

An Over-damped Cavity Longitudinal Kicker for the PEP-II LER

CERN Document Server

McIntosh, P

2003-01-01

Both rings of PEP-II use drift tube kickers in the longitudinal bunch-by-bunch feedback system. Efforts are now underway to increase the stored beam currents and luminosity of PEP-II, and beam-induced heating of these structures, particularly in the Low Energy Ring (LER) is of concern. An alternative kicker design based on the over-damped cavity kicker, first developed by INFN-Frascati is being built for PEP-II. This low loaded Q (or wide bandwidth) structure is fed by a network of ridged waveguides coupled to a simple pill-box cavity. Beam induced RF power is also coupled out of the cavity to external loads, so that the higher order modes (HOMs) excited in the structure are well-damped. This paper details the kicker design for PEP-II and discusses some of the design trade-offs between shunt impedance and bandwidth, as well as the influence of the feedthroughs on the kicker parameters. Estimates of the expected power deposition in the cavity are also provided.

PEP-II prototype klystron

International Nuclear Information System (INIS)

Fowkes, W.R.; Caryotakis, G.; Lee, T.G.; Pearson, C.; Wright, E.L.

1993-04-01

A 540-kW continuous-wave (cw) klystron operating at 476 MHz was developed for use as a power source for testing PEP-II rf accelerating cavities and rf windows. It also serves as a prototype for a 1.2 MW cw klystron presently being developed as a potential rf source for asymmetric colliding ring use. The design incorporates the concepts and many of the parts used in the original 353 MHz PEP klystron developed sixteen years ago. The superior computer simulation codes available today result in improved performance with the cavity frequencies, drift lengths, and output circuit optimized for the higher frequency.The design and operating results of this tube are described with particular emphasis on the factors which affect efficiency and stability

A test of planar spark counters at the PEP storage ring

International Nuclear Information System (INIS)

Atwood, W.B.; Bowden, G.B.; Bonneaud, G.R.; Klem, D.E.; Ogawa, A.; Pestov, Yu.N.; Pitthan, R.; Sugahara, R.

1983-01-01

A test of planar spar counters (PSCs) at the PEP electron-positron storage ring showed the following. PSCs can be used under harsh experimental conditions without long term degradation of resolution. On-line time-of-flight resolutions were below 200 ps, coordinate resolutions better than 4 mm, both limited to these values by the resistivity of the semiconducting glass and the electronics used. The best single counter time resolution under realistic conditions at the storage ring was 76 ps. Pulse height was a good indicator of the number of particles striking a counter. Subsequent measurements using cosmis rays gave a single counter time resolution of 50 ps. (orig.)

The PEP II injection kicker system

International Nuclear Information System (INIS)

Pappas, G.C.; Donaldson, A.R.; Williams, D.

1997-07-01

PEP II or the B Factory consists of two asymmetric storage rings. The injection energy for electrons is 9 GeV, while that for positrons is 3.1 GeV. The bend angle into the high energy ring (HER) is 0.35 m-rad, and the angle into the low energy ring (LER) is 0.575 m-rad. The magnetic length for the HER kicker is 0.85 m, and 0.55 m for the LER kicker. The field produced by the magnet is therefore 123.5 G for the HER, and 132 G for the LER. Each ring has a kicker magnet upstream of the injection line which is used to distort the orbit of the stored beam. An identical magnet downstream of the injection line is used to restore the orbit of the stored beam and inject the incoming beam. The two magnets are driven in parallel by the modulator. The apeture of the magnets is 3.86x3.46 cm (HxV). Therefore the current required to drive the HER is 863 A, while for the LER it is 756 A. The inductance of the magnet is approximately 1.4 uH/m. The current pulse is a critically damped sinusoid with a rise time of less than 300 ns. A kicker system has been designed which can be used for injection of both beams by varying the charge of voltage. The modulator uses a conjugate circuit to match the impedance of the magnet, and coupling to the beam chamber

Low energy ring lattice of the PEP-II asymmetric B-Factory

International Nuclear Information System (INIS)

Cai, Y.; Donald, M.; Helm, R.; Irwin, J.; Nosochkov, Y.; Ritson, D.M.; Yan, Y.

1995-01-01

Developing a lattice that contains a very low beta value at the interaction point (IP) and has adequate dynamic aperture is one of the major challenges in designing the PEP-II asymmetric B-factory. For the Low Energy Ring (LER) the authors have studied several different chromatic correction schemes since the conceptual design report (CDR). Based on these studies, a hybrid solution with local and semi-local chromatic sextupoles has been selected as the new baseline lattice to replace the local scheme in the CDR. The new design simplifies the interaction region (IR) and reduces the number of sextupoles in the arcs. Arc sextupoles are paired at π phase difference and are not interleaved. In this paper the authors describe the baseline lattice with the emphasis on the lattice changes made since the CDR

Progress of the PEP-II B-factory

International Nuclear Information System (INIS)

Seeman, J.; Browne, M.; Cai, Y.; Colocho, W.; Decker, F.-J.; Donald, M.; Ecklund, S.; Erickson, R.; Fisher, A.; Fox, J.; Heifets, S.; Iverson, R.; Kozanecki, W.; Krejcik, P.; Kulikov, A.; Novokhatski, A.; Schuh, P.; Schwarz, H.; Stanek, M.; Sullivan, M.; Teytelman, D.; Turner, J.; Wienands, U.; Yan, Y.; Yocky, J.; Biagini, M.; Zisman, M.

2003-01-01

PEP-II is an e + e - B-Factory Collider located at SLAC operating at the Upsilon 4S resonance. PEP-II has delivered, over the past five years, an integrated luminosity to the BaBar detector of over 139 fb -1 and has reached a luminosity of 6.58 x 10 36 /cm 2 /s. Steady progress is being made in reaching higher luminosity. The goal over the next several years is to reach a luminosity of at least 2 x 10 34 /cm 2 /s. The accelerator physics issues being addressed in PEP-II to reach this goal include the electron cloud instability, beam-beam effects, parasitic beam-beam effects, high RF beam loading, shorter bunches, lower beta y*, interaction region operation, and coupling control. A view of the PEP-II tunnel is shown in Figure 1. The present parameters of the PEP-II B-Factory are shown in Table 1 compared to the design. The present peak luminosity is 219% of design and the best integrated luminosity per month is 7.4 fb -1 that is 225% of design. The best luminosity per month is shown in Figure 2. The integrated luminosity over a month is shown in Figure 3 and the total integrated luminosity in shown in Figure 4. The progress in luminosity has come from correcting the orbits, adding specific orbit bumps to correct coupling and dispersion issues, lowering the beta y* in the LER, and moving the fractional horizontal tunes in both rings to just above the half integer (<0.52)

Optical distortions in electron/positron storage rings

International Nuclear Information System (INIS)

Brown, K.L.; Donald, M.; Servranckx, R.

1983-01-01

We have studied the optical distortions in the PEP electron/positron storage ring for various optical configurations using the computer programs DIMAT, HARMON, PATRICIA, and TURTLE. The results are shown graphically by tracing several thousand trajectories from one interaction region to the next using TURTLE and by tracing a few selected rays several hundred turns using the programs DIMAT and PATRICIA. The results show an interesting correlation between the calculated optical cleanliness of a particular lattice configuration and the observed operating characteristics of the machine

An asymmetric B factory based on PEP

International Nuclear Information System (INIS)

1991-02-01

In this report we describe a design for a high-luminosity Asymmetric B Factory to be built in the PEP tunnel on the SLAC site. This proposal, a collaborative effort SLAC, LBL, and LLNL, is the culmination of more than two years of effort aimed at the design and construction of an asymmetric e + e - collider capable of achieving a luminosity of L = 3 x 10 33 cm -2 s -1 . The configuration adopted utilizes two storage rings, and electron ring operating at 9 GeV and a positron ring at 3.1 GeV, each with a circumference of 2200 m. The high-energy ring is an upgrade of the PEP storage ring at SLAC; all PEP magnets and most power supplies will be reused. The upgrade consists primarily of replacing the PEP vacuum chamber and RF system with newly designed versions optimized for the high-current environment of the B Factory. The low-energy ring will be newly constructed and will be situated atop the high-energy ring in the PEP tunnel. Utilities already installed in the PEP tunnel are largely sufficient to operate the two B Factory storage rings

Muon shielding for PEP

International Nuclear Information System (INIS)

Jenkins, T.M.; Thomas, R.H.

1974-01-01

The first stage of construction of PEP will consist of electron and positron storage rings. At a later date a 200 GeV proton storage ring may be added. It is judicious therefore, to ensure that the first and second phases of construction are compatible with each other. One of several factors determining the elevation at which the storage rings will be constructed is the necessity to provide adequate radiation shielding. The overhead shielding of PEP is determined by the reproduction of neutrons in the hadron cascade generated by primary protons lost from the storage ring. The minimum overburden planned for PEP is 5.5 meters of earth (1100 gm cm/sup /minus/2/). To obtain a rough estimate of the magnitude of the muon radiation problem this note presents some preliminary calculations. Their purpose is intended merely to show that the presently proposed design for PEP will present no major shielding problems should the protons storage ring be installed. More detailed calculations will be made using muon yield computer codes developed at CERN and NAL and muon transport codes developed at SLAC, when details of the proton storage ring become settled. 9 refs., 4 figs

PEP talk

International Nuclear Information System (INIS)

Anon.

1980-01-01

The newly operating PEP electron-positron storage ring, built by the Berkeley and Stanford Laboratories, was dedicated on 5 September. PEP comes on with some unusual handicaps. It is of course competing with PETRA at DESY. It is late and it will take all the ingenuity and imagination that this great Lab, with its great traditions, can muster to catch up and show the world that US physics is strong and that the large funds vested here are well spent

An asymmetric B factory based on PEP

Energy Technology Data Exchange (ETDEWEB)

1991-02-01

In this report we describe a design for a high-luminosity Asymmetric B Factory to be built in the PEP tunnel on the SLAC site. This proposal, a collaborative effort SLAC, LBL, and LLNL, is the culmination of more than two years of effort aimed at the design and construction of an asymmetric e{sup +}e{sup {minus}} collider capable of achieving a luminosity of L = 3 {times} 10{sup 33} cm{sup {minus}2} s{sup {minus}1}. The configuration adopted utilizes two storage rings, and electron ring operating at 9 GeV and a positron ring at 3.1 GeV, each with a circumference of 2200 m. The high-energy ring is an upgrade of the PEP storage ring at SLAC; all PEP magnets and most power supplies will be reused. The upgrade consists primarily of replacing the PEP vacuum chamber and RF system with newly designed versions optimized for the high-current environment of the B Factory. The low-energy ring will be newly constructed and will be situated atop the high-energy ring in the PEP tunnel. Utilities already installed in the PEP tunnel are largely sufficient to operate the two B Factory storage rings.

Transverse feedback systems for the PEP-II B-factory

International Nuclear Information System (INIS)

Corlett, J.N.; Barry, W.; Byrd, J.M.; Lambertson, G.; Johnson, J.; Fahmie, M.

1995-10-01

Growth rates of coherent beam oscillations are faster than the natural damping mechanisms for the parameters of the PEP-II B-factory storage rings at nominal currents, even with damping of cavity higher order modes (HOM's). With 165 8 bunches separated by 4.2 ns, and a large current of up to 3A (2.14 A nominal in the low energy ring), many coupled-bunch modes are excited by the resistive wall impedance and cavity higher order mode impedance. Fastest growth times of transverse rigid-bunch modes of approximately 300 ps are expected, two orders of magnitude faster than the radiation damping time. We will provide broadband, bunch-by-bunch feedback to suppress this coherent motion of the beam. Experience gained with a prototype system, installed and successfully operating at the LBNL Advanced Light Source (ALS), has been used extensively in developing the design of the PEP-II systems

Commissioning the beam diagnostics for the PEP-II B Factory

International Nuclear Information System (INIS)

Fisher, A.S.; Alzofon, D.; Collins, B.

1998-06-01

PEP-II is a 2.2-km-circumference collider with a 2.1-A, 3.1-GeV positron ring (the Low-Energy Ring) 1 m above a 1-A, 9-GeV electron ring (the High-Energy Ring); both rings are designed for a maximum current of 3 A. The authors describe the beam diagnostics and present measurements from HER commissioning. The beam profile is measured using near-UV synchrotron light extracted by grazing-incidence mirrors that must withstand up to 200 W/cm. Normally 1,658 of the 3,492 buckets will be filled, and the charge must be equal within 2%. To measure the charge in each bucket, the sum signal from a set of 4 pickup buttons is digitized and averaged over 256 samples per bucket in every 60-Hz interval. The sum is them normalized to the ring current, measured by a DC current transformer. The 300 beam-position monitors per ring are multiplexed to share 171 processor modules, which use DPSs for recording positions over 1,024 turns and for calibration. For both diagnostics and machine protection, 100 photomultipliers with fused-silica Cherenkov radiators measure beam losses and can trigger a beam abort in case of high loss. For the ring tunes, signals from a set of 4 pickup buttons are combined into horizontal, vertical, and sum signals. Two signals are selected and downconverted into the range of a 10-MHz, 2-channel, programmable, DSP-based spectrum analyzer, connected over ethernet to the control room

Upgrades to PEP-II Tune Measurements

Energy Technology Data Exchange (ETDEWEB)

Fisher, Alan S.

2002-07-30

The tune monitors for the two-ring PEP-II collider convert signals from one set of four BPM-type pickup buttons per ring into horizontal and vertical differences, which are then downconverted from 952 MHz (twice the RF) to baseband. Two-channel 10-MHz FFT spectrum analyzers show spectra in X-window displays in the Control Room, to assist PEP operators. When operating with the original system near the beam-beam limit, collisions broadened and flattened the tune peaks, often bringing them near the noise floor. We recently installed new downconverters that increase the signal-to-noise ratio by about 5 dB. In addition, we went from one to two sets of pickups per ring, near focusing and defocusing quadrupoles, so that signals for both planes originate at locations with large amplitudes. We also have just installed a tune tracker, based on a digital lock-in amplifier (one per tune plane) that is controlled by an EPICS software feedback loop. The tracker monitors the phase of the beam's response to a sinusoidal excitation, and adjusts the drive frequency to track the middle of the 1 go-degree phase transition across the tune resonance. We plan next to test an outer loop controlling the tune quadrupoles based on this tune measurement.

Upgrades to PEP-II Tune Measurements

Energy Technology Data Exchange (ETDEWEB)

Fisher, Alan S.

2002-07-30

The tune monitors for the two-ring PEP-II collider convert signals from one set of four BPM-type pickup buttons per ring into horizontal and vertical differences, which are then downconverted from 952 MHz (twice the RF) to baseband. Two-channel l0-MHz FFT spectrum analyzers show spectra in X-window displays in the Control Room, to assist PEP operators. When operating with the original system near the beam-beam limit, collisions broadened and flattened the tune peaks, often bringing them near the noise floor. We recently installed new downconverters that increase the signal-to-noise ratio by about 5 dB. In addition, we went from one to two sets of pickups per ring, near focusing and defocusing quadrupoles, so that signals for both planes originate at locations with large amplitudes. We also have just installed a tune tracker, based on a digital lock-in amplifier (one per tune plane) that is controlled by an EPICS software feedback loop. The tracker monitors the phase of the beam's response to a sinusoidal excitation, and adjusts the drive frequency to track the middle of the 180-degree phase transition across the tune resonance. We plan next to test an outer loop controlling the tune quadrupoles based on this tune measurement.

Upgrades to PEP-II tune measurements

International Nuclear Information System (INIS)

Fisher, Alan S.; Petree, Mark; Wienands, Uli; Allison, Stephanie; Laznovsky, Michael; Seeman, Michael; Robin, Jolene

2002-01-01

The tune monitors for the two-ring PEP-II collider convert signals from one set of four BPM-type pickup buttons per ring into horizontal and vertical differences, which are then downconverted from 952 MHz (twice the RF) to baseband. Two-channel 10-MHz FFT spectrum analyzers show spectra in X-window displays in the Control Room, to assist PEP operators. When operating with the original system near the beam-beam limit, collisions broadened and flattened the tune peaks, often bringing them near the noise floor. We recently installed new downconverters that increase the signal-to-noise ratio by about 5 dB. In addition, we went from one to two sets of pickups per ring, near focusing and defocusing quadrupoles, so that signals for both planes originate at locations with large amplitudes. We also have just installed a tune tracker, based on a digital lock-in amplifier (one per tune plane) that is controlled by an EPICS software feedback loop. The tracker monitors the phase of the beam's response to a sinusoidal excitation, and adjusts the drive frequency to track the middle of the 180-degree phase transition across the tune resonance. We plan next to test an outer loop controlling the tune quadrupoles based on this tune measurement

Lattice Effects Due to High Currents in PEP-II

International Nuclear Information System (INIS)

Decker, F.-J.; Smith, H.; Turner, J.L.; SLAC

2005-01-01

The very high beam currents in the PEP-II B-Factory have caused many expected and unexpected effects: Synchrotron light fans move the beam pipe and cause dispersion; higher order modes cause excessive heating, e-clouds around the positron beam blow up its beam size. Here we describe an effect where the measured dispersion of the beam in the Low Energy Ring (LER) is different at high and at low beam currents. The dispersion was iteratively lowered by making anti-symmetric orbit bumps in many sextupole duplets, checking each time with a dispersion measurement where a dispersive kick is generated. This can be done parasitically during collisions. It was a surprise when checking the low current characterization data that there is a change. Subsequent high and low current measurements confirmed the effect. One source was believed to be located far away from any synchrotron radiation in the middle of a straight (PR12), away from sextupoles and skew quadrupoles and created a dispersion wave of about 70 mm at high current while at low current it is negligible

Bunch-by-bunch feedback for PEP II

International Nuclear Information System (INIS)

Oxoby, G.; Claus, R.; Eisen, N.; Fox, J.; Hindi, H.; Hoeflich, J.; Olsen, J.; Sapozhnikov, L.; Linscott, I.

1993-01-01

The proposed PEP II B factory at SLAC requires a feedback to damp out longitudinal synchrotron oscillations. A time domain, downsampled, bunch-by-bunch feedback system in which each bunch is treated as an oscillator being driven by disturbances from other bunches is presented as we review the evolution of the system design. Results from a synchrotron oscillation damping experiment conducted at the SLAC/SSRL/SPEAR ring are also presented in this paper

Design features and operational characteristics of the PEP beam-transport and injection system

International Nuclear Information System (INIS)

Peterson, J.M.; Brown, K.L.; Truher, J.B.

1981-03-01

The PEP beam-transport system was designed to transmit 4-to-15 GeV electron and positron beams from the SLAC linac within a +- 0.8% momentum band, to have flexible tuning of the betatron and off-momentum functions for matching into the PEP storage ring, and to have convenient operating characteristics. The transport lines were brought into operation quickly and have operated well. Electron injection has been consistent and efficient and relatively easy to accomplish. Positron injection also has been satisfactory but is variable and more sensitive to ring conditions

Injection system for the PEP II asymmetric B Factory at SLAC

International Nuclear Information System (INIS)

Fieguth, T.; Bloom, E.; Bulos, F.; Davies-White, W.; Donald, M.; Fairfield, K.; Godfrey, G.; Holtzapple, R.; Ronan, M.; Zisman, M.

1992-01-01

The asymmetric energy B Factory proposed as an upgrade of PEP at Stanford Linear Accelerator Center will require a highly reliable and efficient injection system. The conceptual design has shown the feasibility of extracting 9 GeV electrons and 3.1 GeV positrons from the existing linac and injecting equal charges into 1658 buckets in each of the two rings of the collider. An injection study group has continued the development and study of this proposal and has generated workable designs for many related systems and subsystems. (author) 3 refs.; 4 figs.; 2 tabs

Collimation issues for the PEP-II B-factory

International Nuclear Information System (INIS)

Sullivan, M.

1997-12-01

This note describes how beam collimation affects detector backgrounds at the collision point for the PEP-II B-factory, a joint effort of three laboratories: LBNL, LLNL, and SLAC. Beam collimation controls the transverse size as well as the maximum allowed energy spread of the beam. The location of synchrotron radiation masks is determined by the transverse size of the beam in that the masks must prevent radiation generated by beam particles located at large transverse beam positions from directly striking the detector beam pipe. Collimation of the energy spread of the beam is important in the control of backgrounds produced by beam particles that strike a gas molecule (lost beam particles). The author describes some preliminary information from background studies during the first months of commissioning the high energy ring of the PEP-II B-factory and present some model predictions for synchrotron radiation backgrounds when collimators are not present

PEP-II IR-2 Alignment

International Nuclear Information System (INIS)

Seryi, A

2004-01-01

This paper describes the first results and preliminary analysis obtained with several alignment monitoring systems recently installed in the PEP-II interaction region. The hydrostatic level system, stretched wire system, and laser tracker have been installed in addition to the existing tiltmeters and LVDT sensors. These systems detected motion of the left raft, which correlated primarily with the low energy ring (LER) current. The motion is of the order of 120 micrometers. The cause was identified as synchrotron radiation heating the beampipe, causing its expansion which then results in its deformation and offset of the IR quadrupoles. We also discuss further plans on measurements, analysis and means to counteract this motion

Status of the PEP-II asymmetric B-Factory

International Nuclear Information System (INIS)

Mattison, T.S.

1994-11-01

The PEP-II project is an e + e - storage ring complex with unequal energy beams to study CP violation in the B meson system. High luminosity requires a large number of bunches and a low value of beta at the collision point. The high beam current requires advances in vacuum chambers, damped RF cavities, and feedback systems. Machine elements inside the detector are required to achieve low beta values and magnetic separation

An asymmetric B-meson factory at PEP

International Nuclear Information System (INIS)

Garren, A.; Chattopadhyay, S.; Chin, Y.; Oddone, P.; Zisman, M.S.; Donald, M.; Feldman, G.; Paterson, J.M.; Rees, J.

1989-03-01

A preliminary design for a B-factory has been made using asymmetric collisions between positrons in the PEP storage ring and electrons in a new, log-energy ring. The design utilizes small-aperture, permanent-magnet quadrupoles close to the interaction point (IP). Optimization of optical and beam parameters at the IP will be discussed, as well as the lattice design of the interaction region and of the rings. 7 refs., 3 figs., 2 tabs

Operator interface for the PEP-II low level RF control system

International Nuclear Information System (INIS)

Allison, S.; Claus, R.

1997-05-01

This paper focuses on the operational aspects of the low level RF control system being built for the PEP-II storage rings at SLAC. Subsystems requiring major operational considerations include displays for monitor and control from UNIX workstations, slow feedback loops and control sequences residing on microprocessors, and various client applications in the existing SLAC Linear Collider (SLC) control system. Since commissioning of PEP-II RF is currently in-progress, only those parts of the control system used during this phase are discussed in detail. Based on past experience with the SLC control system, it is expected that effort expended during commissioning on a solid user interface will result in smoother transition to full reliable 24-hour-a-day operation

Impedance of the PEP-II DIP screen

Energy Technology Data Exchange (ETDEWEB)

Ng, C -K [Stanford Linear Accelerator Center, Menlo Park, CA (United States); Weiland, T

1996-08-01

The vacuum chamber of a storage ring normally consists of periodically spaced pumping slots. The longitudinal impedance of slots are analyzed in this paper. It is found that although the broad-band impedance is tolerable, the narrow-band impedance, as a consequence of the periodicity of the slots, may exceed the stability limit given by natural damping with no feedback system on. Based on this analysis, the PEP-II distributed-ion-pump (DIP) screen uses long grooves with hidden holes cut halfway to reduce both the broad-band and narrow-band impedances. (author)

Impedance of the PEP-II DIP screen

International Nuclear Information System (INIS)

Ng, C.K.; Weiland, T.

1995-09-01

The vacuum chamber of a storage ring normally consists of periodically spaced pumping slots. The longitudinal impedance of slots are analyzed in this paper. It is found that although the broad-band impedance is tolerable, the narrow-band impedance, as a consequence of the periodicity of the slots, may exceed the stability limit given by natural damping with no feedback system on. Based on this analysis, the PEP-II distributed-ion-pump (DIP) screen uses long grooves with hidden holes cut halfway to reduce both the broad-band and narrow-band impedances

Positron--electron storage ring project: Stanford Linear Accelerator Center, Stanford, California. Final environmental statement

International Nuclear Information System (INIS)

1976-08-01

A final environmental statement is given which was prepared in compliance with the National Environmental Policy Act to support the Energy Research and Development Administration project to design and construct the positron-electron colliding beam storage ring (PEP) facilities at the Stanford Linear Accelerator Center (SLAC). The PEP storage ring will be constructed underground adjacent to the existing two-mile long SLAC particle accelerator to utilize its beam. The ring will be about 700 meters in diameter, buried at depths of 20 to 100 feet, and located at the eastern extremity of the SLAC site. Positron and electron beams will collide in the storage ring to provide higher energies and hence higher particle velocities than have been heretofore achieved. Some of the energy from the collisions is transformed back into matter and produces a variety of particles of immense interest to physicists. The environmental impacts during the estimated two and one-half years construction period will consist of movement of an estimated 320,000 cubic yards of earth and the creation of some rubble, refuse, and dust and noise which will be kept to a practical minimum through planned construction procedures. The terrain will be restored to very nearly its original conditions. Normal operation of the storage ring facility will not produce significant adverse environmental effects different from operation of the existing facilities and the addition of one water cooling tower. No overall increase in SLAC staff is anticipated for operation of the facility. Alternatives to the proposed project that were considered include: termination, postponement, other locations and construction of a conventional high energy accelerator

Ba anti Bar status report on the design of a detector for the study of CP violation at PEP-II at SLAC

International Nuclear Information System (INIS)

1993-06-01

Experiments designed to measure CP-violating asymmetries in the B meson system must emphasize exclusive state reconstruction with the highest possible resolution and efficiency. In the case of B 0 mesons produced in pairs at the Υ(4S) resonance at an asymmetric e + e - storage ring, this capability must be accompanied by precise vertex reconstruction in the direction of the e + e - beams (henceforth the z direction). These are difficult requirements, beyond the scope of any existing storage ring detector. The challenge of designing an asymmetric storage ring capable of producing the large number of neutral B meson pairs required to measure CP-violating asymmetries in decays to CP eigenstates has been handsomely met in the PEP-II design. As the first asymmetric e + e - storage ring, PEP-II presents a novel set of experimental challenges to a 4π detector. This Status Report describes the design of a new detector fully capable of exploiting the physics opportunities provided by PEP-II

Development of a high-power RF cavity for the PEP-II B factory

International Nuclear Information System (INIS)

Rimmer, R.A.; Allen, M.A.; Saba, J.; Schwarz, H.

1995-03-01

The authors describe the development and fabrication of the first high-power RF cavity for PEP-II. Design choices and fabrication technologies for the first cavity and subsequent production cavities are described. Conditioning and high-power testing of the first and subsequent cavities are discussed, as well as integration of the cavity into modular RF systems for both high-energy and low-energy rings. Plans for installation of the cavity raft assemblies in the RF sections of the PEP tunnel are also considered

Local chromatic correction scheme for LER of PEP-II

International Nuclear Information System (INIS)

Forest, E.; Robin, D.; Zholents, A.; Donald, M.; Helm, R.; Irwin, J.; Sullivan, M.K.

1993-01-01

The correction of the chromaticity of low-beta insertions in storage rings is usually made with sextupole lenses in the ring arcs. When decreasing the beta functions at the interaction point (IP), this technique becomes fairly ineffective, since it fails to properly correct the higher-order chromatic aberrations. Here we consider the approach for ampersand PEP-II B Factory low energy ring (LER) where the chromatic effects of the quadrupole lenses generating low beta functions at the IP are corrected locally with two families of sextupoles, one family for each plane. For the IP straight section the lattice is designed in such a way that the chromatic aberrations are made small and sextupole-like aberrations are eliminated. The results of dimensional tracking simulations are presented

Study of Beam-Beam Effects at PEP-II

International Nuclear Information System (INIS)

Narsky, I

2004-01-01

Using a self-consistent three-dimensional simulation running on parallel supercomputers, we have modeled the beam-beam interaction at the PEP-II asymmetric e + e - collider. To provide guidance for luminosity improvement, we scanned the tunes and currents in both rings and computed their impact on the luminosity and transverse beam sizes. We also studied the effects of colliding the beams with a small crossing angle. Where possible, the code was benchmarked against experimental measurements of luminosity and beam sizes, yielding an acceptable agreement

Configuring the SLC linac for injection into PEP

International Nuclear Information System (INIS)

Bane, K.L.F.

1989-01-01

From time to time the normal SLC physics program is to be interrupted so that beam can be delivered to PEP. In order that the switch to PEP injection (and the switch back again) can be accomplished quickly and easily, the gun, the damping rings, the linac phase ramp, the energy profile of the linac klystrons for the scavenger bunch, and the entire positron production system are to be kept the same as in the SLC configuration. What mainly remains to be changed is the linac klystron profile for the leading two bunches - those going to PEP. The new klystron profile must be such that it leaves these two beams (1) with final energies that match that of the storage ring and (2) with final energy spectra that fit within the energy aperture of the PEP transfer line. The conditions that need to be met in order to achieve these two goals are discussed in this note. 1 ref., 2 figs

An Orbit And Dispersion Correction Scheme for the PEP II

International Nuclear Information System (INIS)

Cai, Y.; Donald, M.; Shoaee, H.; White, G.; Yasukawa, L.A.

2011-01-01

To achieve optimum luminosity in a storage ring it is vital to control the residual vertical dispersion. In the original PEP storage ring, a scheme to control the residual dispersion function was implemented using the ring orbit as the controlling element. The 'best' orbit not necessarily giving the lowest vertical dispersion. A similar scheme has been implemented in both the on-line control code and in the simulation code LEGO. The method involves finding the response matrices (sensitivity of orbit/dispersion at each Beam-Position-Monitor (BPM) to each orbit corrector) and solving in a least squares sense for minimum orbit, dispersion function or both. The optimum solution is usually a subset of the full least squares solution. A scheme of simultaneously correcting the orbits and dispersion has been implemented in the simulation code and on-line control system for PEP-II. The scheme is based on the eigenvector decomposition method. An important ingredient of the scheme is to choose the optimum eigenvectors that minimize the orbit, dispersion and corrector strength. Simulations indicate this to be a very effective way to control the vertical residual dispersion.

Study of an instability of the PEP-II positron beam (Ohmi effect and Multipactoring)

Energy Technology Data Exchange (ETDEWEB)

Heifets, S A [Stanford Linear Accelerator Center, Menlo Park, CA (United States)

1996-08-01

The processes defining the density distribution of the photoelectrons are quite complicated. In this study, a simplified model of the instability was used to get a quick estimate of the growth rate of the instability and the relative importance of the parameters, as has been done in Ohmi`s paper. The production rate and dynamics of the photoelectrons are studied for the PEP-II parameters. The growth rate of the transverse instability driven by the primary photoelectrons is of the order of 0.7 msec for the PEP-II parameters. The multipactoring at resonance currents cannot produce large electron density due to the final energy spread caused by the finite bunch length and the intrinsic energy spread of the secondary electrons. Production of the secondary electrons may lead to large average densities. The ion can be produced in electron collisions with the residual gas with density of the order of the electron density. (G.K.)

RF Feedback Analysis for 4 cavities per klystron in PEP-II

International Nuclear Information System (INIS)

Corredoura, P.; Tighe, R.

1994-06-01

Lattice changes in the PEP-II high energy ring have made the concept of driving four cavities with a single klystron an attractive option. This paper examines the topology from a RF feedback point of view. Sources of error are identified and their magnitudes are estimated. The effect on the performance of the longitudinal impedance reducing feedback loops is calculated using control theory and Mathematica

Ba{anti B}ar status report on the design of a detector for the study of CP violation at PEP-II at SLAC

Energy Technology Data Exchange (ETDEWEB)

1993-06-01

Experiments designed to measure CP-violating asymmetries in the B meson system must emphasize exclusive state reconstruction with the highest possible resolution and efficiency. In the case of B{sup 0} mesons produced in pairs at the {Upsilon}(4S) resonance at an asymmetric e{sup +}e{sup {minus}} storage ring, this capability must be accompanied by precise vertex reconstruction in the direction of the e{sup +}e{sup {minus}} beams (henceforth the z direction). These are difficult requirements, beyond the scope of any existing storage ring detector. The challenge of designing an asymmetric storage ring capable of producing the large number of neutral B meson pairs required to measure CP-violating asymmetries in decays to CP eigenstates has been handsomely met in the PEP-II design. As the first asymmetric e{sup +}e{sup {minus}} storage ring, PEP-II presents a novel set of experimental challenges to a 4{pi} detector. This Status Report describes the design of a new detector fully capable of exploiting the physics opportunities provided by PEP-II.

The proposed injection system for an asymmetric B Factory in the PEP tunnel

International Nuclear Information System (INIS)

Bloom, E.; Bulos, F.; Loew, G.; Miller, R.; Sukiennicki, B.; Mattison, T.; Barletta, W.

1991-01-01

The proposed asymmetric energy B Factory to be built in the PEP tunnel at SLAC will require a highly effective and profuse source of low emittance electron and positron bunches. The B Factory will consist of two rings of equal size, a 9 GeV electron ring and a 3.1 GeV positron ring, each with 1658 bunches with total circulating currents of 1.5 and 2.1 amperes respectively. As the luminosity lifetime of the collider is expected to be about two hours, the injector should be capable of filling the rings in a small fraction of an hour. It turns out that with some simple modifications, the SLC linac with its damping rings and positron source is ideally suited to fulfill this function effectively. The overall injection system is described

A Low-Energy Ring Lattice Design

International Nuclear Information System (INIS)

Cai, Yunhai

2002-01-01

The PEP-N project at SLAC [1] consists of a Very Low-Energy small electron Ring (VLER) that will collide with the low-energy 3.1 GeV positron beam (LER) of PEP-II, producing center-of-mass energies between the 1.1 GeV and the J/ψ. The beams will collide head-on and will be separated in the detector magnetic field which is part of the Interaction Region [2]. The IP β functions were chosen such as to optimize both luminosity and beam-beam tune shifts, while keeping the LER tune shifts small. This paper describes the lattice design of the VLER for the ''baseline'' at 500 MeV

The electron-cloud instability in PEP-II: An update

International Nuclear Information System (INIS)

Furman, M.A.; Lambertson, G.R.

1997-05-01

The authors present an update on the estimate of the growth time of the multi-bunch transverse instability in the PEP-II collider arising from the interaction of the positron beam with the accumulated electron cloud. They estimate the contributions to the growth rate arising from the dipole magnets and from the pumping straight sections. They emphasize those quantities upon which the instability is most sensitive. The simulation includes measured data on the secondary emission yield for TiN-coated samples of the actual vacuum chamber. Although the analysis is still in progress, they conclude that the instability risetime is of order 1 ms, which is well within the range controllable by the feedback system

A search for supersymmetric electrons with the Mark II detector at PEP (Positron Electron Project)

Energy Technology Data Exchange (ETDEWEB)

LeClaire, B.W.

1987-10-01

An experimental search for selectrons, the supersymmetric partner of the electron, has been performed at the PEP storage ring at SLAC using the Mark II detector. The experimental search done was based upon hypothetical reaction in e/sup +/e/sup -/ interactions at PEP center of mass energies of 29 GeV. In this reaction the selectrons, e-tilde, are assumed produced by the interaction of one of initial state electrons with a photon radiated from the other initial state electron. This latter electron is assumed to continue down the beam pipe undetected. The photon and electron then produce a selectron and a photino, ..gamma..-tilde, in the supersymmetric analog of Compton scattering. The photino is assumed to be the lightest supersymmetric particle, and as such, does not interact in the detector, thereby escaping detection very much like a neutrino. The selectron is assumed to immediately decay into an electron and photino. This electron is produced with large p perpendicular with respect to the beam pipe, since it must balance the transverse momentum carried off by the photinos. Thus, the experimental signature of the process is a single electron in the detector with a large unbalanced tranverse momentum. No events of this type were observed in the original search of 123 pb/sup -1/ of data, resulting in a cross section limit of less than 2.4 x 10/sup -2/ pb (at the 95% CL) within the detector acceptance. This cross section upper limit applies to any process which produces anomalous single electron events with missing transverse momentum. When interpreted as a supersymmetry search it results in a lower selectron mass limit of 22.2 GeV/c/sup 2/ for the case of massless photinos. Limits for non-zero mass photinos have been calculated. 87 refs., 67 figs., 17 tabs.

A search for supersymmetric electrons with the Mark II detector at PEP [Positron Electron Project

International Nuclear Information System (INIS)

LeClaire, B.W.

1987-10-01

An experimental search for selectrons, the supersymmetric partner of the electron, has been performed at the PEP storage ring at SLAC using the Mark II detector. The experimental search done was based upon hypothetical reaction in e + e - interactions at PEP center of mass energies of 29 GeV. In this reaction the selectrons, e, are assumed produced by the interaction of one of initial state electrons with a photon radiated from the other initial state electron. This latter electron is assumed to continue down the beam pipe undetected. The photon and electron then produce a selectron and a photino, γ, in the supersymmetric analog of Compton scattering. The photino is assumed to be the lightest supersymmetric particle, and as such, does not interact in the detector, thereby escaping detection very much like a neutrino. The selectron is assumed to immediately decay into an electron and photino. This electron is produced with large p perpendicular with respect to the beam pipe, since it must balance the transverse momentum carried off by the photinos. Thus, the experimental signature of the process is a single electron in the detector with a large unbalanced tranverse momentum. No events of this type were observed in the original search of 123 pb -1 of data, resulting in a cross section limit of less than 2.4 x 10 -2 pb (at the 95% CL) within the detector acceptance. This cross section upper limit applies to any process which produces anomalous single electron events with missing transverse momentum. When interpreted as a supersymmetry search it results in a lower selectron mass limit of 22.2 GeV/c 2 for the case of massless photinos. Limits for non-zero mass photinos have been calculated. 87 refs., 67 figs., 17 tabs

Impedance analysis of the PEP-II vacuum chamber

International Nuclear Information System (INIS)

Ng, C.K.; Weiland, T.

1995-05-01

The PEP-II high energy ring (HER) vacuum chamber consists of a copper tube with periodically spaced pumping slots. The impedance of the vacuum chamber due to the slots is analyzed. Both narrow-band and broadband impedances are considered as well as longitudinal and transverse components thereof. It is found that although the broad-band impedance is tolerable, the narrow-band impedance may exceed the instability limit given by the natural damping with no feedback system on. Traveling wave modes in the chamber are the major source of this high value narrow-band impedance. We also study the dependences of the impedance on the slot length and the geometrical cross section

Detector solenoid compensation in the PEP-II B-Factory

International Nuclear Information System (INIS)

Nosochkov, Y.; Cai, Y.; Irwin, J.; Sullivan, M.

1995-01-01

The PEP-II experimental detector includes a strong 1.5 T solenoid field in the interaction region (IR). With the fringe fields, the solenoid extends over a range of 6 m. Additional complications are that (1) it is displaced longitudinally from the interaction point (IP) by about 40 cm, (2) neither beam is parallel to the solenoid axis, and (3) the solenoid overlaps a dipole and a quadrupole on either side of the IP. In each half IR the correction system includes a set of skew quadrupoles, dipole correctors and normal quadrupoles to independently compensate the coupling, orbit perturbation, dispersion and focusing effect produced by the solenoid. The correction schemes for the Low Energy Ring (LER) and for the High Energy Ring (HER) are described, and the impact on the dynamic aperture is evaluated

BEPC II positron source

International Nuclear Information System (INIS)

Pei Guoxi; Sun Yaolin; Liu Jintong; Chi Yunlong; Liu Yucheng; Liu Nianzong

2006-01-01

BEPC II-an upgrade project of the Beijing Electron Positron Collider (BEPC) is a factory type of e + e - collider. The fundamental requirements for its injector linac are the beam energy of 1.89 GeV for on-energy injection and a 40 mA positron beam current at the linac end with a low beam emittance of 1.6 μm and a low energy spread of ±0.5% so as to guarantee a higher injection rate (≥50 mA/min) to the storage ring. Since the positron flux is proportional to the primary electron beam power on the target, the authors will increase the electron gun current from 4A to 10A by using a new electron gun system and increase the primary electron energy from 120 MeV to 240 MeV. The positron source itself is an extremely important system for producing more positrons, including a positron converter target chamber, a 12kA flux modulator, the 7m focusing module with DC power supplies and the support. The new positron production linac from the electron gun to the positron source has been installed into the tunnel. In what follows, the authors will emphasize the positron source design, manufacture and tests. (authors)

PEP-II asymmetric B Factory: Design update and R ampersand D results

International Nuclear Information System (INIS)

Zisman, M.S.; Bell, R.A.; Dorfan, J.; Schwarz, H.; Barletta, W.A.; Calderon, M.

1992-07-01

PEP-II, a 9 GeV x 3.1 GeV e + e - collider with a design luminosity of 3 x 10 33 cm -2 s -1 , was proposed jointly by SLAC, LBL, and LLNL. Recent efforts have continued towards an optimized design. In addition, an aggressive R ampersand D program is under way to validate our design choices. Fabrication of a low-power prototype RF cavity is complete, and impedance measurements are beginning. A 500-kW, 476-MHz klystron has been completed; it will be used for testing both high-power RF windows and a prototype high-power cavity (now under design in collaboration with Chalk River Laboratory). Vacuum studies have demonstrated that chambers with suitable photodesorption properties can be fabricated. A mockup of the two-ring arc area has been completed and used to investigate alignment and stability issues. The PEP-II project is ready to begin construction as soon as funds become available

Diagnosing the PEP-II Injection System

Energy Technology Data Exchange (ETDEWEB)

Decker, F.-J.; Donald, M.H.; Iverson, R.H.; Kulikov, A.; Pappas, G.C.; Weaver, M.; /SLAC

2005-05-09

The injection of beam into the PEP-II B-Factory, especially into the High Energy Ring (HER) has some challenges. A high background level in the BaBar detector has for a while inhibited us from trickling charge into the HER similar to the Low Energy Ring (LER). Analyzing the injection system has revealed many issues which could be improved. The injection bump between two kickers was not closed, mainly because the phase advance wasn't exactly 180{sup o} and the two kicker strengths were not balanced. Additionally we found reflections which kick the stored beam after the main kick and cause the average luminosity to drop about 3% for a 10 Hz injection rate. The strength of the overall kick is nearly twice as high as the design, indicating a much bigger effective septum thickness. Compared with single beam the background is worse when the HER beam is colliding with the LER beam. This hints that the beam-beam force and the observed vertical blow-up in the HER pushes the beam and especially the injected beam further out to the edge of the dynamic aperture or beyond.

Diagnosing the PEP-II Injection System

International Nuclear Information System (INIS)

Decker, F.-J.; Donald, M.H.; Iverson, R.H.; Kulikov, A.; Pappas, G.C.; Weaver, M.; SLAC

2005-01-01

The injection of beam into the PEP-II B-Factory, especially into the High Energy Ring (HER) has some challenges. A high background level in the BaBar detector has for a while inhibited us from trickling charge into the HER similar to the Low Energy Ring (LER). Analyzing the injection system has revealed many issues which could be improved. The injection bump between two kickers was not closed, mainly because the phase advance wasn't exactly 180 o and the two kicker strengths were not balanced. Additionally we found reflections which kick the stored beam after the main kick and cause the average luminosity to drop about 3% for a 10 Hz injection rate. The strength of the overall kick is nearly twice as high as the design, indicating a much bigger effective septum thickness. Compared with single beam the background is worse when the HER beam is colliding with the LER beam. This hints that the beam-beam force and the observed vertical blow-up in the HER pushes the beam and especially the injected beam further out to the edge of the dynamic aperture or beyond

HOM power propagation and attenuation in PEP-II B-factory

International Nuclear Information System (INIS)

Lin, X.E.; Ng, C.K.; Ko, K.

1997-09-01

Most of the higher-order-mode (HOM) power that propagates in the PEP-II rings is generated i the RF cavities but its content in terms of TE and TM components has not been accurately determined. For purpose of shielding beamline components such as bellows and BPMs from TE power penetration and determining the heating on the cavity HOM absorber, this HOM power content and its distribution profile around the rings are needed. This paper calculates the TE and TM contributions of the RF cavities to the circulating HOM power and their transmission properties at another cavity downstream. By considering both the generation in, and scattering by the cavities, as well as the attenuation along the vacuum chamber, a complete distribution profile for the TE and TM HOM power can be obtained

Bunch-by-bunch longitudinal feedback system for PEP-II

International Nuclear Information System (INIS)

Oxoby, G.; Claus, R.; Fox, J.

1994-06-01

This paper describes the implementation of the bunch-by-bunch longitudinal feedback system for the PEP-II B Factory. Bunch spacing down to 2 ns is achieved using 500 Megasamples per second A/D and D/A converters, and AT ampersand T 1610 Digital Signal Processors are integrated to run a downsampled feedback algorithm for each bunch in parallel. This general purpose programmable system, packaged in VXI and VME, is modular and scalable to offer portability to other accelerator rings. The control and monitoring hardware and software architecture have been developed to provide ease of operation as well as diagnostic tools for machine physics

1997 Annual Site Environmental Report (ASER)

International Nuclear Information System (INIS)

Holden, Gene

1998-01-01

The SLAC program centers around experimental and theoretical research in elementary particle physics using accelerated electron beams and a broad program of research in atoms and solid-state physics, chemistry, and biology using synchrotron radiation from accelerated electron beams. There is also an active program in the development of accelerators, detectors, and new sources and instrumentation for synchrotron radiation research. The main instrument of research is the 3.2-km linear accelerator (linac) that generates high intensity beams of electrons and positrons up to 50 GeV, which are among the highest energy electron and positron beams available in the world. The linac is also used for injecting electrons and positrons into colliding-beam storage rings for particle physics research. The Positron-Electron Project (PEP) storage ring is about 800 meters in diameter. The PEP program was completed several years ago. PEP is now being upgraded to serve as an Asymmetric B Factory (or PEP-II) that will study the B meson. PEP-II will make use of much of PEP's existing equipment and infrastructure, and is scheduled for completion in 1998. A smaller storage ring, the Stanford Positron-Electron Asymmetric Ring (SPEAR) has its own smaller linac and a booster ring for injecting accelerated beams of electrons. SPEAR is fully dedicated to synchrotron radiation research. The synchrotron light generated by the SPEAR storage ring is used by the Stanford Synchrotron Radiation Laboratory (SSRL) to perform experiments. Scientists from all parts of the United States and from throughout the world participate in the experimental programs at SLAC

1997 Annual Site Environmental Report (ASER)

Energy Technology Data Exchange (ETDEWEB)

Holden, Gene

1998-10-01

The SLAC program centers around experimental and theoretical research in elementary particle physics using accelerated electron beams and a broad program of research in atoms and solid-state physics, chemistry, and biology using synchrotron radiation from accelerated electron beams. There is also an active program in the development of accelerators, detectors, and new sources and instrumentation for synchrotron radiation research. The main instrument of research is the 3.2-km linear accelerator (linac) that generates high intensity beams of electrons and positrons up to 50 GeV, which are among the highest energy electron and positron beams available in the world. The linac is also used for injecting electrons and positrons into colliding-beam storage rings for particle physics research. The Positron-Electron Project (PEP) storage ring is about 800 meters in diameter. The PEP program was completed several years ago. PEP is now being upgraded to serve as an Asymmetric B Factory (or PEP-II) that will study the B meson. PEP-II will make use of much of PEP's existing equipment and infrastructure, and is scheduled for completion in 1998. A smaller storage ring, the Stanford Positron-Electron Asymmetric Ring (SPEAR) has its own smaller linac and a booster ring for injecting accelerated beams of electrons. SPEAR is fully dedicated to synchrotron radiation research. The synchrotron light generated by the SPEAR storage ring is used by the Stanford Synchrotron Radiation Laboratory (SSRL) to perform experiments. Scientists from all parts of the United States and from throughout the world participate in the experimental programs at SLAC.

Status Report and Future Plans for the PEP-II B Factory

International Nuclear Information System (INIS)

Fisher, Alan S.

2001-01-01

The PEP-II B Factory at SLAC has been in operation with the BABAR detector since the summer of 1999. The peak currents and luminosity steadily increased through the end of the 2000 run on October 31. By that time, 0.75 A of electrons (the design current) routinely collided with 1.4 A of positrons in 657 bunches, to give a peak luminosity of 2.6 x 10 33 cm -2 s -1 . We delivered an integrated luminosity of up to 184 pb -1 per day and 1033 per week; BABAR logged a total of 25 fb -1 . Three days of machine development at the end of the run raised the peak luminosity to 3.29 x 10 33 , exceeding the design goal of 3.0. BABAR then logged data for an hour, starting with a peak of 3.20. Next, we achieved the design value for positron current, 2.14 A, operating without collisions. The major limitation has been growth in the size of the positron beam in the low-energy ring (LER) due to electron clouds and multipacting. Since the arcs benefit from antechambers and a TiN coating with low secondary emission, our efforts have concentrated on the straights, where we added solenoid windings. Each straight wound allowed higher LER current without blow-up, and a consequent increase in luminosity. Measurements of the bunch-by-bunch luminosity showed that the effect becomes significant by about the tenth bunch in a train, but clears after a short gap. Careful control of the fill pattern has thus been essential in raising luminosity. For the 2001 run, which began in February, we added a third LER RF station, to collide with more LER current and more bunches, and also tried reducing β* x from 50 to 35 cm, with the goal of reaching a luminosity of 5 x 10 33 by year's end. In 2003, we plan to add a fourth LER and sixth HER RF station to reach 1 x 10 34

Simulation of PEP-II Accelerator Backgrounds Using TURTLE

CERN Document Server

Barlow, Roger J; Kozanecki, Witold; Majewski, Stephanie; Roudeau, Patrick; Stocchi, Achille

2005-01-01

We present studies of accelerator-induced backgrounds in the BaBar detector at the SLAC B-Factory, carried out using a modified version ofthe DECAY TURTLE simulation package. Lost-particle backgrounds in PEP-II are dominated by a combination of beam-gas bremstrahlung, beam-gas Coulomb scattering, radiative-Bhabha events and beam-beam blow-up. The radiation damage and detector occupancy caused by the associated electromagnetic shower debris can limit the usable luminosity. In order to understand and mitigate such backgrounds, we have performed a full programme of beam-gas and luminosity-background simulations, that include the effects of the detector solenoidal field, detailed modelling of limiting apertures in both collider rings, and optimization of the betatron collimation scheme in the presence of large transverse tails.

The positron accumulator ring for the APS

International Nuclear Information System (INIS)

Crosbie, E.A.

1989-01-01

The Positron Accumulator Ring (PAR) is designed to accumulate and damp positrons from the 450-MeV linac during the 0.5-s cycle time of the injector synchrotron for the APS 7-GeV storage ring. During 0.4 s of each synchrotron cycle, up to 24 linac pulses are injected into the horizontal phase space of the PAR at a 60-Hz rate. Each injected pulse occupies about 1.3 of the circumference of the accumulator ring. After 0.1 s for longitudinal damping, the single accumulated bunch is transferred to one of the 353-MHz buckets of the injector synchrotron RF system. The bunch is accelerated to 7 GeV and transferred to the storage ring, while the PAR accumulates the next bunch of positrons. 2 refs., 3 figs., 2 tabs

The positron accumulator ring for the APS

International Nuclear Information System (INIS)

Crosbie, E.A.

1989-01-01

The Positron Accumulator Ring (PAR) is designed to accumulate and damp positrons from the 450-MeV linac during the 0.5-s cycle time of the injector synchrotron for the APS 7-GeV storage ring. During 0.4 s of each synchrotron cycle, up to 24 linac pulses are injected into the horizontal phase space of the PAR at a 60-Hz rate. Each injected pulse occupies about 1/3 of the circumference of the accumulator ring. After 0.1 s for longitudinal damping, the single accumulated bunch is transferred to one of the 353-MHz buckets of the injector synchrotron RF system. The bunch is accelerated to 7 GeV and transferred to the storage ring, while the PAR accumulates the next bunch of positrons. 2 refs., 3 figs., 2 tabs

The PEP-II Lower Pressure HER Vacuum Chamber

International Nuclear Information System (INIS)

DeBarger, S.; Metcalfe, S.; Seeman, J.; Sullivan, M.; Wienands, U.; Wright, D.

2006-01-01

This new vacuum chamber has been installed from 12 to 21 meters upstream of the BaBar detector in the PEP-II High Energy Ring (HER) to reduce lost particle backgrounds. The backgrounds from HER now dominate the backgrounds in the BaBar detector and the present vacuum pressure is 1 x 10 -9 Torr. The new chamber will increase the pumping significantly by adding 18 x 2000 l/s titanium sublimation pumps to the existing 5 x 440 l/s ion pumps, and is expected to reduce the pressure by about a factor of five. Features of the chamber include improved water cooling, improved vacuum conductance through copper RF screens featuring over 15,000 small square holes and the ability to sublimate titanium while the beam is still on

The PEP-II project-wide database

International Nuclear Information System (INIS)

Chan, A.; Calish, S.; Crane, G.; MacGregor, I.; Meyer, S.; Wong, J.

1995-05-01

The PEP-II Project Database is a tool for monitoring the technical and documentation aspects of this accelerator construction. It holds the PEP-II design specifications, fabrication and installation data in one integrated system. Key pieces of the database include the machine parameter list, magnet and vacuum fabrication data. CAD drawings, publications and documentation, survey and alignment data and property control. The database can be extended to contain information required for the operations phase of the accelerator and detector. Features such as viewing CAD drawing graphics from the database will be implemented in the future. This central Oracle database on a UNIX server is built using ORACLE Case tools. Users at the three collaborating laboratories (SLAC, LBL, LLNL) can access the data remotely, using various desktop computer platforms and graphical interfaces

Evaluation of the BEAM--BEAM effect in PEP using Myer's simulation program

International Nuclear Information System (INIS)

Hutton, A.

1982-09-01

The program BEAM BEAM written by Steve Myers for the LEP machine at CERN has given encouraging results in the simulation of the beam-beam effect in electron-positron storage rings. It therefore seemed worthwhile to apply the program to PEP with two main intentions. Firstly, to confirm the validity of the program by comparison with experimental data from previous PEP runs and secondly, to search for an improvement in the operating conditions of PEP. Clearly a successful prediction would also enhance the credibility of the program. The program itself has been extensively described in the literature and will not be repeated here, except for some comments of direct relevance to the present simulation. 14 refs., 15 figs., 4 tabs

PEP storage ring: current status

International Nuclear Information System (INIS)

Rees, J.R.

1981-02-01

This report comments on the performance of the subsystems of PEP, discusses the beam dynamical behavior of the machine and compares it with our expectations and, finally, describes plans for improving PEP

PEGASYS---A proposed internal target facility for the PEP storage ring

International Nuclear Information System (INIS)

Van Biber, K.

1988-07-01

A proposal for an integral gas-jet target and forward spectrometer for the PEP storage ring is described. The beam structure, allowable, luminosity (L = 10 33 cm/sup /minus/2/s/sup /minus/1/ for H 2 , D 2 ) and energy (E/sub e/ ≤ 15 GeV) make the ring ideal for multiparticle coincidence studies in the scaling regime, and where perturbative QCD may be an apt description of some exclusive and semi-inclusive reactions. 14 refs., 7 figs

Trickle-Charge: a New Operational Mode for PEP-II

International Nuclear Information System (INIS)

Kozanecki, W.; Colocho, W.S.; Decker, F.-J.; Ecklund, S.; Fisher, A.S.; Iverson, R.H.; O'Grady, C.; Seeman, J.; Sullivan, M.K.; Turner, J.L.; Weaver, M.; Wienands, U.; SLAC

2005-01-01

In regular top-up-and-coast operation, PEP-II average luminosity is about 70-75% of the peak luminosity due to detector ramp-down and ramp-up times plus the time it takes to top-up both beams. We recently commissioned a new operational mode where the Low Energy Ring is injected continuously without ramping down the detector. The benefits--increased luminosity lifetime and roughly half the number of top-ups per shift--were expected to give an increase in delivered luminosity of about 15% at the same peak luminosity; this was confirmed in test runs. In routine trickle operation, however, it appears that the increase in delivered luminosity is more than twice that due to an increase in availability credited to the more stable operating conditions during trickle operation. Further gains were made when continuous injection was extended to the high energy ring as well. In this paper we will present our operational experience as well as some of the diagnostics we use to monitor and maintain tuning of the machine in order to control injection background and protect the detector

PEP-II design update and R ampersand D results

International Nuclear Information System (INIS)

Zisman, M.S.

1993-01-01

We describe the present status of the PEP-II asymmetric β factory design undertaken by SLAC, LBL, and LLNL. Design optimization during the past year and changes from the original CDR design are described. R ampersand D activities have focused primarily on the key technology areas of vacuum, RF, and feedback system design. Recent progress in these areas is described. The R ampersand D results have verified our design assumptions and provide further confidence in the design of PEP-II

Streak-Camera Measurements with High Currents in PEP-II and Variable Optics in SPEAR3

Energy Technology Data Exchange (ETDEWEB)

Cheng, Weixeng; Fisher, Alan, a Corbett, Jeff; /SLAC

2008-06-05

A dual-axis, synchroscan streak camera was used to measure longitudinal bunch profiles in three storage rings at SLAC: the PEP-II low- and high-energy rings, and SPEAR3. At high currents, both PEP rings exhibit a transient synchronous-phase shift along the bunch train due to RF-cavity beam loading. Bunch length and profile asymmetry were measured along the train for a range of beam currents. To avoid the noise inherent in a dual-axis sweep, we accumulated single-axis synchroscan images while applying a 50-ns gate to the microchannel plate. To improve the extinction ratio, an upstream mirror pivoting at 1 kHz was synchronized with the 2kHz MCP gate to deflect light from other bunches off the photocathode. Bunch length was also measured on the HER as a function of beam energy. For SPEAR3 we measured bunch length as a function of single-bunch current for several lattices: achromatic, low-emittance and low momentum compaction. In the first two cases, resistive and reactive impedance components can be extracted from the longitudinal bunch profiles. In the low-alpha configurations, we observed natural bunch lengths approaching the camera resolution, requiring special care to remove instrumental effects, and saw evidence of periodic bursting.

The PEP injection system

International Nuclear Information System (INIS)

Brown, K.L.; Avery, R.T.; Peterson, J.M.

1988-01-01

A system to transport 10-to-15-GeV electron and positron beams from the Stanford Linear Accelerator and to inject them into the PEP storage ring under a wide variety of lattice configurations has been designed. Optically, the transport line consists of three 360/degree/ phase-shift sections of FODO lattice, with bending magnets interspersed in such a way as to provide achromaticity, convenience in energy and emittance definition, and independent tuning of the various optical parameters for matching into the ring. The last 360/degree/ of phase shift has 88 milliradians of bend in a vertical plane and deposits the beam at the injection septum via a Lambertson magnet. Injection is accomplished by launching the beam with several centimeters of radial betatron amplitude in a fast bump provided by a triad of pulsed kicker magnets. Radiation damping reduces the collective amplitude quickly enough to allow injection at a high repetition rate

The First Year of the BABAR Experiment at PEP-II

Energy Technology Data Exchange (ETDEWEB)

Barrera, Barbara

2000-12-18

The BABAR detector, situated at the SLAC PEP-II asymmetric e{sup +}e{sup -} collider, has been recording data at energies on and around the {Upsilon}(4S) resonance since May 1999. In this paper, we briefly describe the PEP-II B Factory and the BABAR detector. The performance presently achieved by the experiment in the areas of tracking, vertexing, calorimetry and particle identification is reviewed. Analysis concepts that are used in the various papers submitted to this conference are also discussed.

Design of the PEP-II Interaction Region Septum Quadrupole

Science.gov (United States)

Osborn, J.; Tanabe, J.; Yee, D.; Younger, F.

1997-05-01

The PEP-II QF2 magnet is one of the final focus quadrupoles for the Low-Energy Ring (LER) and utilizes a septum aperture to accommodate the adjacent High-Energy Ring (HER) beamline. The LER lattice design specification calls for an extremely high field quality for this magnet. A conventional water-cooled copper coil and laminated steel core design was selected to allow adjustment in the excitation. The close proximity between the LER and HER beamlines and the required integrated quadrupole strength result in a moderately high current density septum design. The QF2 magnets are imbedded in a confined region at each end of the BaBar detector, thus requiring a small magnet core cross section. Pole face windings are included in the QF2 design to buck the skew octupole term induced by the solenoidal fringe field that leaks out of the detector. Back-leg windings are included to buck a small dipole component induced by the lack of perfect quadrupole symmetry in this septum design. 2D pole contour optimization and 3D end chamfers are used to minimize harmonic errors; a separate permanent-magnet Harmonic Corrector Ring compensates for remaining field errors. The design methods and approach, 2D and 3D analyses, and the resulting expected magnet performance are described in this paper.

PEP-II Large Power Supplies Rebuild Program at SLAC

CERN Document Server

de Lira, Antonio C; Lipari, James J; da Silva Rafael, Fernando

2005-01-01

At PEP-II, seven large power supplies (LGPS) are used to power quad magnets in the electron-positron collider region. The LGPS ratings range from 72kW to 270kW, and were installed in 1997. They are unipolar off-line switch mode supplies, with a 6 pulse bridge rectifying 480VAC, 3-phase input power to yield 650VDC unregulated. This unregulated 650VDC is then input into one (or two) IGBT H-bridges, which convert the DC into PWM 16 kHz square wave AC. This high frequency AC drives the primary side of a step-down transformer followed by rectifiers and low pass filters. Over the years, these LGPS have presented many problems mainly in their control circuits, making it difficult to troubleshoot and affecting the overall accelerator availability. A redesign/rebuilding program for these power supplies was established under the coordination of the Power Conversion Department at SLAC. During the 2004 accelerator summer shutdown all the control circuits in these supplies were redesigned and replaced. A new PWM control b...

PEP-X: An Ultimate Storage Ring Based on Fourth-Order Geometric Achromats

Energy Technology Data Exchange (ETDEWEB)

Cai, Yunhai; Bane, Karl; Hettel, Robert; Nosochkov, Yuri; Wang, Min-Huey; /SLAC

2012-04-06

We have designed an 'ultimate' storage ring for the PEP-X light source that achieves the diffraction limited emittances (at 1.5 {angstrom}) of 12 pm-rad in both horizontal and vertical planes with a 4.5-GeV beam. These emittances include the contribution of intrabeam scattering at a nominal current of 200 mA in 3300 bunches. This quality beam in conjunction with a conventional 4-m undulator in a straight section can generate synchrotron radiation having a spectral brightness above 10{sup 22} [photons/s/mm{sup 2}/mrad{sup 2}/0.1% BW] at a 10 keV photon energy. The high coherence at the diffraction limit makes PEP-X competitive with 4th generation light sources based on an energy recovery linac. In addition, the beam lifetime is several hours and the dynamic aperture is large enough to allow off-axis injection. The alignment and stability tolerances, though challenging, are achievable. A ring with all these properties is only possible because of several major advances in mitigating the effects of nonlinear resonances.

Study of an instability of the PEP-II positron beam (Ohmi effect and multipactoring)

International Nuclear Information System (INIS)

Heifets, S.A.

1995-11-01

The paper is organized in the following way. First, Ohmi effect induced by direct flow of primary photoelectrons is studied for the PEP-II parameters. The production rate and kinematics take into account the antechamber of the LER. We discuss the effect of the secondary emission of electrons in the AL chamber, where the yield is larger than one. Resonance multipactoring is considered, and then the average density of the secondary electrons is estimated taking into account the space-charge effect and the interaction with the beam. We show that in the extreme case there is a self-consistent regime similar to the regime of the space-charge dominated cathode. Finally, the rate of ion production by accumulated electrons and the possibility of the ion induced pressure instability is discussed

Identifying Lattice, Orbit, And BPM Errors in PEP-II

International Nuclear Information System (INIS)

Decker, F.-J.; SLAC

2005-01-01

The PEP-II B-Factory is delivering peak luminosities of up to 9.2 · 10 33 1/cm 2 · l/s. This is very impressive especially considering our poor understanding of the lattice, absolute orbit and beam position monitor system (BPM). A few simple MATLAB programs were written to get lattice information, like betatron functions in a coupled machine (four all together) and the two dispersions, from the current machine and compare it the design. Big orbit deviations in the Low Energy Ring (LER) could be explained not by bad BPMs (only 3), but by many strong correctors (one corrector to fix four BPMs on average). Additionally these programs helped to uncover a sign error in the third order correction of the BPM system. Further analysis of the current information of the BPMs (sum of all buttons) indicates that there might be still more problematic BPMs

Background estimates for PEP

International Nuclear Information System (INIS)

Martin, F.

1975-04-01

The beam gas bremsstrahlung radiation for PEP has been studied in detail using the ray trace program TURTLE. With this program, an electron (positron) trajectory starting at an interaction region is traced through the storage ring until it radiates, then the radiated electron is traced until it stops in the beam pipe. The relative number of electrons stopping between the strong focusing quadrupoles is used to determine a rate at which electromagnetic showers will occur in the region of the experimental apparatus. It was found that 2.46% of the radiated electrons will stop in the interaction region. Assuming a uniform pressure of 2 x 10/sup /minus/9/ Torr in the vacuum pipe for a residual gas (X/sub o/ = 34.7 gm/cm 2 ), 2.5 x 10 5 electrons (positrons) will stop in the interaction region per beam (4 x 10 12 electrons at 15 GeV) per second. If the luminosity is 10 32 , this rate is equivalent to a cross section of 2.5 x 10/sup /minus/27/ cm 2 . 4 figs., 3 tabs

A unique power supply for the PEP II klystron at SLAC

International Nuclear Information System (INIS)

Cassel, R.; Nguyen, M.N.

1997-07-01

Each of the eight 1.2 MW RF klystrons for the PEP-II storage rings require a 2.5 MVA DC power supply of 83 Kv at 23 amps. The design for the supply was base on three factors, low cost, small size to fit existing substation pads, and good protection against damage to the klystron including klystron gun arcs. The supply uses a 12 pulse 12.5 KV primary thyristor star point controller with primary filter inductor to provide rapid voltage control, good voltage regulation, and fast turn off during klystron tube faults. The supply also uses a unique secondary rectifier, filter capacitor configuration to minimize the energy available under a klystron fault. The voltage control is from 0--90 KV with a regulation of < 0.1% and voltage ripple of < 1% P-P, (< 0.2% RMS) above 60 KV. The supply utilizes a thyristor crowbar, which under a klystron tube arc limits the energy in the klystron arc to < 5 joules. If the thyristor crowbar is disabled the energy supplied is < 40 joules into the arc. The size of the supply was reduced small enough to fit the existing PEP transformer yard pads. The cost of the power supply was < $140 per KVA

PEP conceptual design report

International Nuclear Information System (INIS)

1976-02-01

The accelerator system design, the physical plant, the experimental areas, cost estimates, and schedules for PEP are discussed. The main component of the proposed facility is a storage ring in which beams of positrons and electrons circulate in opposite directions in a vacuum chamber embedded in a magnetic guide field having six bending arcs and six long straight sections. The electrons and positrons to be stored in it are produced in the SLAC linac and are introduced into the storage ring via two beam transport paths emanating from the end of the two-mile accelerator. Beams of energies up to 18 GeV can be stored, and, at a future date, components could be added to permit energies as high as 22 GeV. Provisions are also made in the design of the ring housing so that a synchrotron-radiation research facility could be added in the future. The energy lost from the beams by synchrotron radiation is restored by a high-power radio frequency accelerating system which employs klystrons to drive the accelerating structures at a frequency of 353 MHz. The system is capable of delivering five megawatts of power to the beams. Low pressures will be sustained by means of long, narrow sputter-ion pumps located in the vacuum chamber in the bending magnets directly alongside the beams. The proposed storage ring is designed to generate a luminosity (reaction rate per unit reaction cross section) of more than 10 31 cm -2 sec -1 per interaction region at beam energies between 5 GeV and 18 GeV and a maximum luminosity of 10 32 cm -2 sec -1 per interaction region at a beam energy of 15 GeV

Measurement of the leptonic structure functions of the photon at PEP [Positron Electron Project

International Nuclear Information System (INIS)

Cain, M.P.

1987-01-01

At beam energies available at the PEP e + e - storage ring at the Stanford Linear Accelerator Center the cross-section for two-photon particle production is sufficiently large to warrant an investigation of this O(α 4 ) process. Of particular interest is the two-photon process ee → eeμμ at non-zero Q 2 . This channel is not only relatively easy to observe experimentally but also serves as a model for the process ee → eeq bar q. For the case of inelastic eγ scattering the cross-section could be parameterized in terms of the photon structure functions F 1 (x,Q 2 ) and F 2 (x,Q 2 ). In this thesis I will present data on the process ee → eeμμ collected by the Two-Photon collaboration (PEP-9) at PEP. For the subset of data which proceeds by inelastic eγ scattering I will present a procedure for extracting the QED photon structure functions and apply this method to the data. 42 refs., 44 figs

Background sources at PEP

International Nuclear Information System (INIS)

Lynch, H.; Schwitters, R.F.; Toner, W.T.

1988-01-01

Important sources of background for PEP experiments are studied. Background particles originate from high-energy electrons and positrons which have been lost from stable orbits, γ-rays emitted by the primary beams through bremsstrahlung in the residual gas, and synchrotron radiation x-rays. The effect of these processes on the beam lifetime are calculated and estimates of background rates at the interaction region are given. Recommendations for the PEP design, aimed at minimizing background are presented. 7 figs., 4 tabs

PEP sextupoles

International Nuclear Information System (INIS)

Brunk, W.O.

1976-10-01

The sextupole requirements of PEP are such that they represent a much larger proportion of the ring magnet cost than they did in SPEAR. A study is given of various fabrication techniques all pointed toward cost reduction without an undue sacrifice of function quality. The point of debarkation is the sextupole design as described in the PEP Conceptual Design Report. There are three main areas of inquiry, namely, pole tip contour, coil material and fabrication and yoke size

Optimizing the injection straight of PEP II asymmetric B Factory at SLAC

International Nuclear Information System (INIS)

Bulos, F.; Bloom, E.; Davies-White, W.; Donald, M.; Fairfield, K.; Fieguth, T.; Godfrey, G.; Holtzapple, R.; Hutton, A.; Loew, G.; Miller, R.; Sukiennicki, B.; Wen, H.; Ronan, M.

1992-04-01

The asymmetric energy PEP II B Factory proposed as an upgrade of PEP at the Stanford Linear Accelerator Center requires both a powerful low emittance source of e - e + and a very reliable and efficient injection system. The SLC linac fulfills the source requirement very well. We describe here the optimization of the optics of the injection straight to insure reliable and efficient injection

Optimizing the injection straight of PEP II asymmetric B factory at SLAC

International Nuclear Information System (INIS)

Bulos, F.; Bloom, E.; Davies-White, W.; Donald, M.; Fairfield, K.; Fieguth, T.; Godfrey, G.; Holtzapple, R.; Hutton, A.; Loew, G.; Miller, R.; Sukiennicki, B.; Wen, H.

1992-01-01

The asymmetric energy PEP II B Factory proposed as an upgrade of PEP at the Stanford Linear Accelerator Center requires both a powerful low emittance source of e - e + and a very reliable and efficient injection system. The SLC linac fulfills the source requirement very well. We describe here the optimization of the optics of the injection straight to insure reliable and efficient injection

RF feedback simulation results for PEP-II

International Nuclear Information System (INIS)

Tighe, R.; Corredoura, P.

1995-06-01

A model of the RF feedback system for PEP-II has been developed to provide time-domain simulation and frequency-domain analysis of the complete system. The model includes the longitudinal beam dynamics, cavity fundamental resonance, feedback loops, and the nonlinear klystron operating near saturation. Transients from an ion clearing gap and a reference phase modulation from the longitudinal feedback system are also studied. Growth rates are predicted and overall system stability examined

Improvement of PEP-II Linear Optics with a MIA-Derived Virtual Accelerator

International Nuclear Information System (INIS)

Cerio, B.; Colgate U.

2006-01-01

In several past studies, model independent analysis, in conjunction with a virtual accelerator model, has been successful in improving PEP-II linear geometric optics. In many cases, optics improvement yielded an increase in machine luminosity. In this study, an updated characterization of linear optics is presented. With the PEP-II beam position monitor (BPM) system, four independent beam centroid orbits were extracted and used to determine phase advances and linear Green's functions among BPM locations. A magnetic lattice model was then constructed with a singular value decomposition-enhanced least-square fitting of phase advances and Green's functions, which are functions of quadrupole strengths, sextupole feed-downs, as well as BPM errors, to the corresponding measured quantities. The fitting process yielded a machine model that matched the measured linear optics of the real machine and was therefore deemed the virtual accelerator. High beta beat, as well as linear coupling, was observed in both LER and HER of the virtual accelerator. Since there was higher beta beating in LER, focus was shifted to the improvement of this ring. By adjusting select quadrupoles of the virtual LER and fitting the resulting beta functions and phase advances to those of the desired lattice, the average beta beat of the virtual machine was effectively reduced. The new magnet configuration was dialed into LER on August 10, 2006, and beta beat was reduced by a factor of three. After fine tuning HER to match the improved LER for optimal collision, a record peak luminosity of 12.069 x 10 33 cm -2 s -1 was attained on August 16, 2006

e sup + e sup - Factories: PEP-II, KEKB, DAPHINE

CERN Document Server

Guiducci, S

2001-01-01

In 1999 two B-factories, PEP-II and KEK, and a PHI-factory, DAPHINE, started their physics experiments. A status report of the three factories is presented. A description of the interaction regions, strongly influenced by the detector requirements, and of the machine background in the detectors is presented.

Swamp plots for dynamic aperture studies of PEP-II lattices

International Nuclear Information System (INIS)

Yan, Y.T.; Irwin, J.; Cai, Y.; Chen, T.; Ritson, D.

1995-01-01

With a newly developed algorithm using resonance basis Lie generators and their evaluation with action-angle Poisson bracket maps (nPB tracking) the authors have been able to perform fast tracking for dynamic aperture studies of PEP-II lattices as well as incorporate lattice nonlinearities in beam-beam studies. They have been able to better understand the relationship between dynamic apertures and the tune shift and resonance coefficients in the generators of the one-turn maps. To obtain swamp plots (dynamic aperture vs. working point) of the PEP-II lattices, they first compute a one-turn resonance basis map for a nominal working point and then perform nPB tracking by switching the working point while holding fixed all other terms in the map. Results have been spot-checked by comparing with element-by-element tracking

An asymmetric Β-factory based on PEP

International Nuclear Information System (INIS)

Oddone, P.

1989-01-01

This paper reviews the motivation for building asymmetric B-factories based on storage rings and describes the current LBL/SLAC study to develop such a factory by modifying the PEP storage ring and adding a new low energy (2.5-3 GeV) storage ring. Collisions between the beam of the modified high energy PEP ring and the low energy ring lead to a luminosity of 2 x 10 33 cm- 2 sec - 1 at E cm = Y(4s) with currents of 0.8A in each beam. Further increases in current can lead to luminosities close to 10 34 cm - 2 sec - 1

PEP-II Beta Beat Fixes with MIA

International Nuclear Information System (INIS)

Yan, Y

2004-01-01

We first find a virtual accelerator for the HER or the LER through determination of all quadrupole strengths and sextupole feed-downs as well as all BPM gains and BPM cross-plane couplings by an SVD-enhanced Least-squares fitting of the quantities derivable from a complete set of orbits. These quantities are the phase advances, the Green's functions, and the tilt angles and axis ratios of the coupling eigen ellipses. They are obtained by analyzing turn-by-turn Beam Position Monitor (BPM) data with a high-resolution model-independent analysis (MIA). Once the virtual accelerator is found, we select a limited number of key quadrupoles, for example, the linear trombone quadrupoles and the global skews, for Least-square fitting of their strengths to minimize the beta beat while keeping other optics characters unchanged if not improved. We then dial in these limited number of quadrupole strength changes to the real accelerator (HER or LER) to achieve a better-performance PEP-II. Noticeable achievement by this MIA technique has been that MIA has helped PEP-II achieve its breaking record peak luminosity of 6.5 x 10 33 cm -2 s -1 in 2003 by bringing the LER working tune to near half integer and simultaneously fixing the beta beat, which would, otherwise, be difficult without MIA because of the strong LER coupling effect

Present and future colliding beam facilities at SLAC

International Nuclear Information System (INIS)

Wiedemann, H.

1977-07-01

In April 1972, the 3-GeV electron positron storage ring, SPEAR, was put into operation at the end of the linear accelerator at Stanford. By the recent discoveries in high energy physics the value of electron-positron storage rings for high energy physics has been clearly demonstrated. This development certainly encouraged the relatively early funding of the new electron-positron storage ring, PEP, at SLAC. In addition to its role as a particle physics research tool, SPEAR has been and remains a priceless model or prototype for larger storage rings like PEP. A few of the recent observations in SPEAR which have important implications to the design of PEP are described. Although the PEP design follows closely the SPEAR concept in many respects, it has its own distinctive and important features which are discussed in detail. Topics discussed include synchrotron-betatron resonances, beam losses, beam bunching, PEP design luminosity and energy, chromaticity correction in PEP, and the high energy cabability of PEP

PEP-II RF feedback system simulation

Energy Technology Data Exchange (ETDEWEB)

Tighe, R [Stanford Linear Accelerator Center, Menlo Park, CA (United States)

1996-08-01

A model containing the fundamental impedance of the PEP-II cavity along with the longitudinal beam dynamics and RF feedback system components is in use. It is prepared in a format allowing time-domain as well as frequency-domain analysis and full graphics capability. Matlab and Simulink are control system design and analysis programs (widely available) with many built-in tools. The model allows the use of compiled C-code modules for compute intensive portions. We desire to represent as nearly as possible the components of the feedback system including all delays, sample rates and applicable nonlinearities. (author)

Probing the structure of matter with Stanford's new $78 million high-energy accelerator

International Nuclear Information System (INIS)

Nolan, G.

1981-01-01

The US high-energy physics program recently gained a powerful new experimental tool with the completion of the Positron Electron Project (PEP). PEP is a colliding beam storage ring two kilometres in circumference. Collisions are obtained in the PEP ring by injecting electrons and positrons from SLAC's existing linear accelerator so that they circulate in opposite directions. At 6 points in the ring the beams will collide. PEP will enable collisions to be produced at up to 36 GeV

Beam-beam dynamics during the injection process at the PEP-II B-Factory

International Nuclear Information System (INIS)

Chin, Yong Ho.

1991-10-01

This paper is concerned with beam-beam effects during the injection process at the proposed asymmetric SLAC/LBL/LLNL B-Factory based on PEP (PEP-2). For symmetric colliders, the primary source of the beam-beam effect is the head-on collision at the interaction point (IP), and this effect can be mitigated by separating the beams during the injection process. For an asymmetric collider, which intrinsically consists of two separate rings, the bunches not only collide at the IP but experience a long-range beam-beam force on the way into and out of the IP region. These collisions are called ''parasitic crossings (PC).'' The parasitic crossings emerge as a potential source of far stronger beam-beam impact during the injection process for the following reason. In the proposed injection scheme of the APIARY-6.3d design, the bunches are injected horizontally into the two rings with large horizontal offset of 8σ Ox sptm where σ Ox sptm is the nominal horizontal storage ring beam size at the end of the septum magnet. Then, the injected beam starts to travel around the ring oscillating horizontally. For the sake of discussion, let us assume that the beam in the other ring has already been fully stored. When the injected beam arrives at the 1st PC, where the two nominal orbits are separated horizontally by about 7.6 times the nominal horizontal beam size of the low energy ring, it may pass through the other beam far more closely than at the nominal separation distance, or it may even strike the other beam head-on

P.E.P

International Nuclear Information System (INIS)

Paterson, J.M.

1980-07-01

The design and construction of the PEP project is briefly reviewed. The initial testing of the storage ring system and its present performance is described. The short-range plans for continuing development are discussed

Letter of intent for the study of CP violation and heavy flavor physics at PEP-II

Energy Technology Data Exchange (ETDEWEB)

BaBar Collaboration

1994-06-18

This report discusses the following topics on CP violation and heavy flavor physics experiments: Physics at PEP-II; detector overview; PEP-II and the interaction region; vertex detector; main tracking chamber; particle identification; electromagnetic calorimeter; muon and neutral hadron detector; magnet coil and flux return; electronics, trigger, and data acquisition; computing; CP asymmetry simulations; collaboration issues; project organization and management; and budget and schedule.

Letter of intent for the study of CP violation and heavy flavor physics at PEP-II

International Nuclear Information System (INIS)

1994-01-01

This report discusses the following topics on CP violation and heavy flavor physics experiments: Physics at PEP-II; detector overview; PEP-II and the interaction region; vertex detector; main tracking chamber; particle identification; electromagnetic calorimeter; muon and neutral hadron detector; magnet coil and flux return; electronics, trigger, and data acquisition; computing; CP asymmetry simulations; collaboration issues; project organization and management; and budget and schedule

Test results of pre-production prototype distributed ion pump design for the PEP-II Asymmetric B-Factory collider

Energy Technology Data Exchange (ETDEWEB)

Holdener, F.R.; Behne, D.; Hathaway, D. [and others

1995-04-24

We have built and tested a plate-type pre-production distributed Ion Pump (DIP) for the PEP-II B-Factory High Energy Ring (HER). The design has been an earlier design to use less materials and to costs. Penning cell hole sizes of 15, 18, and 21 mm have been tested in a uniform magnetic field of 0.18 T to optimize pumping speed. The resulting final DIP design consisting of a 7-plate, 15 mm basic cell size anode was magnetic field of the HER dipole. A description of the final optimized DIP design will be presented along with the test results of the pumping speed measurements.

PEP-II vacuum system pressure profile modeling using EXCEL

International Nuclear Information System (INIS)

Nordby, M.; Perkins, C.

1994-06-01

A generic, adaptable Microsoft EXCEL program to simulate molecular flow in beam line vacuum systems is introduced. Modeling using finite-element approximation of the governing differential equation is discussed, as well as error estimation and program capabilities. The ease of use and flexibility of the spreadsheet-based program is demonstrated. PEP-II vacuum system models are reviewed and compared with analytical models

Effect of the Electron Cloud and CSR on the Upgrade of the PEP-II

International Nuclear Information System (INIS)

Heifets, Samuel A

2001-01-01

Effects of the electron cloud and of the coherent synchrotron radiation (CSR) on the possible upgrade of the PEP-II B-factory are studied. PEP-II B factory operates with parameters shown in Table 1 and already exceeds the design luminosity. Nevertheless, a possibility of upgrading the machine to even higher luminosities is under consideration [1]. Several scenarios are summarized in Table 2. This paper describes effects of the electron cloud and of the coherent synchrotron radiation (CSR) on the proposed upgrades of the PEP-II B-factory. The first effect was observed [3] and caused [4] the degradation of the emittance at KEK B-factory. The analytic expression for the e-wake [2] is used in calculations of the head-tail instability. Other obvious effects of higher beam currents such as additional heat load are not considered. The short wave length CSR has been recently observed at Brookhaven [6]. Consideration of the effect of such CSR on the beam dynamics is based on our previous paper [7

PEP liquid level system

International Nuclear Information System (INIS)

Lauritzen, T.; Sah, R.C.

1981-03-01

A liquid level system has been installed in the accelerator housing of the PEP storage ring. This instrument spans the entire 2.2 km circumference of the PEP project, and over one hundred readouts provide reference elevations which are used for the accurate alignment of accelerator components. The liquid level has proven to be extremely precise (+-0.10 mm) and quick to use, and it has contributed to the accurate alignment of PEP before beam turn-on. Since the liquid level readouts are rigidly attached to the accelerator housing, the liquid level has been a convenient means to monitor the settling of the accelerator housing

PEP-II RF cavity revisited

International Nuclear Information System (INIS)

Rimmer, R.A.; Koehler, G.; Li, D.; Hartman, N.; Folwell, N.; Hodgson, J.; Ko, K.; McCandless, B.

1999-01-01

This report describes the results of numerical simulations of the PEP-II RF cavity performed after the completion of the construction phase of the project and comparisons are made to previous calculations and measured results. These analyses were performed to evaluate new calculation techniques for the HOM distribution and RF surface heating that were not available at the time of the original design. These include the use of a high frequency electromagnetic element in ANSYS and the new Omega 3P code to study wall losses, and the development of broadband time domain simulation methods in MAFIA for the HOM loading. The computed HOM spectrum is compared with cavity measurements and observed beam-induced signals. The cavity fabrication method is reviewed, with the benefit of hindsight, and simplifications are discussed

Design and analysis of a wiggler magnet system for the PEP-II B-Factory LER

International Nuclear Information System (INIS)

Heim, J.; Kendall, M.; Bertolini, L.; Fackler, O.; O'Connor, T.; Swan, T.; Zholents, A.

1996-01-01

The Low Energy Ring (LER) of the PEP-II B-Factory will use a wiggler magnet system for emittance control and additional damping. The wiggler magnet system is a set of 11 individual iron core, water cooled, dipole magnets designed to operate at 1.6 T and generate 400 kW of synchrotron radiation. Space has been provided to add a second wiggler with an additional 400 kW of synchrotron radiation if more damping is needed in the future. A copper vacuum chamber is used with continuous antechambers connected to both sides of the beam chamber via slots. Synchrotron radiation dump surfaces and distributed vacuum pumping are located in both antechambers. The authors describe the design and analysis of the wiggler magnets and the salient features of the vacuum chamber and dumps

Electron--positron storage ring PETRA: plans and status

International Nuclear Information System (INIS)

Voss, G.A.

1977-01-01

Construction of the Electron-Positron Storage Ring PETRA was authorized October 20, 1975. At present most of the civil engineering work is completed and ring installation work is under way. All major components are on order and series production of bending magnets, quadrupoles, vacuum chambers and rf-resonators has started. Start-up of the machine is planned with a fourfold symmetry configuration with four active beam-beam interaction points. Five experimental facilities have been recommended for the first round of experiments scheduled to begin mid 79

Single wavelength standard wiggler for PEP

International Nuclear Information System (INIS)

Brunk, W.; Fischer, G.; Spencer, J.

1979-03-01

A 1lambda planar wiggler has been designed that will be used for the initial operation of the 4 to 18 GeV storage ring PEP. Three of these wigglers will be installed symmetrically around the ring at 120 0 intervals in three of six available 5 m straight sections with the purpose of providing: (1) beam size control to obtain better luminosities below 15 GeV, and (2) decreased damping times to obtain better injection rates at lower energies. Design goals are discussed and a description of the final system including cost estimates is given. Expected results and usage in PEP are discussed. Some possibilities for production of synchrotron radiation and beam monitoring with shorter wavelength, multiple-period wigglers at PEP energies are also discussed. Comparison to a wiggler now operating in SPEAR is given

Background sources and masks for Mark II detector at PEP

International Nuclear Information System (INIS)

Kadyk, J.

1981-06-01

The shielding masks currently at use in several of the current experiments at PEP are the result of an early organized effort to understand the sources of particle background expected at PEP, followed by the evolution of the conceptual designs into actual hardware. The degree and kind of background particle loading which could be tolerated was expected to differ significantly among the different experiments, and several designs emerged from the common study. Qualitatively, the types of radiations studied were, Synchrotron Radiation (SR), Beam Gas Bremsstrahlung (BGB), and, to a limited extent others, e.g., Electroproduction (EP). Calculations will be given of predicted occupancies in the pipe counter and other sensitive elements at small radius, since these will be most susceptible to the SR and BGB backgrounds. The calculations presented in this note are specific to the Mark II detector. Some general statements will be made first about the character of each of the various types of backgrounds considered, then some detailed calculations made for application to the Mark II detector

Vacuum system for the Stanford-LBL storage ring (PEP)

International Nuclear Information System (INIS)

Bostic, D.; Cummings, U.; Dean, N.; Jeong, B.; Jurow, J.

1975-03-01

The vacuum system for PEP will be similar in design, construction and operation to the system currently in operation at SPEAR. There will, of course, be quantitative differences since the closed path of PEP will be 10 times longer than the SPEAR path. Some qualitative differences will also arise since the radiated synchrotron power for PEP will be about 13 times greater than for SPEAR giving rise to an increased linear power density incident on the chamber wall. Other differences arise from the higher energy spectrum of the synchrotron radiation. The SPEAR vacuum system has been in operation since April 1972 and has proven satisfactory in design, construction and operation. The chamber has been subject to synchrotron radiation for approximately 300 ampere-hours and beam lifetimes are now more than several hours. The details of the PEP design and the SPEAR operating experience will be further discussed in this paper. 1 ref., 4 figs

Study of four-lepton final states in electron-positron interactions at 29 GeV

International Nuclear Information System (INIS)

Petradza, A.

1989-08-01

This thesis presents a study of electron-positron scattering to four light leptons. The motivations behind it are twofold. Firstly, the study is a test of the theory of electron-positron interactions to 4th order in the fine structure constant α. A deviation from the theory could indicate the existence of a heavy new particle. Secondly, a measurement of these processes may prove useful in the understanding of other QED-type reactions. The method for simulating the four-lepton processes by the Monte Carlo event generator of Berends, Daverveldt and Kleiss is described. Theoretical predictions are compared to data from the Mark II and HRS experiments at the PEP storage ring. The observed events consist of four leptons at large angles. Data for all three e + e - e + e - , e + e - μ + μ - and μ + μ - μ + μ - processes are well described by the QED Monte Carlo calculation. The various kinematical distributions are in good agreement with QED to order α 4 . 18 refs., 64 figs., 19 tabs

RF system design for the PEP-II B Factory

International Nuclear Information System (INIS)

Schwarz, H.; Rimmer, R.

1994-06-01

The paper presents an overview of the design of the RF system for the PEP-II B Factory. An RF station consists of either two or four single-cell cavities driven by a 1.2 MW klystron through a waveguide distribution network. A variety of feedback loops stabilize the RF and its interaction with the beam. System parameters and all the relevant parameters of klystron and cavities are given

Progress on PEP-II magnet power conversion system

International Nuclear Information System (INIS)

Bellomo, P.; Genova, L.; Jackson, T.; Shimer, D.

1996-01-01

The various power systems for supplying the PEP-II DC magnets rely exclusively on switchmode conversion, utilizing a variety of means depending on the requirements. All of the larger power supplies, ranging from 10 to 200 kW, are powered from DC sources utilizing rectified 480 V AC. Choppers can be used for the series connected strings, but for smaller groups and individual magnets, inverters driving high-frequency transformers with rectifiers comprise the best approach. All of the various systems use a ''building block'' approach of multiple standard-size units connected in series or parallel to most cost-effectively deal with a great range of voltage and current requirements. Utilization of existing infrastructure from PEP-I has been a cost-effective determinant. Equipment is being purchased either off-the-shelf, through performance specification, or by hardware purchase based on design-through-prototype. The corrector magnet power system, utilizing inexpensive, off-the-shelf, four-quadrant switching motor-controllers, has already proven very reliable: 120 of the total of 900 units have been running on the injection system for four months with no failures

Progress on PEP-II magnet power conversion system

Energy Technology Data Exchange (ETDEWEB)

Bellomo, P.; Genova, L. [Stanford Linear Accelerator Center, Menlo Park, CA (United States); Jackson, T. [Lawrence Berkeley National Lab., CA (United States); Shimer, D. [Lawrence Livermore National Lab., CA (United States)

1996-06-04

The various power systems for supplying the PEP-II DC magnets rely exclusively on switchmode conversion, utilizing a variety of means depending on the requirements. All of the larger power supplies, ranging from 10 to 200 kW, are powered from DC sources utilizing rectified 480 V AC. Choppers can be used for the series connected strings, but for smaller groups and individual magnets, inverters driving high-frequency transformers with rectifiers comprise the best approach. All of the various systems use a ``building block`` approach of multiple standard-size units connected in series or parallel to most cost-effectively deal with a great range of voltage and current requirements. Utilization of existing infrastructure from PEP-I has been a cost-effective determinant. Equipment is being purchased either off-the-shelf, through performance specification, or by hardware purchase based on design-through-prototype. The corrector magnet power system, utilizing inexpensive, off-the-shelf, four-quadrant switching motor-controllers, has already proven very reliable: 120 of the total of 900 units have been running on the injection system for four months with no failures.

BABAR - the detector for the PEP II B Factory at SLAC

International Nuclear Information System (INIS)

Lueth, V.

1994-09-01

BABAR refers to the detector that is being designed for the PEP II B-Factory at SLAC to perform a comprehensive study of CP violation in B meson decays. The design requirements and the principal detector components are briefly described. A summary of the expected physics performance is presented

Test results of distributed ion pump designs for the PEP-II Asymmetric B-Factory collider

Energy Technology Data Exchange (ETDEWEB)

Calderon, M.; Holdener, F.; Peterson, D. [Lawrence Livermore National Lab., CA (United States)] [and others

1994-07-01

The testing facility measurement methods and results of prototype distributed ion pump (DIP) designs for the PEP-II B-Factory High Energy Ring are presented. Two basic designs with 5- or 7-anode plates were tested at LLNL with penning cell sizes of 15, 18, and 21 mm. Direct comparison of 5- and 7-plate anodes with 18 mm holes shows increased pumping speed with the 7-plate design. The 5-plate, 18 mm and 7-plate, 15 mm designs both gave an average pumping speed of 135 1/s/m at 1 {times} 10{sup {minus}8} Torr nitrogen base pressure in a varying 0.18 T peak B-field. Comparison of the three hole sizes indicates that cells smaller than the 15 mm tested can be efficiently used to obtain higher pumping speeds for the same anode plate sizes used.

Test results of distributed ion pump designs for the PEP-II Asymmetric B-Factory collider

International Nuclear Information System (INIS)

Calderon, M.; Holdener, F.; Peterson, D.

1994-07-01

The testing facility measurement methods and results of prototype distributed ion pump (DIP) designs for the PEP-II B-Factory High Energy Ring are presented. Two basic designs with 5- or 7-anode plates were tested at LLNL with penning cell sizes of 15, 18, and 21 mm. Direct comparison of 5- and 7-plate anodes with 18 mm holes shows increased pumping speed with the 7-plate design. The 5-plate, 18 mm and 7-plate, 15 mm designs both gave an average pumping speed of 135 1/s/m at 1 x 10 -8 Torr nitrogen base pressure in a varying 0.18 T peak B-field. Comparison of the three hole sizes indicates that cells smaller than the 15 mm tested can be efficiently used to obtain higher pumping speeds for the same anode plate sizes used

Rf systems for high-energy e/sup /minus//e/sup /plus// storage rings

International Nuclear Information System (INIS)

Allen, M.A.; Wilson, P.B.

1974-01-01

Electron or positron beams in a storage ring radiate electromagnetic energy at a rate proportional to the fourth power of the recirculating energy, and this loss must be supplied by an rf system. Furthermore, a substantial overvoltage is required to contain the stored beam against losses due to quantum fluctuations in the emitted photons. As an example, an improvement program, SPEAR II, is now underway to increase the energy of the SPEAR ring to 4.5 GeV. At this energy, the radiation loss per turn is 2.8 MeV, and to maintain a reasonable lifetime against quantum fluctuations, a peak voltage of 7.5 MeV is required. Thus, the SPEAR II rf system is similar to a continuously-operating 7.5 MeV linear accelerator. Furthermore, the available straight-section space in the ring which is suitable for containing the accelerating structures is limited, and this means that a cavity design must be sought with a high shunt impedance per losses will be held to a reasonable level. In the case of SPEAR, about 9 meters of straight section space is available for accelerating cavities, requiring a gradient of close to 1 MV per meter. The PEP 15-GeV ring would require peak accelerating voltages of around 50 MV, with about 60 meters of straight-section space available for accelerating structures. 8 refs

A Parallel Controls Software Approach for PEP II: AIDA and Matlab Middle Layer

International Nuclear Information System (INIS)

Wittmer, W.; Colocho, W.; White, G.

2007-01-01

The controls software in use at PEP II (Stanford Control Program - SCP) had originally been developed in the eighties. It is very successful in routine operation but due to its internal structure it is difficult and time consuming to extend its functionality. This is problematic during machine development and when solving operational issues. Routinely, data has to be exported from the system, analyzed offline, and calculated settings have to be reimported. Since this is a manual process, it is time consuming and error-prone. Setting up automated processes, as is done for MIA (Model Independent Analysis), is also time consuming and specific to each application. Recently, there has been a trend at light sources to use MATLAB as the platform to control accelerators using a 'MATLAB Middle Layer' (MML), and so called channel access (CA) programs to communicate with the low level control system (LLCS). This has proven very successful, especially during machine development time and trouble shooting. A special CA code, named AIDA (Accelerator Independent Data Access), was developed to handle the communication between MATLAB, modern software frameworks, and the SCP. The MML had to be adapted for implementation at PEP II. Colliders differ significantly in their designs compared to light sources, which poses a challenge. PEP II is the first collider at which this implementation is being done. We will report on this effort, which is still ongoing

Operation of PEP longitudinal feedback system

International Nuclear Information System (INIS)

Allen, M.A.; Karvonen, L.G.; McConnell, R.A.; Schwarz, H.

1981-03-01

In order to suppress longitudinal coupled-bunch oscillations which might limit the capabilities of PEP, the 18 GeV e + e - storage ring at SLAC, a longitudinal feedback system is utilized. A frequency domain feedback system was chosen with the frequency spectrum of the stored beam being sampled close to a symmetry point in the ring where the feedback cavity itself is also located. The symmetry point chosen is symmetry point 5 which lies half-way between interaction regions 4 and 6. The system has been installed in PEP and is now operational. However, at stored currents up to the maximum stored in PEP to date at 14.5 GeV (approximately 40 mA in 6 bunches), the ring has been stable to all modes of longitudinal coupled-bunch oscillations both barycentric and the other fundamental modes. By deliberately detuning the main accelerating cavities, small multibunch oscillations can be introduced which, in turn, can be damped by the feedback system. Under optimized beam conditions the feedback system could be adjusted to positive feedback and excite oscillations with relatively small power to the feedback cavity. This will be described along with other details of the system

Positron annihilation imaging device using multiple offset rings of detectors

International Nuclear Information System (INIS)

Thompson, C.J.

1982-01-01

A means is provided for recording more than one tomographic image simultaneously through different cross-sections of a patient, using positron emission tomography. Separate rings of detectors are used to construct every odd-numbered slice, and coincident events that occur between adjacent rings of detectors provide a center or even-numbered slice. Detector rings are offset with respect to one another by half the angular separation of the detectors, allowing an image to be reconstructed from the central slice without the necessity of physically rotating the detector array while accumulating data

PEP cooling water systems and underground piped utilities design criteria report

International Nuclear Information System (INIS)

Hall, F.; Robbins, D.

1975-10-01

This paper discusses the cooling systems required by the PEP Storage Ring. Particular topics discussed are: Cooling tower systems, RF cavity and vacuum chamber LCW cooling systems, klystron and ring magnet LLW cooling systems, Injection magnet LCW Cooling Systems; PEP interaction area detector LCW Cooling Systems; and underground piped utilities. 1 ref., 20 figs

Plans for PEP survey and alignment: Status report

International Nuclear Information System (INIS)

Gunn, J.; Sah, R.

1975-01-01

This note discusses the current state of survey and alignment plans for PEP Stage I. Several surveying techniques are described; one is described in considerable detail. The survey and alignment task for PEP consists of positioning approximately 700 ring magnets, 100 injection line magnets, and 100 miscellaneous components. The alignment tolerances are tight and they are set by the requirement that closed orbit distortions must be small for proper storage ring operation. The alignment problem is aggravated by the circumstance that the storage ring components are placed in tunnels which span a large area (over 700 meters across) and which do not permit long lines of sight. 6 ref., 1 fig

Fabrication process for the PEP II RF cavities

Energy Technology Data Exchange (ETDEWEB)

Franks, R.M.; Rimmer, R.A. [Lawrence Berkeley National Lab., CA (United States); Schwarz, H. [Stanford Linear Accelerator Center, Menlo Park, CA (United States)

1997-06-05

This paper presents the major steps used in the fabrication of the 26 RF Cavities required for the PEP-II B-factory. Several unique applications of conventional processes have been developed and successfully implemented: electron beam welding (EBW), with minimal porosity, of .75 inch (19 mm) copper cross-sections; extensive 5-axis milling of water channels; electroplating of .37 inch (10 mm) thick OFE copper; tuning of the cavity by profiling beam noses prior to final joining with the cavity body; and machining of the cavity interior, are described here.

The PEP-II/BaBar Project-Wide Database using World Wide Web and Oracle*Case

International Nuclear Information System (INIS)

Chan, A.; Crane, G.; MacGregor, I.; Meyer, S.

1995-12-01

The PEP-II/BaBar Project Database is a tool for monitoring the technical and documentation aspects of the accelerator and detector construction. It holds the PEP-II/BaBar design specifications, fabrication and installation data in one integrated system. Key pieces of the database include the machine parameter list, components fabrication and calibration data, survey and alignment data, property control, CAD drawings, publications and documentation. This central Oracle database on a UNIX server is built using Oracle*Case tools. Users at the collaborating laboratories mainly access the data using World Wide Web (WWW). The Project Database is being extended to link to legacy databases required for the operations phase

Optimization of Dynamic Aperture of PEP-X Baseline Design

Energy Technology Data Exchange (ETDEWEB)

Wang, Min-Huey; /SLAC; Cai, Yunhai; /SLAC; Nosochkov, Yuri; /SLAC

2010-08-23

SLAC is developing a long-range plan to transfer the evolving scientific programs at SSRL from the SPEAR3 light source to a much higher performing photon source. Storage ring design is one of the possibilities that would be housed in the 2.2-km PEP-II tunnel. The design goal of PEPX storage ring is to approach an optimal light source design with horizontal emittance less than 100 pm and vertical emittance of 8 pm to reach the diffraction limit of 1-{angstrom} x-ray. The low emittance design requires a lattice with strong focusing leading to high natural chromaticity and therefore to strong sextupoles. The latter caused reduction of dynamic aperture. The dynamic aperture requirement for horizontal injection at injection point is about 10 mm. In order to achieve the desired dynamic aperture the transverse non-linearity of PEP-X is studied. The program LEGO is used to simulate the particle motion. The technique of frequency map is used to analyze the nonlinear behavior. The effect of the non-linearity is tried to minimize at the given constrains of limited space. The details and results of dynamic aperture optimization are discussed in this paper.

Optimization of Dynamic Aperture of PEP-X Baseline Design

International Nuclear Information System (INIS)

Wang, Min-Huey

2010-01-01

SLAC is developing a long-range plan to transfer the evolving scientific programs at SSRL from the SPEAR3 light source to a much higher performing photon source. Storage ring design is one of the possibilities that would be housed in the 2.2-km PEP-II tunnel. The design goal of PEPX storage ring is to approach an optimal light source design with horizontal emittance less than 100 pm and vertical emittance of 8 pm to reach the diffraction limit of 1-(angstrom) x-ray. The low emittance design requires a lattice with strong focusing leading to high natural chromaticity and therefore to strong sextupoles. The latter caused reduction of dynamic aperture. The dynamic aperture requirement for horizontal injection at injection point is about 10 mm. In order to achieve the desired dynamic aperture the transverse non-linearity of PEP-X is studied. The program LEGO is used to simulate the particle motion. The technique of frequency map is used to analyze the nonlinear behavior. The effect of the non-linearity is tried to minimize at the given constrains of limited space. The details and results of dynamic aperture optimization are discussed in this paper.

Calibration of the beam-position monitor system for the SLAC PEP-II B factory

International Nuclear Information System (INIS)

Johnson, R.; Smith, S.; Kurita, N.

1997-06-01

The Beam-Position Monitors (BPM) for the PEP-II B Factory consist of four 1.5-cm diameter button style pickups mounted on the diagonals of the quadrupole vacuum chambers. Before installation of the vacuum chambers in the quadrupole assemblies, the electrical center of the BPMs is measured with respect to the mechanical center in a calibration test stand. In this paper the calibration test stand is described and the precision and accuracy of the calibrations are presented. After installation of the quadrupole assemblies in the PEP-II tunnel, the passive attenuation for each channel of the system is measured to preserve the accuracy of the calibration. Finally, the active electronics includes an onboard calibrator. Results for these portions of the calibration are presented

PEP-II Transverse Feedback Electronics Upgrade

International Nuclear Information System (INIS)

Weber, J.; Chin, M.; Doolittle, L.; Akre, R.

2005-01-01

The PEP-II B Factory at the Stanford Linear Accelerator Center (SLAC) requires an upgrade of the transverse feedback system electronics. The new electronics require 12-bit resolution and a minimum sampling rate of 238 Msps. A Field Programmable Gate Array (FPGA) is used to implement the feedback algorithm. The FPGA also contains an embedded PowerPC 405 (PPC-405) processor to run control system interface software for data retrieval, diagnostics, and system monitoring. The design of this system is based on the Xilinx(R) ML300 Development Platform, a circuit board set containing an FPGA with an embedded processor, a large memory bank, and other peripherals. This paper discusses the design of a digital feedback system based on an FPGA with an embedded processor. Discussion will include specifications, component selection, and integration with the ML300 design

PEP-II Transverse Feedback Electronics Upgrade

International Nuclear Information System (INIS)

Weber, J.M.; Chin, M.J.; Doolittle, L.R.; Akre, R.

2006-01-01

The PEP-II B Factory at the Stanford Linear Accelerator Center (SLAC) requires an upgrade of the transverse feedback system electronics. The new electronics require 12-bit resolution and a minimum sampling rate of 238 Msps. A Field Programmable Gate Array (FPGA) is used to implement the feedback algorithm. The FPGA also contains an embedded PowerPC 405 (PPC-405) processor to run control system interface software for data retrieval, diagnostics, and system monitoring. The design of this system is based on the Xilinx(reg s ign) ML300 Development Platform, a circuit board set containing an FPGA with an embedded processor, a large memory bank, and other peripherals. This paper discusses the design of a digital feedback system based on an FPGA with an embedded processor. Discussion will include specifications, component selection, and integration with the ML300 design

PEP-II Transverse Feedback Electronics Upgrade

CERN Document Server

Weber, Jonah; Chin, Michael; Doolittle, Lawrence

2005-01-01

The PEP-II B Factory at the Stanford Linear Accelerator Center (SLAC) requires an upgrade of the transverse feedback system electronics. The new electronics require 12-bit resolution and a minimum sampling rate of 238 Msps. A Field Programmable Gate Array (FPGA) is used to implement the feedback algorithm. The FPGA also contains an embedded PowerPC 405 (PPC-405) processor to run control system interface software for data retrieval, diagnostics, and system monitoring. The design of this system is based on the Xilinx® ML300 Development Platform, a circuit board set containing an FPGA with an embedded processor, a large memory bank, and other peripherals. This paper discusses the design of a digital feedback system based on an FPGA with an embedded processor. Discussion will include specifications, component selection, and integration with the ML300 design.

Operation and performance of the PEP-II prototype longitudinal damping system at ALS

International Nuclear Information System (INIS)

Teytelman, D.; Claus, R.; Fox, J.

1995-05-01

A modular programmable longitudinal feedback system has been developed as a component of the PEP-II R+D program. This system is based on a family of VME and VXI packaged signal processing functions which implement a general purpose digital feedback controller for accelerators with bunch spacings of 2 ns. A complete PEP-II prototype system has been configured and installed for use at the LBL Advanced Light Source. The system configuration used for tests at the ALS is described and results are presented showing the action of the feedback system. Open and closed loop results showing the detection and calculation of feedback signals from bunch motion are presented and the system is shown to damp coupled-bunch instabilities in the ALS. Use of the system for accelerator diagnostics is illustrated via measurement of grow-damp transients which quantify growth rates without feedback, damping rates with feedback, and identify unstable modes

TRACKING SIMULATIONS NEAR HALF-INTEGER RESONANCE AT PEP-II

International Nuclear Information System (INIS)

Nosochkov, Yuri

2003-01-01

Beam-beam simulations predict that PEP-II luminosity can be increased by operating the horizontal betatron tune near and above a half-integer resonance. However, effects of the resonance and its synchrotron sidebands significantly enhance betatron and chromatic perturbations which tend to reduce dynamic aperture. In the study, chromatic variation of horizontal tune near the resonance was minimized by optimizing local sextupoles in the Interaction Region. Dynamic aperture was calculated using tracking simulations in LEGO code. Dependence of dynamic aperture on the residual orbit, dispersion and β distortion after correction was investigated

Modeling Lost-Particle Accelerator Backgrounds in PEP-II Using LPTURTLE

CERN Document Server

Fieguth, Theodore; Kozanecki, Witold

2005-01-01

Background studies during the design, construction, commissioning, operation and improvement of BaBar and PEP-II have been greatly influenced by results from a program referred to as LPTURTLE (Lost Particle TURTLE a modified version of Decay TURTLE) which was originally conceived for the purpose of studying gas background for SLC. This venerable program is still in use today. We describe its use, capabilities and improvements and refer to current results now being applied to BaBar.

In Depth Diagnostics for RF System Operation in the PEP-II B Factory

International Nuclear Information System (INIS)

Van Winkle, Daniel; Fox, John; Teytelman, Dmitry; SLAC

2005-01-01

The PEP-II RF systems incorporate numerous feedback loops in the low-level processing for impedance control and operating point regulation. The interaction of the multiple loops with the beam is complicated, and the systems incorporate online diagnostic tools to configure the feedback loops as well as to record fault files in the case of an RF abort. Rapid and consistent analysis of the RF-related beam aborts and other failures is critical to the reliable operation of the B-Factory, especially at the recently achieved high beam currents. Procedures and algorithms used to extract diagnostic information from time domain fault files are presented and illustrated via example interpretations of PEP-II fault file data. Example faults presented will highlight the subtle interpretation required to determine the root cause. Some such examples are: abort kicker firing asynchronously, klystron and cavity arcs, beam loss leading to longitudinal instability, tuner read back jumps and poorly configured low-level RF feedback loop

Design and alaysis of the PEP-II B-Factory HER QF5 quadrupole magnet

International Nuclear Information System (INIS)

Kendall, C.M.; Harvey, A.; Swan, J.; Yamamoto, R.; Yokota, T.; Tanabe, J.; Sullivan, M.; Wienands, U.

1997-01-01

The High Energy Ring (HER) in Stanford Linear Accelerator Center's PEP-II B-Factory employs two high field quality quadrupole magnets, labeled QF5, located in the Interaction Region (IR) symmetrically about the Interaction Point (IP), for final horizontal beam focusing. An asymmetric, septum, Collins quadrupole design is required for QF5 as a result of space constraints within the IR. Water cooled square hollow copper conductor is used in a two coil per pole configuration to develop the 61.7 kG/m and 82.2 kG/m gradients required for the HER 9 GeV and 12 GeV energy levels respectively. A 1.45 m long laminated iron core constructed in two halves with a 160 mm diameter aperture and pole tip shims shape the quadruple field. The QF5 field quality requirements include a multipole content of b n /b 2 ≤1 x 10 -4 for n = 3-15 at a radius of 78.1 mm. The QF5 quadrupole mechanical and magnetic design and analysis are presented

Estimate of coherent tune shifts for PEP

International Nuclear Information System (INIS)

Yao, C.Y.; Chao, A.W.

1981-02-01

Transverse and longitudinal instabilities for a bunched PEP beam with a Gaussian distribution are treated using the standard technique in which instability problems are solved by looking for eigenvalues of the linearized Vlasov equation. The eigen solutions are conveniently expanded in terms of the Laquerre polynomials, and the eigenvalues are given by a symmetric matrix whose elements can be expressed in infinite series. The well-known formalism is used to obtain the matrix formula, and then applied numerically to the PEP ring to estimate the transverse coherent tune shifts. The impedance used is that estimated for the PEP RF cavities. The agreement with experimental data seems reasonable

PEP-II RF Cavity Revisited (LCC-0032)

Energy Technology Data Exchange (ETDEWEB)

Rimmer, R.

2004-03-23

This report describes the results of numerical simulations of the PEP-II RF cavity performed after the completion of the construction phase of the project and comparisons are made to previous calculations and measured results. These analyses were performed to evaluate new calculation techniques for the HOM distribution and RF surface heating that were not available at the time of the original design. These include the use of a high frequency electromagnetic element in ANSYS and the new Omega 3P code to study wall losses, and the development of broadband time domain simulation methods in MAFIA for the HOM loading. The computed HOM spectrum is compared with cavity measurements and observed beam-induced signals. The cavity fabrication method is reviewed, with the benefit of hindsight, and simplifications are discussed.

Development of a Single Detector Ring Micro Crystal Element Scanner: QuickPET II

Directory of Open Access Journals (Sweden)

Robert S. Miyaoka

2005-04-01

Full Text Available This article describes a single ring version of the micro crystal element scanner (MiCES and investigation of its spatial resolution imaging characteristics for mouse positron emission tomography (PET imaging. This single ring version of the MiCES system, referred to as QuickPET II, consists of 18 MiCE detector modules mounted as a single ring in a vertical gantry. The system has a 5.76-cm transverse field of view and a 1.98-cm axial field of view. In addition to the scanner and data acquisition system, we have developed an iterative reconstruction that includes a model of the system's detector response function. Evaluation images of line sources and mice have been acquired. Using filtered backprojection, the resolution for a reconstructed line source has been measured at 1.2 mm full width at half maximum. F-18-2-fluoro-2-deoxyglucose mouse PET images are provided. The result shows that QuickPET II has the imaging characteristics to support high-resolution, static mouse PET studies using 18-F labeled compounds.

The efficacy of chimeric vaccines constructed with PEP-1 and Ii-Key linking to a hybrid epitope from heterologous viruses.

Science.gov (United States)

Liu, Xue-lan; Shan, Wen-jie; Xu, Shan-shan; Zhang, Jin-jing; Xu, Fa-zhi; Xia, Sheng-lin; Dai, Yin

2015-09-01

The heterologous epitope-peptide from different viruses may represent an attractive candidate vaccine. In order to evaluate the role of cell-permeable peptide (PEP-1) and Ii-Key moiety from the invariant chain (Ii) of MHC on the heterologous peptide chimeras, we linked the two vehicles to hybrid epitopes on the VP2 protein (aa197-209) of the infectious bursal disease virus and HN protein (aa345-353) of the Newcastle disease virus. The chimeric vaccines were prepared and injected into mice. The immune effects were measured by indirect ELISA. The results showed that the vehicle(s) could significantly boost immune effects against the heterologous epitope peptide. The Ii-Key-only carrier induced more effective immunological responses, compared with the PEP-1 and Ii-Key hybrid vehicle. The carrier-peptide hybrids all showed strong colocalization with major histocompatibility complex (MHC) class II molecules compared with the epitope-peptide (weakly-binding) after co-transfection into 293T cells. Together, our results lay the groundwork for designing new hybrid vaccines based on Ii-Key and/or PEP-1 peptides. Copyright © 2015 The International Alliance for Biological Standardization. Published by Elsevier Ltd. All rights reserved.

RF feedback development for the PEP-II B Factory

Energy Technology Data Exchange (ETDEWEB)

Corredoura, P.; Sapozhnikov, L.; Tighe, R.

1994-06-01

In PEP-II heavy beam loading along with a relatively long revolution period combine to strongly drive lower coupled-bunch modes through interaction with the fundamental cavity mode. Feedback techniques can be applied to reduce the cavity impedance seen by the beam. Several RF feedback loops are planned to reduce the growth rates down to a level which can be damped by the relatively low power bunch-by-bunch longitudinal feedback system. This paper describes the RF feedback loops as well as hardware tests using a 500 kW klystron, analog and digital feedback loops, and a low power test cavity.

RF feedback development for the PEP-II B Factory

International Nuclear Information System (INIS)

Corredoura, P.; Sapozhnikov, L.; Tighe, R.

1994-06-01

In PEP-II heavy beam loading along with a relatively long revolution period combine to strongly drive lower coupled-bunch modes through interaction with the fundamental cavity mode. Feedback techniques can be applied to reduce the cavity impedance seen by the beam. Several RF feedback loops are planned to reduce the growth rates down to a level which can be damped by the relatively low power bunch-by-bunch longitudinal feedback system. This paper describes the RF feedback loops as well as hardware tests using a 500 kW klystron, analog and digital feedback loops, and a low power test cavity

Lessons learned from positron-electron project low level rf and longitudinal feedback

Directory of Open Access Journals (Sweden)

J. Fox

2010-05-01

Full Text Available The Positron-Electron Project II (PEP-II B Factory collider ended the final phase of operation at nearly twice the design current and 4X the design luminosity. In the ultimate operation state, eight 1.2 MW radio-frequency (rf klystrons and 12 accelerating cavities were added beyond the original implementation, and the two storage rings were operating with longitudinal instability growth rates roughly 5X in excess of the original design estimates. From initial commissioning there has been continual adaptation of the low level rf (LLRF control strategies, configuration tools, and some new hardware in response to unanticipated technical challenges. This paper offers a perspective on the original LLRF and longitudinal instability control design, and highlights via two examples the system evolution from the original design estimates through to the final machine with 1.2×10^{34} luminosity. The impact of unanticipated signals in the coupled-bunch longitudinal feedback and the significance of nonlinear processing elements in the LLRF systems are presented. We present valuable “lessons learned” which are of interest to designers of next generation feedback and impedance controlled LLRF systems.

The Cornell electron-positron storage ring - CESR

International Nuclear Information System (INIS)

DeWire, J.W.

1977-01-01

At the Laboratory of Nuclear Studies of Cornell University we are working on a project to convert the present 12 GeV electron synchrotron complex into the Cornell Electron-Positron Storage Ring - CESR. The design studies for this new device were begun in early 1975. During the past eighteen months the National Science Foundation has supported a program of research and development on CESR and funds to begin construction are included in the NSF budget now before the U.S. Congress. Our goal is to have CESR in operation in the fall of 1979. (orig.) [de

Study of heavy quark production with the Mark II at PEP

International Nuclear Information System (INIS)

Abrams, G.; Amidei, D.; Baden, A.

1983-10-01

The methods adopted by the Mark II collaboration to study heavy quark production at PEP are described. Two complementary techniques are used: D* tagging using the decay chain D* + . D 0 π + , D 0 → K - π + , and inclusive lepton tagging using the characteristic p/sub T/ distributions to distinguish contributions from b and c quarks. These techniques are used to derive information about heavy quark fragmentation and about the weak coupling of heavy quarks

Dual Power Supplies for PEP-II Injection Kickers

CERN Document Server

Olszewski, Joseph; Iverson, Richard; Kulikov, Artem; Pappas, Chris

2005-01-01

Originally the PEP-II injection kickers where powered by one power supply. Since the kicker magnets where not perfectly matched, the stored beam got excited by about 7% of the maximum kicker amplitude. This led to luminosity losses which were especially obvious for trickle injection when the detector is on for data taking. Therefore two independant power supplies with thyratrons in the tunnel next to the kicker magnet were installed. This also reduces the necessary power by about a factor of five since there are no long cables that have to be charged. The kickers are now independantly adjustable to eliminate any non-closure of the kicker system and therefore excitation of the stored beam. Setup, commissioning and fine tuning of this system are discussed.

Dual Power Supplies for PEP-II Injection Kickers

Energy Technology Data Exchange (ETDEWEB)

Olszewski, J; Decker, F.-J.; Iverson, R.H.; Kulikov, A.; Pappas, C.; /SLAC

2005-05-25

Originally the PEP-II injection kickers were powered by one power supply. Since the kicker magnets where not perfectly matched, the stored beam got excited by about 7% of the maximum kicker amplitude. This led to luminosity losses which were especially obvious for trickle injection when the detector is on for data taking. Therefore two independent power supplies with thyratrons in the tunnel next to the kicker magnet were installed. This also reduces the necessary power by about a factor of four since there are no long cables that have to be charged. The kickers are now independently adjustable to eliminate any non-closure of the kicker system and therefore excitation of the stored beam. Setup, commissioning and fine tuning of this system are discussed.

Dual Power Supplies for PEP-II Injection Kickers

International Nuclear Information System (INIS)

Olszewski, J; Decker, F.-J.; Iverson, R.H.; Kulikov, A.; Pappas, C.; SLAC

2005-01-01

Originally the PEP-II injection kickers were powered by one power supply. Since the kicker magnets where not perfectly matched, the stored beam got excited by about 7% of the maximum kicker amplitude. This led to luminosity losses which were especially obvious for trickle injection when the detector is on for data taking. Therefore two independent power supplies with thyratrons in the tunnel next to the kicker magnet were installed. This also reduces the necessary power by about a factor of four since there are no long cables that have to be charged. The kickers are now independently adjustable to eliminate any non-closure of the kicker system and therefore excitation of the stored beam. Setup, commissioning and fine tuning of this system are discussed

Demonstration of electron clearing effect by means of a clearing electrode in high-intensity positron ring

International Nuclear Information System (INIS)

Suetsugu, Y.; Fukuma, H.; Wang, L.; Pivi, M.; Morishige, A.; Suzuki, Y.; Tsukamoto, M.; Tsuchiya, M.

2009-01-01

In the beam pipe of high-intensity positron/proton storage rings, undesired electron clouds may be first produced by photoelectrons and the ionization of residual gases; then the clouds increase by the secondary electron emission. In this study, a strip-line clearing electrode has been developed to mitigate the electron-cloud effect in high-intensity positron/proton storage rings. The electrode is composed of a thin tungsten layer with a thickness of 0.1 mm formed on a thin alumina ceramic layer with a thickness of 0.2 mm. The narrow alumina gap between the electrode and the beam pipe decreases the beam impedance and also enhances the heat transfer from the electrode to the beam pipe. A test model has been installed in the KEK B-factory (KEKB) positron ring, along with an electron monitor with a retarding grid. The electron density in a field free region decreased by one order of magnitude was observed on the application of ±500 V to the electrode at a beam current of 1.6 A with 1585 bunches. The reduction in the electron density was more drastic in a vertical magnetic field of 0.77 T, that is, the electron density decreased by several orders by applying +500 V to the electrode at the same beam current. This experiment is the first experiment demonstrating the principle of the clearing electrode that is used to mitigate the electron-cloud effect in a positron ring.

Numerical simulation of the PEP-II beam position monitor

Energy Technology Data Exchange (ETDEWEB)

Kurita, N; Martin, D; Ng, C -K; Smith, S [Stanford Linear Accelerator Center, Menlo Park, CA (United States); Weiland, T

1996-08-01

We use MAFIA to analyze the PEP-II button-type beam position monitor (BPM). Employing proper termination of the BPM into a coaxial cable, the output signal at the BPM is determined. Thus the issues of signal sensitivity and power output can be addressed quantitatively, including all transient effects and wakefields. Besides this first quantitative analysis of a true BPM 3D structure, we find that internal resonant modes are a major source of high value narrow-band impedances. The effects of these resonances on coupled-bunch instabilities are discussed. An estimate of the power dissipation in the ceramic vacuum seal under high current operation is given. (author)

Beam-beam effects for the PEP-II B Factory

International Nuclear Information System (INIS)

Furman, M.A.; Eden, J.R.

1993-05-01

We present a summary of a fairly extensive study of beam-beam issues that arise in the design of PEP-II. Most of these studies are carried out with ''strong-strong'' multiparticle tracking simulations. We focus on: choice of nominal beam-beam parameter, strength of the parasitic collisions, injection issues, performance and tradeoffs with unequal beam-beam parameters. We comment only briefly on beam lifetime. We conclude that: the beams are sufficiently well separated so that the parasitic collisions are effectively weak; that small inequalities in the beam-beam parameters may imply more comfortable performance margins; and that vertical injection with vertical beam separation is more comfortable than horizontal

Numerical simulation of the PEP-II beam position monitor

International Nuclear Information System (INIS)

Kurita, N.; Martin, D.; Ng, C.K.; Smith, S.; Weiland, T.

1995-09-01

The authors use MAFIA to analyze the PEP-II button-type beam position monitor (BPM). Employing proper termination of the BPM into a coaxial cable, the output signal at the BPM is determined. Thus the issues of signal sensitivity and power output can be addressed quantitatively, including all transient effects and wakefields. Besides this first quantitative analysis of a true BPM 3D structure, they find that internal resonant modes are a major-source of high value narrow-band impedances. The effects of these resonances on coupled-bunch instabilities are discussed. An estimate of the power dissipation in the ceramic vacuum seal under high current operation is given

On the average luminosity of electron positron collider and positron-producing energy

International Nuclear Information System (INIS)

Xie Jialin

1985-01-01

In this paper, the average luminosity of linac injected electron positron collider is investigated from the positron-producing energy point of view. When the energy of the linac injector is fixed to be less than the operating energy of the storage ring, it has been found that there exists a positron-producing energy to give optimum average luminosity. Two cases have been studied, one for an ideal storage ring with no single-beam instability and the other for practical storage ring with fast head-tail instability. The result indicates that there is a positron-producing energy corresponding to the minimum injection time, but this does not correspond to the optimum average luminosity for the practical storage rings. For Beijing Electron Positron Collider (BEPC), the positron-producing energy corresponding to the optimum average luminosity is about one tenth of the total injector energy

Next generation of electron-positron colliding beam machines

International Nuclear Information System (INIS)

Richter, B.

1979-03-01

The contribution of electron-positron colliding beam experiments to high-energy physics in the 1970's has been prodigious. From the research done with the two highest-energy e + e - machines of the present generation of these devices, have come such things as the discovery and illumination of the properties of the psi family, charmed particles, a new heavy lepton, non-ambigious evidence for hadronic jets, etc. The rapid pace of new developments in physics from such machines comes about for two reasons. First, the electron-positron annihilation process at present energies is particularly simple and well understood, making the problem of determining the quantum numbers and properties of new particles particularly simple. Second, in electron-positron annihilation all final states are on a relatively equal footing, and small production cross sections are compensated for by a lack of confusing background. For example, the rate of production of charmed particles at the SPEAR storage ring at SLAC and the DORIS storage ring at DESY is 3 or 4 orders of magnitude less than the rate of production at FNAL and the SPS. Yet these particles were first found at the storage rings where the background cross sections are comparable to the signal cross section, and have not yet been observed directly by their hadronic decays at the proton machines where the background cross sections are 4 orders of magnitude larger than the signal cross sections. The machines PEP at SLAC and PETRA at DESY will soon be operating at 35 to 40 GeV cm to explore new regions of energy. Studies of electron-positron annihilation at much higher energies than presently planned have a great deal to teach, not only about particle structure and dynamics, but also about the nature of the weak interaction. Some of the physics which can be done with such machines is discussed with a view toward getting an idea of the minimum required energy for the new generation of colliding beam devices

Commissioning experience from PEP-II HER longitudinal feedback

International Nuclear Information System (INIS)

Prabhakar, S.; Teytelman, D.; Fox, J.; Young, A.; Corredoura, P.; Tighe, R.

1998-06-01

The DSP-based bunch-by-bunch feedback system installed in the PEP-II HER has been used to damp HOM-induced instabilities at beam currents up to 6-5 mA during commissioning. Beam pseudospectra calcualted from feedback system data indicate the presence of coupled bunch modes that oincide with the 0-M-2 cavity HOM. Bunch current and synchronous phase measurements are also extracted from the data. These measurements reveal the impedance seen by the beam at revolution harmonics. The impedance peak at 3*frev indicates incorrect parking of the idle cavities, and explains the observed instability of mode 3. Bunch synchrotron tunes are calculated from lorentzian fits to the data. Bunch-to-bunch time variation due to the cavity transient is shown to be large enough to result in Landau damping of coupled bunch modes

Investigation into electron cloud effects in the International Linear Collider positron damping ring

Energy Technology Data Exchange (ETDEWEB)

Crittenden, J. A.; Conway, J.; Dugan, G. F.; Palmer, M. A.; Rubin, D. L.; Shanks, J.; Sonnad, K. G.; Boon, L.; Harkay, K.; Ishibashi, T.; Furman, M. A.; Guiducci, S.; Pivi, M. T. F.; Wang, L.

2014-03-01

We report modeling results for electron cloud buildup and instability in the International Linear Collider positron damping ring. Updated optics, wiggler magnets, and vacuum chamber designs have recently been developed for the 5 GeV, 3.2-km racetrack layout. An analysis of the synchrotron radiation profile around the ring has been performed, including the effects of diffuse and specular photon scattering on the interior surfaces of the vacuum chamber. The results provide input to the cloud buildup simulations for the various magnetic field regions of the ring. The modeled cloud densities thus obtained are used in the instability threshold calculations. We conclude that the mitigation techniques employed in this model will suffice to allow operation of the damping ring at the design operational specifications

High-power RF window and coupler development for the PEP-II B Factory

International Nuclear Information System (INIS)

Neubauer, M.; Fant, K.; Hodgson, J.; Judkins, J.; Schwarz, H.; Rimmer, R.A.

1995-05-01

We describe the fabrication and testing of the RF windows designed to transmit power to the PEP-II 476 MHz cavities. Design choices to maximize the reliability of the window are discussed. Fabrication technologies for the window are described and finite-element analysis of the assembly process is presented. Conditioning and high-power testing of the window are discussed. Design of the coupler assembly including the integration of the window and other components is reported

Computational tools and lattice design for the PEP-II B-Factory

International Nuclear Information System (INIS)

Cai Yunhai; Irwin, John; Nosochkov, Yuri; Yan, Yiton

1997-01-01

Several accelerator codes were used to design the PEP-II lattices, ranging from matrix-based codes, such as MAD and DIMAD, to symplectic-integrator codes, such as TRACY and DESPOT. In addition to element-by-element tracking, we constructed maps to determine aberration strengths. Furthermore, we have developed a fast and reliable method (nPB tracking) to track particles with a one-turn map. This new technique allows us to evaluate performance of the lattices on the entire tune-plane. Recently, we designed and implemented an object-oriented code in C++ called LEGO which integrates and expands upon TRACY and DESPOT

Progress in measurement and understanding of beam polarization in electron positron storage rings

International Nuclear Information System (INIS)

Barber, D.P.; Bremer, H.D.; Kewisch, J.; Lewin, H.C.; Limberg, T.; Mais, H.; Ripken, G.; Rossmanith, R.; Schmidt, R.

1983-07-01

A report is presented on the status of attempts to obtain and measure spin polarization in electron-positron storage rings. Experimental results are presented and their relationship to predictions of calculations discussed. Examples of methods for decoupling orbital and spin motion and thus improving polarization are discussed. (orig.)

Report of Snowmass 2001 Working Group E2: Electron-Positron Colliders from the Phi to the Z

Energy Technology Data Exchange (ETDEWEB)

Decker, Franz-Josef

2002-08-07

We report on the status and plans of experiments now running or proposed for electron-positron colliders at energies between the {phi} and the Z. The e{sup +}e{sup -} B and charm factories we considered were PEP-II/BABAR, KEKB/Belle, superKEK, SuperBABAR, and CESR-c/CLEO-c. We reviewed the programs at the {phi} factory at Frascati and the proposed PEP-N facility at Stanford Linear Accelerator Center. We studied the prospects for B physics with a dedicated linear collider Z factory, associated with the TESLA high energy linear collider. In all cases, we compared the physics reach of these facilities with that of alternative experiments at hadron colliders or fixed target facilities.

Nuclear physics at PEP: First test and future plans

International Nuclear Information System (INIS)

Van Bibber, K.; Dietrich, F.S.; Melnikoff, S.O.

1986-09-01

A test run of internal target nuclear physics at the PEP storage ring is described. The Time Projection Chamber (TPC-2γ detector) was used to detect the inelastically scattered electron and complete hadronic final state in the interaction of 14.5 GeV electrons with D 2 , Ar and Xe gas targets. The data comprise mostly low-x low-Q 2 events, but some deep inelastic scattering as well. The future possibilities of a dedicated nuclear physics program at PEP are outlined. 15 refs., 25 figs

Proceedings of the Workshop on the SLAC Damping Rings in the 21st Century (DR2000)

CERN Document Server

Nixon, R

1998-01-01

The purpose of the Workshop is to assess the status and needs of the Damping Rings for the era of PEP-II. The goal is to have the Rings perform to produce the specified beam parameters with an insignificant amount of downtime. We want to achieve this status by improving the Rings where necessary, not by increasing the maintenance effort. The things that we can act upon in the immediate future are largely engineering issues to improve the integrated availability of the damping rings.

Proceedings of the Workshop on the SLAC Damping Rings in the 21st Century (DR2000)

International Nuclear Information System (INIS)

Nixon, Robbin

1998-01-01

The purpose of the Workshop is to assess the status and needs of the Damping Rings for the era of PEP-II. The goal is to have the Rings perform to produce the specified beam parameters with an insignificant amount of downtime. We want to achieve this status by improving the Rings where necessary, not by increasing the maintenance effort. The things that we can act upon in the immediate future are largely engineering issues to improve the integrated availability of the damping rings

Properties of the electron cloud in a high-energy positron and electron storage ring

International Nuclear Information System (INIS)

Harkay, K.C.; Rosenberg, R.A.

2003-01-01

Low-energy, background electrons are ubiquitous in high-energy particle accelerators. Under certain conditions, interactions between this electron cloud and the high-energy beam can give rise to numerous effects that can seriously degrade the accelerator performance. These effects range from vacuum degradation to collective beam instabilities and emittance blowup. Although electron-cloud effects were first observed two decades ago in a few proton storage rings, they have in recent years been widely observed and intensely studied in positron and proton rings. Electron-cloud diagnostics developed at the Advanced Photon Source enabled for the first time detailed, direct characterization of the electron-cloud properties in a positron and electron storage ring. From in situ measurements of the electron flux and energy distribution at the vacuum chamber wall, electron-cloud production mechanisms and details of the beam-cloud interaction can be inferred. A significant longitudinal variation of the electron cloud is also observed, due primarily to geometrical details of the vacuum chamber. Such experimental data can be used to provide realistic limits on key input parameters in modeling efforts, leading ultimately to greater confidence in predicting electron-cloud effects in future accelerators.

Bruno Touschek: From Betatrons to Electron-Positron Colliders

Science.gov (United States)

Bernardini, Carlo; Pancheri, Giulia; Pellegrini, Claudio

Bruno Touschek’s life as a physicist spanned the period from World War II to the 1970s. He was a key figure in the developments of electron-positron colliders and storage rings, and made important contributions to theoretical high energy physics. Storage rings, initially developed for high energy physics, are being widely used in many countries as synchrotron radiation sources and are a tool for research in physics, chemistry, biology, environmental sciences and cultural heritage studies. We describe Touschek’s life in Austria, where he was born, in Germany, where he participated in the construction of a betatron during WWII, and in Italy, where he proposed and led to completion the first electron-positron storage ring in 1960, in Frascati. We highlight how his central European culture influenced his lifestyle and work, and his main contributions to physics, such as the discovery of the Touschek effect and beam instabilities in the larger storage ring ADONE.

Dynamic Aperture Improvement of PEP-II Lattices Using Resonance Basis Lie Generators

Energy Technology Data Exchange (ETDEWEB)

Yan, Yiton T

2003-08-11

To simplify the engineering efforts of implementing the PEP-II lattices, many modifications have been made to these lattices since the conceptual design report. During the development and evolution of the lattices, changes in a lattice would often result in a significant reduction in the dynamic aperture. At such times, we often relied on a non-linear analysis using the one-turn resonance basis Lie generator to identify the cause of the degradation. In this paper, we will present such examples to facilitate the usage of map for diagnosing the problems in lattice design.

rf reference line for PEP

International Nuclear Information System (INIS)

Schwarz, H.D.; Weaver, J.N.

1979-03-01

A rf phase reference line in 6 segments around the 2200 meter circumference PEP storage ring is described. Each segment of the reference line is phase stabilized by its own independent feedback system, which uses an amplitude modulated reflection from the end of each line. The modulation is kept small and decoupled from the next segment to avoid crosstalk and significant modulation of the rf drive signal. An error evaluation of the system is made. The technical implementation and prototype performance are described. Prototype tests indicate that the phase error around the ring can be held below 1 degree with this relatively simple system

rf reference line for PEP

Energy Technology Data Exchange (ETDEWEB)

Schwarz, H.D.; Weaver, J.N.

1979-03-01

A rf phase reference line in 6 segments around the 2200 meter circumference PEP storage ring is described. Each segment of the reference line is phase stabilized by its own independent feedback system, which uses an amplitude modulated reflection from the end of each line. The modulation is kept small and decoupled from the next segment to avoid crosstalk and significant modulation of the rf drive signal. An error evaluation of the system is made. The technical implementation and prototype performance are described. Prototype tests indicate that the phase error around the ring can be held below 1 degree with this relatively simple system.

Vacuum system of the high energy ring of an asymmetric B-factory based on PEP

International Nuclear Information System (INIS)

Barletta, W.A.; Calderon, M.O.; Wong, R.; Jenkins, T.M.

1991-01-01

The multi-ampere currents required for high luminosity operation of an asymmetric B factory leads to extremely stressing requirements on a vacuum system suitable for maintaining long beam-gas lifetimes and acceptable background levels in the detector. We present the design for a Cu alloy vacuum chamber and its associated pumping system for the 9 GeV electron storage ring of the proposed B factory based on PEP. The excellent thermal and photo-desorption properties of Cu allows handling the high proton flux in a conventional, single chamber design with distributed ion pumps. The x-ray opacity of the Cu is sufficiently high that no additional lead shielding is necessary to protect the dipoles from the intense synchrotron radiation generated by the beam. The design allows chamber commissioning in <500 hr of operation. 5 refs., 3 figs., 2 tabs

High-power RF window design for the PEP-II B Factory

International Nuclear Information System (INIS)

Neubauer, M.; Hodgson, J.; Ng, C.; Schwarz, H.; Skarpaas, K.; Kroll, N.; Rimmer, R.

1994-06-01

We describe the design of RF windows to transmit up to 500 kW CW to the PEP-II 476 MHz cavities. RF analysis of the windows using high-frequency simulation codes are described. These provide information about the power loss distribution in the ceramic and tim matching properties of the structure. Finite-element analyses of the resulting temperature distribution and thermal stresses are presented. Fabrication methods including a proposed scheme to compensate for thermal expansion s are discussed and hardware tests to validate this approach are described. The effects of surface coatings (intentional and otherwise) and the application of air cooling are considered

Computational tools and lattice design for the PEP-II B-Factory

International Nuclear Information System (INIS)

Cai, Y.; Irwin, J.; Nosochkov, Y.; Yan, Y.

1997-01-01

Several accelerator codes were used to design the PEP-II lattices, ranging from matrix-based codes, such as MAD and DIMAD, to symplectic-integrator codes, such as TRACY and DESPOT. In addition to element-by-element tracking, we constructed maps to determine aberration strengths. Furthermore, we have developed a fast and reliable method (nPB tracking) to track particles with a one-turn map. This new technique allows us to evaluate performance of the lattices on the entire tune-plane. Recently, we designed and implemented an object-oriented code in C++ called LEGO which integrates and expands upon TRACY and DESPOT. copyright 1997 American Institute of Physics

Upgraded cavities for the positron accumulator ring of the APS

International Nuclear Information System (INIS)

Kang, Y.W.; Jiang, X.; Mangra, D.

1997-01-01

Upgraded versions of cavities for the APS positron accumulator ring (PAR) have been built and are being tested. Two cavities are in the PAR: a fundamental 9.8-MHz cavity and a twelfth harmonic 117.3-MHz cavity. Both cavities have been manufactured for higher voltage operation with improved Q-factors, reliability, and tuning capability. Both cavities employ current-controlled ferrite tuners for control of the resonant frequency. The harmonic cavity can be operated in either a pulsed mode or a CW mode. The rf properties of the cavities are presented

Measurement of the hadronic cross section in electron-positron annihilation

International Nuclear Information System (INIS)

Clearwater, S.

1983-11-01

This thesis describes the most precise measurement to date of the ratio R, the hadronic cross section in lowest order electron-positron annihilation to the cross section for muon pair production in lowest order electron-positron annihilation. This experiment is of interest because R is a fundamental parameter that tests in a model independent way the basic assumptions of strong interaction theories. According to the assumptions of one of these theories the value of R is determined simply from the electric charges, spin, and color assignments of the produced quark-pairs. The experiment was carried out with the MAgnetic Calorimeter using collisions of 14.5 GeV electrons and positrons at the 2200m circumference PEP storage ring at SLAC. The MAC detector is one of the best-suited collider detectors for measuring R due to its nearly complete coverage of the full angular range. The data for this experiment were accumulated between February 1982 and April 1983 corresponding to a total event sample of about 40,000 hadronic events. About 5% of the data were taken with 14 GeV beams and the rest of the data were taken with 14.5 GeV beams. A description of particle interactions and experimental considerations is given

Effects of parasitic beam-beam interaction during the injection process at the PEP-II B Factory

International Nuclear Information System (INIS)

Chin, Y.H.

1992-06-01

This paper is concerned with beam-beam effects during the injection process at the proposed asymmetric SLAC/LBL/LLNL B-Factory, PEP-II. It is shown that the parasitic beam-beam interaction can lead to a significant blowup in the vertical size of the injected beam. Simulation results for the horizontal and the vertical injection schemes are presented, and their performances are studied

Design of a high-power test model of the PEP-II rf cavity

International Nuclear Information System (INIS)

Schwarz, H.D.; Bell, R.A.; Hodgson, J.A.

1993-05-01

The design of a normal-conducting high-power test cavity (HPTC) for PEP-II is described. The cavity includes HOM loading waveguides and provisions for testing two alternate input coupling schemes. 3-D electromagnetic field simulations provided input information for the surface power deposition. Finite element codes were utilized for thermal and stress analyses of the cavity to arrive at a suitable mechanical design capable of handling the high power dissipation. The mechanical design approach with emphasis on the cooling channel layout and mechanical stress reduction is described

Positron emission tomography camera

International Nuclear Information System (INIS)

Anon.

1986-01-01

A positron emission tomography camera having a plurality of detector rings positioned side-by-side or offset by one-half of the detector cross section around a patient area to detect radiation therefrom. Each ring contains a plurality of scintillation detectors which are positioned around an inner circumference with a septum ring extending inwardly from the inner circumference along each outer edge of each ring. An additional septum ring is positioned in the middle of each ring of detectors and parallel to the other septa rings, whereby the inward extent of all the septa rings may be reduced by one-half and the number of detectors required in each ring is reduced. The additional septa reduces the costs of the positron camera and improves its performance

Design of traveling wave windows for the PEP-II RF coupling network

International Nuclear Information System (INIS)

Kroll, N.M.; Ng, C.K.; Judkins, J.; Neubauer, M.

1995-05-01

The waveguide windows in the PEP-II RF coupling network have to withstand high power of 500 kW. Traveling wave windows have lower power dissipation than conventional self-matched windows, thus rendering the possibility of less stringent mechanical design. The traveling wave behavior is achieved by providing a reflecting iris on each side of the window, and depending on the configuration of the irises, traveling wave windows are characterized as inductive or capacitive types. A numerical design procedure using MAFIA has been developed for traveling wave windows. The relative advantages of inductive and capacitive windows are discussed. Furthermore, the issues of bandwidth and multipactoring are also addressed

Geotechnical investigations of the PEP site

International Nuclear Information System (INIS)

Gould, R.S.

1976-02-01

The purpose of this paper is to summarize the general nature of the geology and rock and soil formations of the PEP site as they relate to the design and construction of the project; to describe site investigation programs and to catalog the geotechnical information presently available about the site. The recently-completed investigation of subterranean conditions around the PEP ring when coupled with previous surveys gives us a good understanding of what to expect with regard to tunneling, undertaking larger underground excavations and constructing research halls are the interaction areas. It bears out the predictions made in Jacobs and Associates' report of 1973; i.e., that the ring housing construction is classified as soft-ground tunneling and that large underground openings, such as region 10 and the injection junction structures, will require great attention to support. A shield or shields will probably be required. On the positive side, the site affords very good conditions for soft-ground tunneling. Water will be a problem in some areas, but not an unsolvable one. The possibility of encountering lethal or explosive gases, almost always the case in tunneling in California's coastal formations, exists but has not been ascertained. Finally, no reasons to change current cost estimates or schedules have merged from the investigation. 13 refs., 1 fig

Present and future colliding beam facilities at SLAC

International Nuclear Information System (INIS)

Wiedemann, H.

1977-01-01

Present state of the 4.1 GeV electron-positron storage ring SPEAR is described. The most important limitations on performance in SPEAR, such as synchrotron-betatron resonances, higher-order mode losses are outlined. Active bunch lengthener was outstalled in SPEAR to reduce the losses. Experiments on the bunch lengthening observed in SPEAR showed that the lengthening mechanism results from bunch instabilities due to the bunch interaction with the environment. SPEAR performance experience provided with effective prototype for directing the design of PEP-the 18 GeV positron-electron storage ring with designed luminosity of 10 32 cm -2 s -1 . Procurements and construction of PEP components are in full swing. The first beam is expeted to go around in the storage ring by October 1979

PEP computer control system

International Nuclear Information System (INIS)

1979-03-01

This paper describes the design and performance of the computer system that will be used to control and monitor the PEP storage ring. Since the design is essentially complete and much of the system is operational, the system is described as it is expected to 1979. Section 1 of the paper describes the system hardware which includes the computer network, the CAMAC data I/O system, and the operator control consoles. Section 2 describes a collection of routines that provide general services to applications programs. These services include a graphics package, data base and data I/O programs, and a director programm for use in operator communication. Section 3 describes a collection of automatic and semi-automatic control programs, known as SCORE, that contain mathematical models of the ring lattice and are used to determine in real-time stable paths for changing beam configuration and energy and for orbit correction. Section 4 describes a collection of programs, known as CALI, that are used for calibration of ring elements

Electron beam cooling at a magnetic storage ring, TARN II, and an electrostatic storage ring

International Nuclear Information System (INIS)

Tanabe, Tetsumi

2006-01-01

At the High Energy Accelerator Research Organization (KEK), a magnetic storage ring, TARN II, with an electron cooler was operated from 1989 to 1999, while an electrostatic storage ring with a small electron cooler has been operational since 2000. In this paper, the electron cooling at TARN II and the electrostatic storage ring is described. (author)

Higher order mode damping studies on the PEP-II B-Factory RF cavity

International Nuclear Information System (INIS)

Rimmer, R.; Goldberg, D.; Lambertson, G.; Voelker, F.; Ko, K.; Kroll, N.; Pendleton, R.; Schwarz, H.; Adams, F.; De Jong, M.

1992-03-01

We describe studies of the higher-order-mode (HOM) properties of the prototype 476 MHz RF cavity for the proposed PEP-II B-Factory and a waveguide damping scheme to reduce possible HOM-driven coupled-bunch beam instability growth. Numerical studies include modelling of the HOM spectrum using MAFIA and ARGUS, and calculation of the loaded Q's of the damped modes using data from these codes and the Kroll-Yu method. We discuss briefly the experimental investigations of the modes, which will be made in a full-size low-power test cavity, using probes, wire excitation and bead perturbation methods

High-power RF cavity R ampersand D for the PEP-II B Factory

International Nuclear Information System (INIS)

Rimmer, R.; Lambertson, G.; Hodgson, J.

1994-06-01

We describe the development of a high-power test model of the 476 MHz RF cavity for the PEP-II B Factory. This cavity is designed to demonstrate the feasibility of a high-power design with higher-order mode (HOM) damping waveguides and the fabrication technologies involved, and it can also be used to evaluate aperture or loop couplers and various RF windows. Changes to the RF design to reduce peak surface heating are discussed and results of finite-element analyses of temperature and stress are presented. Fabrication methods for the prototype and subsequent production cavities are discussed

Emission tomography with positrons principle, physical performances of a ring detector and quantitative possibilities

International Nuclear Information System (INIS)

Soussaline, F.; Plummer, D.; Todd Pokropek, A.E.; Loc'h, C.; Comar, D.

1979-01-01

Satisfactory qualitative and quantitative data in positron emission tomography requires the use of a well adapted tomographic system. A number of parameters have been identified which can be considered as the critical characteristics for evaluation and intercomparison of such systems. Using these the choice of a single slice ring positron camera could be justified by its physical performance, which is presented and discussed. Series of physical and mathematical simulations allow an appropriate knowledge of such a system, which has been in use for more than a year in a clinical environment. These studies aid to the interpretation of very interesting physiopathologic studies. In principle, a positron tomographic system permits measurement of absolute quantitative concentration values, which are essential for precise metabolic studies. The main sources of error comprising the calibration of the system, the tail effects and the precision for attenuation correction are analysed. When taking in account these errors, a precision of the order of 10% should be obtainable [fr

Status of the MEIC ion collider ring design

International Nuclear Information System (INIS)

Morozov, Vasiliy; Derbenev, Yaroslav; Harwood, Leigh; Hutton, Andrew; Lin, Fanglei; Pilat, Fulvia; Zhang, Yuhong; Cai, Yunhai; Nosochkov, Y. M.; Sullivan, Michael; Wang, M.-H.; Wienands, Uli; Gerity, James; Mann, Thomas; McIntyre, Peter; Pogue, Nathaniel; Sattarov, Akhdiyor

2015-09-01

We present an update on the design of the ion collider ring of the Medium-energy Electron-Ion Collider (MEIC) proposed by Jefferson Lab. The design is based on the use of super-ferric magnets. It provides the necessary momentum range of 8 to 100 GeV/c for protons and ions, matches the electron collider ring design using PEP-II components, fits readily on the JLab site, offers a straightforward path for a future full-energy upgrade by replacing the magnets with higher-field ones in the same tunnel, and is more cost effective than using presently available current-dominated super-conducting magnets. We describe complete ion collider optics including an independently-designed modular detector region.

Status of the MEIC ion collider ring design

International Nuclear Information System (INIS)

Morozov, V. S.; Derbenev, Ya. S.; Harwood, L.; Hutton, A.; Lin, F.; Pilat, F.; Zhang, Y.; Cai, Y.; Nosochkov, Y. M.; Sullivan, M.; Wang, M-H; Wienands, U.; Gerity, J.; Mann, T.; McIntyre, P.; Pogue, N. J.; Satttarov, A.

2015-01-01

We present an update on the design of the ion collider ring of the Medium-energy Electron-Ion Collider (MEIC) proposed by Jefferson Lab. The design is based on the use of super-ferric magnets. It provides the necessary momentum range of 8 to 100 GeV/c for protons and ions, matches the electron collider ring design using PEP-II components, fits readily on the JLab site, offers a straightforward path for a future full-energy upgrade by replacing the magnets with higher-field ones in the same tunnel, and is more cost effective than using presently available current-dominated superconducting magnets. We describe complete ion collider optics including an independently-designed modular detector region.

Commissioning experience with the PEP-II low-level RF system

International Nuclear Information System (INIS)

Corredoura, P.; Allison, S.; Claus, R.; Ross, W.; Sapozhnikov, L.; Schwarz, H.D.; Tighe, R.; Yee, C.; Ziomek, C.

1997-05-01

The low-level RF system for PEP-II is a modular design housed in a VXI environment and supported by EPICS. All signal processing and control is done at baseband using in-phase and quadrature (IQ) techniques. Remotely configurable RF feedback loops are used to control coupled-bunch instabilities driven by the accelerating mode of the RF cavities. A programmable DSP based feedback loop is implemented to control phase variations across the klystron due to the required adjustment of the cathode voltage to limit cathode power dissipation. The DSP loop also adaptively cancels modulations caused by klystron power supply ripple at selected power line harmonics between 60 Hz and 10 kHz. The system contains a built-in baseband network analyzer which allows remote measurement of the RF feedback loop transfer functions and automated configuration of these loops. This paper presents observations and measured data from the system

Peptidase-3 (Pep-3), dipeptidase variant in the rat homologous to mouse pep-3 (Dip-1) and human PEP-c.

Science.gov (United States)

Womack, J E; Cramer, D V

1980-10-01

Starch gel electrophoresis and histochemical staining with L-leucyl-L-tyrosine have revealed genetic variation for dipeptidase in Rattus norvegicus. The tissue distribution, substrate specificity, and heterozygous expression as a monmeric protein suggest homology of the variant peptidase to human PEP-C and mouse Pep-3 (Dip-1). We propose Peptidase-3 (Pep-3) as a name for this autosomal locus in the rat. The allele responsible for slower (less anodal) electrophoretic migration is designated Pep-3a and is characteristic of strain ACI/Pit. A faster (more anodal) electrophoretic mobility is the product of the Pep-3b allele in strain F344/Pit. Twenty-five additional inbred strains carry Pep-3a and 16 others carry Pep-3b. Wild rats trapped in Pittsburgh were polymorphic for this locus. Alleles at Pep-3 segregated independently of c (linkage group I), a (linkage group IV), RT2 and Es-1 (linkage group V), h (linkage group VI), and RTI (linkage group VIII).

APS [Advanced Photon Source] interests in PEP

International Nuclear Information System (INIS)

Moncton, D.E.; Shenoy, G.K.; Mills, D.M.

1987-11-01

As one of the very few high-energy electron storage rings in the world, potentially available for synchrotron radiation studies, PEP represents an opportunity to accomplish certain preconstruction R and D tasks relevant to the successful construction and operation of dedicated user facilities such as the Advanced Photon Source (APS) at Argonne. Three topical areas are discussed: Accelerator R and D, Insertion Devices (ID) R and D, and Beam Line Instrumentation R and D

Measurements of a Fast Vertical Instability in the PEP-II HER

International Nuclear Information System (INIS)

Matter, Regina S.

2000-01-01

The HER beam current was limited to tens of mA by a strong vertical coupled bunch instability during PEP-II commissioning in July '98. In the absence of transverse feedback, vertical oscillations were seen to be unstable at currents as low as 5 mA. The instability has been observed by using the HER longitudinal feedback electronics to digitize and store the vertical beam signal used for transverse feedback. This note presents measurements of modal growth and damping rates at two different vacuum pressures for 291 bunch uniform fills as well as 100 and 150 bunch train measurements. In some cases the unstable modes maintain a constant residual amplitude when feedback is on, and exhibit nonlinear behavior when feedback is switched off. Knowledge of the shape, speed and spectral location of the modal transients should help in diagnosing the cause of instability

Measuring, calculating and estimating PEP's parasitic mode loss parameters

International Nuclear Information System (INIS)

Weaver, J.N.

1981-01-01

This note discusses various ways the parasitic mode losses from a bunched beam to a vacuum chamber can be measured, calculated or estimated. A listing of the parameter, k, for the various PEP ring components is included. A number of formulas for calculating multiple and single pass losses are discussed and evaluated for several cases. 25 refs., 1 fig., 1 tab

Preliminary design considerations for the stage 1 PEP lattice

International Nuclear Information System (INIS)

Helm, R.H.; Lee, M.J.

1974-07-01

A general description of the proposed PEP e + e - storage ring is discussed in the paper. We discuss the lattice and its operating characteristics in more detail, show how the design luminosity operative regions may be met and outline the limits of the operative regions of the beam parameters in several modes of operation. 18 refs., 16 figs., 1 tab

Study for ILC Damping Ring at KEKB

Energy Technology Data Exchange (ETDEWEB)

Flanagan, J.W.; Fukuma, H.; Kanazawa, K.I.; Koiso, H.; Masuzawa, M.; Ohmi, Kazuhito; Ohnishi, Y.; Oide, Katsunobu; Suetsugu, Y.; Tobiyama, M.; /KEK, Tsukuba; Pivi, M.; /SLAC

2011-11-04

ILC damping ring consists of very low emittance electron and positron storage rings. It is necessary for ILC damping ring to study electron cloud effects in such low emittance positron ring. We propose a low emittance operation of KEKB to study the effects.

Shielding required for radiation produced by 15 GeV stored electrons

International Nuclear Information System (INIS)

Jenkins, T.M.; McCaslin, J.B.; Thomas, R.H.

1974-01-01

The first phase of PEP will consist of a 15 GeV electron and positron storage ring. This note examines the shielding required by such a facility. Shielding of neutrons and muons produced by 200 GeV protons in the second phase of PEP has been discussed in previous notes. 9 refs., 9 figs., 5 tabs

Particle searches in e+e- experiments at PEP and PETRA

International Nuclear Information System (INIS)

Lau, K.H.

1982-10-01

This talk reviews recent results in new particle searches performed by experiments at the high energy e + e - storage rings PEP and PETRA. It concentrates on recent searches for: hadrons with a new quark flavor, spin-1/2 charged heavy leptons, spin-0 charged leptons, spin-0 point-like scalars or pseudoscalars, and neutral heavy leptons

Development of a 144-channel Hybrid Avalanche Photo-Detector for Belle II ring-imaging Cherenkov counter with an aerogel radiator

Energy Technology Data Exchange (ETDEWEB)

Nishida, S., E-mail: shohei.nishida@kek.jp [High Energy Accelerator Research Organization (KEK), Tsukuba (Japan); Adachi, I. [High Energy Accelerator Research Organization (KEK), Tsukuba (Japan); Hamada, N. [Toho University, Funabashi (Japan); Hara, K. [High Energy Accelerator Research Organization (KEK), Tsukuba (Japan); Iijima, T. [Nagoya University, Nagoya (Japan); Iwata, S.; Kakuno, H. [Tokyo Metropolitan University, Hachioji (Japan); Kawai, H. [Chiba University, Chiba (Japan); Korpar, S.; Krizan, P. [Jozef Stefan Institute, Ljubljana (Slovenia); Ogawa, S. [Toho University, Funabashi (Japan); Pestotnik, R.; Ŝantelj, L.; Seljak, A. [Jozef Stefan Institute, Ljubljana (Slovenia); Sumiyoshi, T. [Tokyo Metropolitan University, Hachioji (Japan); Tabata, M. [Chiba University, Chiba (Japan); Tahirovic, E. [Jozef Stefan Institute, Ljubljana (Slovenia); Yoshida, K. [Tokyo Metropolitan University, Hachioji (Japan); Yusa, Y. [Niigata University, Niigata (Japan)

2015-07-01

The Belle II detector, a follow up of the very successful Belle experiment, is under construction at the SuperKEKB electron–positron collider at KEK in Japan. For the PID system in the forward region of the spectrometer, a proximity-focusing ring-imaging Cherenkov counter with an aerogel radiator is being developed. For the position sensitive photon sensor, a 144-channel Hybrid Avalanche Photo-Detector has been developed with Hamamatsu Photonics K.K. In this report, we describe the specification of the Hybrid Avalanche Photo-Detector and the status of the mass production.

Searches for new particles at PEP

International Nuclear Information System (INIS)

Jonker, M.J.

1986-05-01

The status of searches for new particles at the PEP storage ring is reviewed. The result of the excited electron search by MARKII is presented and a limit on the coupling strength of the e*eγ vertex is given. The search for single photons in the ASP and MAC detectors is reported and the results are used to set limits on the number of light neutrino species and, in the context of supersymmetry (SUSY) theories, are interpreted as setting simultaneous limits on the masses of the selectron and photino

New results on flavor production at PEP

International Nuclear Information System (INIS)

Barbaro-Galtieri, A.

1984-05-01

This report includes results from five PEP detectors: DELCO, HRS, MAC, MARK II and TPC. All, except the TPC, are presently taking data at PEP. The TPC is being upgraded: a new superconducting coil is being installed and other improvements are being implemented. The results discussed here are either new or improved since the Cornell Conference. New results on Particle Searches and a limit on neutrino generations are discussed. New data are included on weak couplings of c and b quarks. Various new results on hadron production are reported. All data were obtained in e +- collisions with total energy √s=29 GeV. 54 references

SPEAR II performance

International Nuclear Information System (INIS)

Paterson, J.M.

1975-01-01

The single beam and colliding beam performance of the SLAC electron-positron storage ring SPEAR II is described. The sevenfold increase in harmonic number in SPEAR II in comparison to SPEAR I has made significant changes in single beam behavior. Strong synchrobetatron resonances and a new transverse instability are observed, and our first studies of these phenomena are described. Measurements on current dependent bunch lengthening are presented. (auth)

Design and performance of PEP dc-power systems

International Nuclear Information System (INIS)

Jackson, T.

1981-03-01

The PEP Magnet Power Supply System represents a significant departure from previous technology with the goal of improved performance at lower cost. In nineteen of the magnet families around the ring, Chopper power supplies are used. The many choppers are powered from two 2 MW dc supplies, and control the average power to the various magnet loads by pulse-width modulation at a 2 kilohertz repetition rate. Each chopper utilizes SCR's for switching, and stores sufficient capacitive energy for turn-off on command. Most of the energy is recirculated, resulting in high-efficiency. The two kilohertz chopping rate allows a one kilohertz unity-gain bandwidth in the current-regulator loop, and this wide bandwidth, coupled with low drift components in the error-detection system, provides a high-performance system. The PEP system has also shown that the chopper system is economical compared to standard multi-pulse controlled-rectifier

Solvated Positron Chemistry. II

DEFF Research Database (Denmark)

Mogensen, O. E.

1979-01-01

The reaction of the hydrated positron, eaq+ with Cl−, Br−, and I− ions in aqueous solutions was studied by means of positron The measured angular correlation curves for [Cl−, e+], [Br−, e+, and [I−, e+] bound states were in good agreement with th Because of this agreement and the fact...... that the calculated positron wavefunctions penetrate far outside the X− ions in the [X−, e+] sta propose that a bubble is formed around the [X−, e+] state, similar to the Ps bubble found in nearly all liquids. F−ions did not react w Preliminary results showed that CN− ions react with eaq+ while OH−ions are non...... in the Cl− case) at higher concentrations. This saturation and the high-concentration effects-in the angular correlation results were interpreted as caused by rather complicated spur effects, wh It is proposed that spur electrons may pick off the positron from the [X−, e+ states with an efficiency which...

DIRC, the internally reflecting ring imaging Cherenkov detector for BABAR

International Nuclear Information System (INIS)

Adam, I.; Aston, D.

1997-11-01

The DIRC is a new type of Cherenkov imaging device that will be used for the first time in the BABAR detector at the asymmetric B-factory, PEP-II. It is based on total internal reflection and uses long, rectangular bars made from synthetic fused silica as Cherenkov radiator and light guide. The principles of the DIRC ring imaging Cherenkov technique are explained and results from the prototype program are presented. Its choice for the BABAR detector particle identification system is motivated, followed by a discussion of the quartz radiator properties and the detector design

Review of e+e- physics at PEP - 1982

International Nuclear Information System (INIS)

Hollebeek, R.

1982-10-01

Results obtained at PEP by the MARK II, MAC and DELCO collaborations in the past year are reviewed. They include QED tests, measurements of tau lepton properties, charm and bottom fragmentation functions, scaling violations, energy correlations and the total hadronic cross section

Normal form analysis of linear beam dynamics in a coupled storage ring

International Nuclear Information System (INIS)

Wolski, Andrzej; Woodley, Mark D.

2004-01-01

The techniques of normal form analysis, well known in the literature, can be used to provide a straightforward characterization of linear betatron dynamics in a coupled lattice. Here, we consider both the beam distribution and the betatron oscillations in a storage ring. We find that the beta functions for uncoupled motion generalize in a simple way to the coupled case. Defined in the way that we propose, the beta functions remain well behaved (positive and finite) under all circumstances, and have essentially the same physical significance for the beam size and betatron oscillation amplitude as in the uncoupled case. Application of this analysis to the online modeling of the PEP-II rings is also discussed

Positron emission tomography camera

International Nuclear Information System (INIS)

Anon.

1987-01-01

A positron emission tomography camera having a plurality of detector rings positioned side-by-side or offset by one-half of the detector cross section around a patient area to detect radiation therefrom. Each detector ring or offset ring includes a plurality of photomultiplier tubes and a plurality of scintillation crystals are positioned relative to the photomultiplier tubes whereby each tube is responsive to more than one crystal. Each alternate crystal in the ring is offset by one-half or less of the thickness of the crystal such that the staggered crystals are seen by more than one photomultiplier tube. This sharing of crystals and photomultiplier tubes allows identification of the staggered crystal and the use of smaller detectors shared by larger photomultiplier tubes thereby requiring less photomultiplier tubes, creating more scanning slices, providing better data sampling, and reducing the cost of the camera. The offset detector ring geometry reduces the costs of the positron camera and improves its performance

Hall-effect electric fields in semiconducting rings. II

International Nuclear Information System (INIS)

Gorodzha, L.V.; Emets, Yu.P.; Stril'ko, S.I.

1987-01-01

A calculation is presented for the current density distribution in a semiconducting ring with two electrodes symmetrically located on the outer boundary (system II, Fig. 1). The difference between this electrode position and that on the ring considered previously (system I) leads to substantial changes in the shape of the electric field

Peptide drug stability: The anti-inflammatory drugs Pep19-2.5 and Pep19-4LF in cream formulation.

Science.gov (United States)

Kuhlmann, Nicole; Heinbockel, Lena; Correa, Wilmar; Gutsmann, Thomas; Goldmann, Torsten; Englisch, Uwe; Brandenburg, Klaus

2018-03-30

In previous years, we developed anti-infective drugs based on antimicrobial peptides (AMPs), which have been shown to effectively block severe infections and inflammation in vitro as well as in vivo. Besides systemic application, the occurrence of severe local infections necessitates a topical application for example in the case of severe skin and soft tissue infections (SSTI). Recent investigations show that the synthetic anti-lipopolysaccharide peptide (SALP) Pep19-2.5 (Aspidasept® I) and a variant called Pep19-4LF (Aspidasept® II) are able to supress inflammation reactions also in keratinocytes, Langerhans cells, and dendritic cells from the skin. For topical application, a possible formulation represents the drug dispersed into a pharmaceutical cream (DAC base cream). Here, we present investigations on the stability of the peptides using this formulation in dependence on time, which includes the evaluation of the extraction procedure, the quantitative analysis of the peptides after extraction, its sensitivity to protease degradation and its ability to maintain activity against LPS-induced inflammation in vitro. We have developed an extraction procedure for the peptides with an optimum yield and showed that Pep19-2.5 is present as a dimer after extraction from the cream, whereas Pep19-4LF retains its monomeric form. Both peptides show no degradation by chymotrypsin after extraction for at least 1 h, which is indicative for an attachment of constituents of the base cream, inhibiting the cutting into peptidic part structures. The extracted peptides and in particular the dimeric Pep19-2.5 are still able to inhibit the LPS-induced inflammation reaction in human mononuclear cells. Copyright © 2018 Elsevier B.V. All rights reserved.

Operation of a five-pole superconducting wiggler in the DCI positron ring and design of the beamline

International Nuclear Information System (INIS)

Bazin, C.; Dubuisson, J.M.; Labeque, A.; Level, M.P.; Raoux, D.; Sommer, M.; Zyngier, H.; Chomillier, J.; Frouin, J.; Garreau, Y.; Loupias, G.; Tarbes, J.

1989-01-01

A five-pole superconducting wiggler has been installed in the DCI positron ring and operated without disturbing the machine characteristics at full energy (1.85 GeV) and maximum current (300 mA). Three beamlines have been built which feed six beam ports. The first two-crystal monochromator to be used for Compton scattering has been commissioned although the sagittal focusing has not yet been tested

Panel discussion on laboratory accelerator programs: present and future

International Nuclear Information System (INIS)

Richter, B.

1986-09-01

The present SLAC accelerator program is summarized briefly, and the future of electron-positron colliders is discussed. Present activities discussed include the PEP storage ring, the SPEAR storage ring, the Linear Accelerator, and the SLAC Linear Collider (SLC) project. Future prospects include a larger scale linear collider. The stability requirements on acceleration are briefly discussed

Development of a movable plunger tuner for the high-power RF cavity for the PEP-II B-factory

International Nuclear Information System (INIS)

Schwarz, H.D.; Fant, K.; Judkins, J.G.

1997-05-01

A 10 cm diameter by 5 cm travel plunger tuner was developed for the PEP-II RF copper cavity system. The single cell cavity including the tuner is designed to operate up to 150 kW of dissipated RF power are specially placed 8.5 cm away from the inside wall of the cavity to avoid fundamental and higher order mode resonances. The spring fingers are made of dispersion-strengthened copper to accommodate relatively high heating. The design, alignment, testing and performance of the tuner is described

Characteristics of NaI detector in positron imaging device HEADTOME employing circular ring array

International Nuclear Information System (INIS)

Miura, Shuichi; Kanno, Iwao; Aizawa, Yasuo; Murakami, Matsutaro; Uemura, Kazuo

1984-01-01

In positron emission computed tomographs employing circular ring arrays of detectors, the performance of the imaging device has been specified ultimately by the characteristics of the detector. The responses of NaI detector were studied when detecting positron annihilation photon (511 keV). The study was mainly by using the NaI detector used in hybrid emission computed tomography (CT) ''HEADTOME'' we had developed. A series of measurements were carried out positioning two detectors with 40 cm distance and scanning 22 Na point source in water. Both detectors was inclined from 0 0 through 30 0 to change incident angle of positron annihilation toward crystal face. Energy window was set from 100 to 700 keV. The results were presented as follows; 1 Shortening the crystal length from 7 to 5 cm made sensitivity decrease about 10% and resolution deteriorate about 1 mm (FWHM). 2 As the results of varying the width of the crystal, 20 mm width was optimal at any incident angle. 3 The lead septum between the detectors was the thickness of 4 mm enough to reject multiple detector interactions (crosstalk). 4 Beam mask which was made of lead in order to improve spatial resolution and placed on crystal face worked effectively for incident angles from 0 0 to 15 0 but degraded uniformity of spatial resolution from 0 0 to through 30 0 . (author)

Radiation and electrical safety systems for PEP

International Nuclear Information System (INIS)

Smith, H.; Constant, T.; Crook, K.; Fitch, J.; Taylor, T.

1981-02-01

At SLAC, the Personnel Protection System (PPS) protects people from radiation hazards. For PEP, the system has been expanded to include protection against electrical and RF hazards. This paper describes the overall system design, giving particular attention to the novel features not found in similar systems in other areas of SLAC. These include the Restricted Access Mode to allow limited occupancy in the ring while high voltage or RF may be present, the automatic badge reader system for improving the efficiency of entry logging and control, and the solid state lighting control system for switching large lighting loads with minimum electro-magetic interference

Future Synchrotron Light Sources Based on Ultimate Storage Rings

International Nuclear Information System (INIS)

Cai, Yunhai

2012-01-01

have made significant progress with the design of PEP-X, a USR that would inhabit the decommissioned PEP-II tunnel at SLAC. The enlargement of the dynamic aperture is largely a result of the cancellations of the 4th-order resonances in the 3rd-order achromats and the effective use of lattice optimization programs. In this paper, we will show those cancellations of the 4th-order resonances using an analytical approach based on the exponential Lie operators and the Poisson brackets. Wherever possible, our analytical results will be compared with their numerical counterparts. Using the derived formulae, we will construct 4th-order geometric achromats and use them as modules for the lattice of the PEP-X USR, noting that only geometric terms are canceled to the 4th order.

Future Synchrotron Light Sources Based on Ultimate Storage Rings

Energy Technology Data Exchange (ETDEWEB)

Cai, Yunhai; /SLAC

2012-04-09

achromatic cell, we have made significant progress with the design of PEP-X, a USR that would inhabit the decommissioned PEP-II tunnel at SLAC. The enlargement of the dynamic aperture is largely a result of the cancellations of the 4th-order resonances in the 3rd-order achromats and the effective use of lattice optimization programs. In this paper, we will show those cancellations of the 4th-order resonances using an analytical approach based on the exponential Lie operators and the Poisson brackets. Wherever possible, our analytical results will be compared with their numerical counterparts. Using the derived formulae, we will construct 4th-order geometric achromats and use them as modules for the lattice of the PEP-X USR, noting that only geometric terms are canceled to the 4th order.

Operation of the PEP transverse beam feedback

International Nuclear Information System (INIS)

Olson, C.W.; Paterson, J.M.; Pellegrin, J.L.; Rees, J.R.

1981-02-01

The PEP Storage Ring has been equipped with a wide band beam feedback system capable of damping the vertical and horizontal motion of six bunches. The oscillation detection is done at a symmetry point on the Storage Ring and feedback is applied at the same location one orbital period later. The signal is synchronously gated and the system appears as twelve independent feedback loops, operating on the two coordinates of each of the six bunches. Two beam deflection electrodes are driven each by a low-Q push-pull amplifier which is tuned at the 72nd harmonic of the revolution frequency and suppressed-carrier modulation is generated by a sequence of the detected bunch oscillations. The design parameters are reviewed as well as the salient features of the hardware, and the impact of this system on the machine operation is evaluated in the light of experimental results

Measurement of Electron Clouds in Large Accelerators by Microwave Dispersion

Energy Technology Data Exchange (ETDEWEB)

De Santis, S.; Byrd, J.M.; /LBL, Berkeley; Caspers, F.; /CERN; Krasnykh, A.; /SLAC; Kroyer, T.; /CERN; Pivi, M.T.F.; /SLAC; Sonnad, K.G.; /LBL, Berkeley

2008-03-19

Clouds of low energy electrons in the vacuum beam pipes of accelerators of positively charged particle beams present a serious limitation for operation at high currents. Furthermore, it is difficult to probe their density over substantial lengths of the beam pipe. We have developed a novel technique to directly measure the electron cloud density via the phase shift induced in a TE wave transmitted over a section of the accelerator and used it to measure the average electron cloud density over a 50 m section in the positron ring of the PEP-II collider at the Stanford Linear Accelerator Center.

PEP Laser Surveying System

International Nuclear Information System (INIS)

Lauritzen, T.; Sah, R.C.

1979-03-01

A Laser Surveying System has been developed to survey the beam elements of the PEP storage ring. This system provides automatic data acquisition and analysis in order to increase survey speed and to minimize operator error. Two special instruments, the Automatic Readout Micrometer and the Small Automatic Micrometer, have been built for measuring the locations of fiducial points on beam elements with respect to the light beam from a laser. These instruments automatically encode offset distances and read them into the memory of an on-line computer. Distances along the beam line are automatically encoded with a third instrument, the Automatic Readout Tape Unit. When measurements of several beam elements have been taken, the on-line computer analyzes the measured data, compared them with desired parameters, and calculates the required adjustments to beam element support stands

Beam loading in high-energy storage rings

International Nuclear Information System (INIS)

Wilson, P.B.

1974-06-01

The analysis of beam loading in the RF systems of high-energy storage rings (for example, the PEP e/sup /minus//e/sup +/ ring) is complicated by the fact that the time, T/sub b/, between the passage of successive bunches is comparable to the cavity filling time, T/sub b/. In this paper, beam loading expressions are first summarized for the usual case in which T/sub b/ /much lt/ T/sub f/. The theory of phase oscillations in the heavily-beam-loaded case is considered, and the dependence of the synchrotron frequency and damping constant for the oscillations on beam current and cavity tuning is calculated. Expressions for beam loading are then derived which are valid for any value of the ratio T/sub b//T/sub f/. It is shown that, for the proposed PEP e/sup /minus//e/sup +/ ring parameters, the klystron power required is increased by about 3% over that calculated using the standard beam loading expressions. Finally, the analysis is extended to take into account the additional losses associated with the excitation of higher-order cavity modes. A rough numerical estimate is made of the loss enhancement to be expected for PEP RF system. It is concluded that this loss enhancement might be substantial unless appropriate measures are taken in the design and tuning of the accelerating structure

A Design Report of the Baseline for PEP-X: an Ultra-Low Emittance Storage Ring

Energy Technology Data Exchange (ETDEWEB)

Bane, Karl; Bertsche, Kirk; Cai, Yunhai; Chao, Alex; Corbett, Willian; Fox, John; Hettel, Robert; Huang, Xiaobiao; Huang, Zhirong; Ng, Cho-Kuen; Nosochkov, Yuri; Novokhatski, Sasha; Radedeau, Thomas; Raubenheimer, Tor; Rivetta, Claudio; Safranek, James; Seeman, John; Stohr, Joachim; Stupakov, Gennady; Wang, Lanfa; Wang, Min-Huey; /SLAC

2010-06-02

Over the past year, we have worked out a baseline design for PEP-X, as an ultra-low emittance storage ring that could reside in the existing 2.2-km PEPII tunnel. The design features a hybrid lattice with double bend achromat (DBA) cells in two arcs and theoretical minimum emittance (TME) cells in the remaining four arcs. Damping wigglers are used to reduce the horizontal emittance to 86 pm-rad at zero current for a 4.5 GeV electron beam. At a design current of 1.5 A, the horizontal emittance increases, due to intrabeam scattering, to 164 pm-rad when the vertical emittance is maintained at a diffraction limited 8 pm-rad. The baseline design will produce photon beams achieving a brightness of 10{sup 22} (ph/s/mm{sup 2}/mrad{sup 2}/0.1% BW) at 10 keV in a 3.5-m conventional planar undulator. Our study shows that an optimized lattice has adequate dynamic aperture, while accommodating a conventional off-axis injection system. In this report, we present the results of study, including the lattice properties, nonlinear dynamics, intra-beam scattering and Touschek lifetime, RF system, and collective instabilities. Finally, we discuss the possibility of partial lasing at soft X-ray wavelengths using a long undulator in a straight section.

RF feedback simulation for the PEP-II B Factory

International Nuclear Information System (INIS)

Tighe, R.

1994-06-01

A model, of the beam and RF system for PEP-11 has been developed to allow both time-domain simulation and frequency-domain analysis of the complete system. The model includes the full set of feedback loops and nonlinear elements such as the beam and klystron. The model may be used to predict beam and feedback stability in the presence of nonlinearities through time-domain simulation as well as system frequency response about a given operating point

PEP surveying procedures and equipment

International Nuclear Information System (INIS)

Linker, F.

1982-06-01

The PEP Survey and Alignment System, which employs both laser-based and optical survey methods, is described. The laser is operated in conjunction with the Tektronix 4051 computer and surveying instruments such as ARM and SAM, system which is designed to automate data input, reduction, and production of alignment instructions. The laser system is used when surveying ring quadrupoles, main bend magnets, sextupoles, and is optional when surveying RF cavities and insertion quadrupoles. Optical methods usually require that data be manually entered into the computer for alignment, but in some cases, an element can be aligned using nominal values of fiducial locations without use of the computer. Optical surveying is used in the alignment of NIT and SIT, low field bend magnets, wigglers, RF cavities, and insertion quadrupoles

Changing the PEP-II Center-of-Mass Energy Down to 10 GeV and up to 11 GeV

International Nuclear Information System (INIS)

Sullivan, M.

2009-01-01

PEP-II, the SLAC, LBNL, LLNL B-Factory was designed and optimized to run at the Upsilon 4S resonance (10.580 GeV with an 8.973 GeV e- beam and a 3.119 GeV e+ beam). The interaction region (IR) used permanent magnet dipoles to bring the beams into a head-on collision. The first focusing element for both beams was also a permanent magnet. The IR geometry, masking, beam orbits and beam pipe apertures were designed for 4S running. Even though PEP-II was optimized for the 4S, we successfully changed the center-of-mass energy (E cm ) down to the Upsilon 2S resonance and completed an E cm scan from the 4S resonance up to 11.2 GeV. The luminosity throughout most of these changes remained near 1 x 10 34 cm -2 s -1 . The E cm was changed by moving the energy of the high-energy beam (HEB). The beam energy differed by more than 20% which produced significantly different running conditions for the RF system. The energy loss per turn changed 2.5 times over this range. We describe how the beam energy was changed and discuss some of the consequences for the beam orbit in the interaction region. We also describe some of the RF issues that arose and how we solved them as the high-current HEB energy changed

Coaxial wire impedance measurements of BPM buttons for the PEP-II B- factory

International Nuclear Information System (INIS)

Corlett, J.N.

1995-09-01

The coaxial wire impedance measurement uses a conducting rod placed along the beam axis in the vacuum chamber, forming the center conductor in a coaxial line system. Tapers at either end of this section allow for smooth impedance transformation from the 50Ω lines used in common microwave measurement equipment, to the characteristic impedance of the vacuum chamber and center conductor, typically around 200Ω. RF and microwave absorptive material placed in the ends of the vacuum chamber and in the impedance matching tapers minimizes reflections which cause trapped modes within the apparatus, allowing measurements to be made above the traveling-wave cut-off frequency of the vacuum vessel (typically 2.5 - 3.0 GHz for PEP-II). A smooth vessel of the same cross-section as that containing the device under test is used in a reference measurement Resonances within the apparatus are difficult to avoid completely and require careful placing of absorptive material, manufacture of test and reference chambers, and assembly of apparatus

Performance evaluation of PEP

International Nuclear Information System (INIS)

Zisman, M.S.

1987-10-01

An investigation of collective effects has been undertaken to assess the possibilities for using the low emittance operating mode of the PEP storage ring as a dedicated source of synchrotron radiation. Beam current limitations associated with longitudinal and transverse instabilities, and the expected emittance growth due to intrabeam scattering have been studied as a function of beam energy. Calculations of the beam lifetime due to Touschek and gas scattering are presented, and the growth times of coupled-bunch instabilities are estimated. In general, the results are encouraging, and no fundamental problems have been uncovered. It appears that beam currents up to about 10 mA per bunch should be achievable, and that the emittance growth is not a severe problem at an energy of about 8 GeV. A feedback system to deal with coupled-bunch instabilities is likely to be required. 7 refs., 13 figs

The Danish PEP Registry

DEFF Research Database (Denmark)

Lunding, Suzanne; Katzenstein, Terese L; Kronborg, Gitte

2016-01-01

BACKGROUND: The risk of occupational exposures to blood cannot be eliminated completely and access to post-exposure prophylaxis (PEP) to prevent HIV transmission is important. However, PEP administration has been associated with frequent adverse effects, low compliance and difficulties to ensure ...

Search for scalar electrons at PEP

International Nuclear Information System (INIS)

Wilson, R.J.

1983-08-01

Experimental results from e + e - reactions at the Positron Electron Project (PEP) using the High Resolution Spectrometer (HRS) are presented. Events with two electrons, and no other charged particles, in the final state are studied. Limits are given for the production of scalar-electrons predicted by models based on supersymmetry. In particular the pair production of such particles through s-channel single photon annihilation and t-channel inelastic scattering is considered. The data are well described by quantum electrodynamics (QED) but we observe one event which is also consistent with a supersymmetric model. Using this single event we find that the mass, M/sub se/, of these scalar-electrons es excluded, to 95% CL, in the range 1.8 less than or equal to M/sub se/ less than or equal to 14.2 GeV/c 2 . A description of the HRS detector is given with particular emphasis on the electronic trigger system

TOP counter for particle identification at the Belle II experiment

Energy Technology Data Exchange (ETDEWEB)

Inami, Kenji

2014-12-01

Ring imaging Cherenkov counter, named TOP counter, utilizing precise photon detection timing has been developed as a particle identification detector for the Belle II experiment. The real size prototype has been produced and tested with 2 GeV positrons at Spring-8 LEPS beam line. The quartz radiator production and assembling with microchannel plate photomultipliers was successfully carried out. The beam test data shows good agreement with full Monte-Carlo simulation results in the ring image and the distribution of number of detected photons and timing information. - Highlights: • TOP counter was developed as a particle identification detector for the Belle II experiment. • The real size prototype was produced and tested with 2 GeV positrons. • The quartz radiator production and assembling with MCP-PMT was successfully carried out. • The beam test data shows good agreement with full Monte-Carlo simulation results.

Electron-positron interactions

International Nuclear Information System (INIS)

Wiik, B.; Wolf, G.

1979-01-01

This book is an introduction into the physics of electron-positron interactions. After a description of electron-positron storage rings pure electromagnetic e + e - interactions, and the total cross section are considered. Then low energy processes, the production of the J/psi and psi' particles including their radiative decay as well as the search for other narrow vector states are described. Then after the quark model interpretation of J/psi and psi' charmed mesons, the heavy lepton t, and the upsilon resonances are described. Thereafter inclusive hadron production and jet formation is discussed. Finally the next generation of e + e - colliding rings is described, and the first results from PETRA are presented. This book is suited for all physicists, who want to get a general review about e + e - physics. (HSI) 891 HSI/HSI 892 RKD

Simulation of the electron cloud density in BEPC II

International Nuclear Information System (INIS)

Liu Yudong; Guo Zhiyuan; Wang Jiuqing

2004-01-01

Electron Cloud Instability (ECI) may take place in positron storage ring when the machine is operated with multi-bunch positron beam. According to the actual shape of the vacuum chamber in the BEPC II, a program has been developed. With the code, authors can calculate the electron density in the chamber with different length of antechamber and the different secondary electron yield respectively. By the simulation, the possibility to put clearing electrodes in the chamber to reduce the electron density in the central region of the chamber is investigated. The simulation provides meaningful and important results for the BEPC II project and electron cloud instability research

Polarized particles in storage rings

International Nuclear Information System (INIS)

Derbenev, Ya.S.; Kondratenko, A.M.; Serednyakov, S.I.; Skrinskij, A.N.; Tumajkin, G.M.; Shatunov, Yu.M.

1977-01-01

Experiments with polarized beams on the VEPP-2M and SPEAK storage rings are described. Possible methods of producing polarized particle beams in storage rings as well as method of polarization monitoring are counted. Considered are the processes of radiation polarization of electrons and positrons. It is shown, that to preserve radiation polarization the introduction of regions with a strong sign-variable magnetic field is recommended. Methods of polarization measurement are counted. It is suggested for high energies to use dependence of synchrotron radiation power on transverse polarization of electrons and positrons. Examples of using polarizability of colliding beams in storage rings are presented

Trigger drift chamber for the upgraded mark II detector at PEP

Science.gov (United States)

Ford, W. T.; Smith, J. G.; Wagner, S. R.; Weber, P.; White, S. L.; Alvarez, M.; Calviño, F.; Fernandez, E.

1987-04-01

A small cylindrical track detector was built as an array of single-wire drift cells with aluminized mylar cathode tubes. Point measurement resolution of ˜ 90 μm was achieved with a drift gas of 50% argon-50% ethane at atmospheric pressure. The chamber construction, electronics, and calibration are discussed. Performance results from PEP colliding-beam data are presented.

Quality control procedures in positron tomography

International Nuclear Information System (INIS)

Spinks, T.; Jones, T.; Heather, J.; Gilardi, M.

1989-01-01

The derivation of physiological parameters in positron tomography relies on accurate calibration of the tomograph. Normally, the calibration relates image pixel count density to the count rate from an external blood counter per unit activity concentration in each device. The quality control of the latter is simple and relies on detector stability assessed by measurement of a standard source of similar geometry to a blood sample. The quality control of the tomographic data depends on (i) detector stability, (ii) uniformity of calibration and normalisation sources and (iii) reproducibility of the attenuation correction procedure. A quality control procedure has been developed for an 8 detector ring (15 transaxial plane) tomograph in which detector response is assessed by acquiring data from retractable transmission ring sources. These are scanned daily and a print out of detector efficiencies is produced as well as changes from a given data. This provides the raw data from which decisions on recalibration or renormalisation are made. (orig.)

Bunch-motion feedback for B-factories

International Nuclear Information System (INIS)

Lambertson, G.R.

1992-09-01

The colliding electron and positron beams in a B-factory must have average current of one ampere or more to produce the required luminosity. The high current interacts with structures in the beam tube to drive strong coupled-bunch (c.b.) instabilities. To suppress these instabilities requires negative feedback of the bunch motions. Beam impedances arising from strong rf cavity modes should first be reduced to make the required feedback damping rate practical and the cost economical. In what follows, control of transverse motions will be discussed first, then longitudinal. We shall use the parameters of the 3.1 GeV ring of PEP-II to illustrate the general requirements

Luminosity monitor at PEP

International Nuclear Information System (INIS)

Fox, J.D.; Franklin, M.E.B.

1981-02-01

The luminosity monitor system utilized by the MKII Detector and by the PEP operators is described. This system processes information from 56 photomultipliers and calculates independent luminosities for each of the 3 colliding bunches in PEP. Design considerations, measurement techniques, and sources of error in the luminosity measurement are discussed

Measurements of higher-order mode damping in the PEP-II low-power test cavity

International Nuclear Information System (INIS)

Rimmer, R.A.; Goldberg, D.A.

1993-05-01

The paper describes the results of measurements of the Higher-Order Mode (HOM) spectrum of the low-power test model of the PEP-II RF cavity and the reduction in the Q's of the modes achieved by the addition of dedicated damping waveguides. All the longitudinal (monopole) and deflecting (dipole) modes below the beam pipe cut-off are identified by comparing their measured frequencies and field distributions with calculations using the URMEL code. Field configurations were determined using a perturbation method with an automated bead positioning system. The loaded Q's agree well with the calculated values reported previously, and the strongest HOMs are damped by more than three orders of magnitude. This is sufficient to reduce the coupled-bunch growth rates to within the capability of a reasonable feedback system. A high power test cavity will now be built to validate the thermal design at the 150 kW nominal operating level, as described elsewhere at this conference

Design of an intense positron source for linear colliders

International Nuclear Information System (INIS)

Ida, H.; Yamada, K.; Funahashi, Y.

1994-01-01

The Japan Linear Collider (JLC) requires an intense positron source of 8x10 11 particles per rf-pulse. A computer simulation reveals the possibility of such an intense positron source using 'conventional' technology. In order to relax the limitation of the incident electron energy density due to thermal stress in the converter target, the incident beam radius is enlarged within the range so as not to reduce the positron capture efficiency. A pre-damping ring and beam transport system to the pre-damping ring, which have a large transverse acceptance, play important roles for a high capture efficiency. A prototype positron source has been designed and installed at downstream of 1.54 GeV S-band linac in Accelerator Test Facility (ATF) in order to carry out experiments to develop the essential technology for JLC. The simulated results will be tested in experiments with the prototype positron source. (author)

Trigger drift chamber for the upgraded Mark II detector at PEP

International Nuclear Information System (INIS)

Ford, W.T.; Smith, J.G.; Wagner, S.R.; Weber, P.; White, S.L.; Alvarez, M.; Calvino, F.; Fernandez, E.; Universidad Autonoma de Barcelona

1987-01-01

A small cylindrical track detector was built as an array of single-wire drift cells with aluminized mylar cathode tubes. Point measurement resolution of ∝90 μm was achieved with a drift gas of 50% argon-50% ethane at atmospheric pressure. The chamber construction, electronics, and calibration are discussed. Performance results from PEP colliding-beam data are presented. (orig.)

High-resolution spectrometer at PEP

International Nuclear Information System (INIS)

Weiss, J.M.; HRS Collaboration.

1982-01-01

A description is presented of the High Resolution Spectrometer experiment (PEP-12) now running at PEP. The advanced capabilities of the detector are demonstrated with first physics results expected in the coming months

Transient beam loading in electron-positron storage rings

International Nuclear Information System (INIS)

Wilson, P.B.

1978-01-01

In this note the fundamental of transient beam loading in electron-positron storage rings will be reviewed. The notation, and some of the material, has been introduced previously. The present note is, however, more tutorial in nature, and in addition the analysis is extended to include the transient behaviour of the cavity fields and reflected power between bunch passages. Since we are not bound here by the rigid space limitations of a paper for publication, an attempt is made to give a reasonably coherent and complete discussion of transient beam loading that can hopefully be followed even by the uninitiated. The discussion begins with a consideration of the beam-cavity interaction in the ''single-pass'' limit. In this limit it is assumed that the fields induced in the cavity by the passage of a bunch have decayed essentially to zero by the time the next bunch has arrived. The problem of the maximum energy that can be extracted from a cavity by a bunch is given particular attention, since this subject seems to be the source of some confusion. The analysis is then extended to the ''multiple-pass'' case, where the beam-induced fields do not decay to zero between bunches, and to a detailed consideration of the transient variation of cavity fields and reflected power. The note concludes with a brief discussion of the effect of transient beam loading on quantum lifetime

Positron Accumulator Ring (PAR) power supply

International Nuclear Information System (INIS)

Fathizadeh, M.

1995-01-01

The Positron Accumulator Ring (PAR) consists of 8 dipole magnets connected in series. These magnets are energized via one 12-pulse dc power supply. The power supply consists of four phase controlled half-wave wye group converters. Each of the two half-wave converters are connected through an interphase transformer to obtain a full-wave converter with 120 degrees conduction. The input voltage for these two half-wave converters are 180 degrees apart. The two full-wave converters are connected in parallel through a third interphase transformer. This type of connection of the converters not only provides the required output current, it also improves the input power factor of the power supply. The output of the wye group converters is filtered through a passive L-R-C filter to reduce the ripple content of the output current. At low current values of the power supply the current ripple is high, thus a large filter is needed, which adds to the cost of the power supply, however at high output current levels, the current ripple is less severe. The large size of the filter can be reduced by adding an anti-parallel rectifier diode(D1) to the output of the power supply. A freewheeling diode(D2) is connected before the choke to circulate the current once the power supply is turned off. In order to measure the current in the magnet a high precision, low drift, zero flux current transductor is used. This transductor senses the magnet current which provides a feedback signal to control the gating of the converter's thyristors. A true 14 bit Digital to Analog Converter (DAC) is programmed by the control computer for the required current value, providing a reference for the current regulator. Fast correction of the line transients is provided by a relatively fast voltage loop controlled by a high gain slow response current loop

InverPep: A database of invertebrate antimicrobial peptides.

Science.gov (United States)

Gómez, Esteban A; Giraldo, Paula; Orduz, Sergio

2017-03-01

The aim of this work was to construct InverPep, a database specialised in experimentally validated antimicrobial peptides (AMPs) from invertebrates. AMP data contained in InverPep were manually curated from other databases and the scientific literature. MySQL was integrated with the development platform Laravel; this framework allows to integrate programming in PHP with HTML and was used to design the InverPep web page's interface. InverPep contains 18 separated fields, including InverPep code, phylum and species source, peptide name, sequence, peptide length, secondary structure, molar mass, charge, isoelectric point, hydrophobicity, Boman index, aliphatic index and percentage of hydrophobic amino acids. CALCAMPI, an algorithm to calculate the physicochemical properties of multiple peptides simultaneously, was programmed in PERL language. To date, InverPep contains 702 experimentally validated AMPs from invertebrate species. All of the peptides contain information associated with their source, physicochemical properties, secondary structure, biological activity and links to external literature. Most AMPs in InverPep have a length between 10 and 50 amino acids, a positive charge, a Boman index between 0 and 2 kcal/mol, and 30-50% hydrophobic amino acids. InverPep includes 33 AMPs not reported in other databases. Besides, CALCAMPI and statistical analysis of InverPep data is presented. The InverPep database is available in English and Spanish. InverPep is a useful database to study invertebrate AMPs and its information could be used for the design of new peptides. The user-friendly interface of InverPep and its information can be freely accessed via a web-based browser at http://ciencias.medellin.unal.edu.co/gruposdeinvestigacion/prospeccionydisenobiomoleculas/InverPep/public/home_en. Copyright © 2016 International Society for Chemotherapy of Infection and Cancer. Published by Elsevier Ltd. All rights reserved.

Beam Collimation Studies for the ILC Positron Source

Energy Technology Data Exchange (ETDEWEB)

Drozhdin, A.; /Fermilab; Nosochkov, Y.; Zhou, F.; /SLAC

2008-06-26

Results of the collimation studies for the ILC positron source beam line are presented. The calculations of primary positron beam loss are done using the ELEGANT code. The secondary positron and electron beam loss, the synchrotron radiation along the beam line and the bremsstrahlung radiation in the collimators are simulated using the STRUCT code. The first part of the collimation system, located right after the positron source target (0.125 GeV), is used for protection of the RF Linac sections from heating and radiation. The second part of the system is used for final collimation before the beam injection into the Damping Ring at 5 GeV. The calculated power loss in the collimation region is within 100 W/m, with the loss in the collimators of 0.2-5 kW. The beam transfer efficiency from the target to the Damping Ring is 13.5%.

Skew quad compensation at PEP

International Nuclear Information System (INIS)

Murray, J.J.

1977-10-01

Rotational and focal effects of solenoids used in PEP detectors will cause severe perturbations of machine beam optics and must be corrected. Ordinarily this would be accomplished by the addition of compensating solenoids and adjustment of insertion quadrupole strengths. It has been found that an arbitrary cross plane coupling representing the effects of solenoids and/or skew quads in any combination can be synthesized (or compensated) exactly using a quartet of skew quads combined with other erect transport elements in a wide variety of configurations. Specific skew quad compensating systems for PEP have been designed and are under study by PEP staff. So far no fundamental flaws have been discovered. In view of that, PEP management has tentatively authorized the use of such a system in the PEP-4, PEP-9 experiments and proposes to leave the question open ''without prejudice'' for other experiments. Use of skew quad compensation involves an imponderable risk, of course, simply because the method is new and untested. But in addition to providing the only known method for dealing with skew quad perturbations, skew quad compensation, as an alternate to compensating solenoids, promises to be much cheaper, to require much less power and to occupy much less space in the IR's. The purpose of this note is to inform potential users of the foregoing situation and to explain skew quad compensation more fully. 2 refs., 1 fig., 1 tab

The Danish PEP registry: experience with the use of postexposure prophylaxis (PEP) following sexual exposure to HIV from 1998 to 2006

DEFF Research Database (Denmark)

Lunding, Suzanne; Katzenstein, Terese L; Kronborg, Gitte

2010-01-01

BACKGROUND: Studies indicate that antiretroviral postexposure prophylaxis (PEP) after sexual exposure to HIV reduce the risk of infection considerably. Since 1998 PEP after sexual HIV exposure within the preceding 24 hours, has been available in Denmark. PEP can only be prescribed at clinical...... centers with specialists experienced in HIV treatment. The objective of this study is to describe the use of PEP after sexual exposure from 1998 to 2006. METHODS: The Danish PEP registry collects data from all cases of PEP use in Denmark after exposure to HIV through a structured questionnaire. RESULTS......: There were 374 cases of PEP use after sexual exposure. The incidence increased from 5 cases in 1997 to 87 in 2006. PEP was used by heterosexuals (40%) as well as men who have sex with men (57%). The HIV-status of the source was unknown in 41% of the cases of which 90% involved a source belonging to a high...

Particle-in-Cell Calculations of the Electron Cloud in the ILC Positron Damping Ring Wigglers

International Nuclear Information System (INIS)

Celata, C.M.; Furman, M.A.; Vay, J.-L.; Grote, D.P.

2007-01-01

The self-consistent code suite WARP-POSINST is being used to study electron cloud effects in the ILC positron damping ring wiggler. WARP is a parallelized, 3D particle-in-cell code which is fully self-consistent for all species. The POSINST models for the production of photoelectrons and secondary electrons are used to calculate electron creation. Mesh refinement and a moving reference frame for the calculation will be used to reduce the computer time needed by several orders of magnitude. We present preliminary results for cloud buildup showing 3D electron effects at the nulls of the vertical wiggler field. First results from a benchmark of WARP-POSINST vs. POSINST are also discussed

Pep3p/Pep5p complex: a putative docking factor at multiple steps of vesicular transport to the vacuole of Saccharomyces cerevisiae.

OpenAIRE

Srivastava, A; Woolford, C A; Jones, E W

2000-01-01

Pep3p and Pep5p are known to be necessary for trafficking of hydrolase precursors to the vacuole and for vacuolar biogenesis. These proteins are present in a hetero-oligomeric complex that mediates transport at the vacuolar membrane. PEP5 interacts genetically with VPS8, implicating Pep5p in the earlier Golgi to endosome step and/or in recycling from the endosome to the Golgi. To understand further the cellular roles of Pep3p and Pep5p, we isolated and characterized a set of pep3 conditional ...

Early positron emission tomography response-adapted treatment in stage I and II hodgkin lymphoma

DEFF Research Database (Denmark)

André, Marc P.E.; Girinsky, Théodore; Federico, Massimo

2017-01-01

Purpose Patients who receive combined modality treatment for stage I and II Hodgkin lymphoma (HL) have an excellent outcome. Early response evaluation with positron emission tomography (PET) scan may improve selection of patients who need reduced or more intensive treatments. Methods We performed...

Construction of a positron emission tomograph with 2.4 mm detectors

International Nuclear Information System (INIS)

McIntyre, J.A.; Sprosst, R.L.; Wang, K.

1986-01-01

One-quarter of one ring of a positron tomograph has been constructed. The positron annihilation gamma rays are detected by polished plastic scintillators which direct scintillation light by internal reflection to optical fibers for transmission to the photo-multiplier tubes. By viewing each scintillator with four sets of optical fibers, the number of photomultipliers required for an eight ring tomograph with 1024 detectors per ring (2.4 mm wide detectors) can be reduced from 8192 to 288, and the cost of the tomograph reduced accordingly

Carboxyl-terminal-dependent recruitment of nonmuscle myosin II to megakaryocyte contractile ring during polyploidization.

Science.gov (United States)

Badirou, Idinath; Pan, Jiajia; Legrand, Céline; Wang, Aibing; Lordier, Larissa; Boukour, Siham; Roy, Anita; Vainchenker, William; Chang, Yunhua

2014-10-16

Endomitosis is a unique megakaryocyte (MK) differentiation process that is the consequence of a late cytokinesis failure associated with a contractile ring defect. Evidence from in vitro studies has revealed the distinct roles of 2 nonmuscle myosin IIs (NMIIs) on MK endomitosis: only NMII-B (MYH10), but not NMII-A (MYH9), is localized in the MK contractile ring and implicated in mitosis/endomitosis transition. Here, we studied 2 transgenic mouse models in which nonmuscle myosin heavy chain (NMHC) II-A was genetically replaced either by II-B or by a chimeric NMHCII that combined the head domain of II-A with the rod and tail domains of II-B. This study provides in vivo evidence on the specific role of NMII-B on MK polyploidization. It demonstrates that the carboxyl-terminal domain of the heavy chains determines myosin II localization to the MK contractile ring and is responsible for the specific role of NMII-B in MK polyploidization.

Spectroscopic, Elemental and Thermal Analysis, and Positron Annihilation Studies on Ca(II), Sr(II), Ba(II), Pb(II), and Fe(III) Penicillin G Potassium Complexes

Science.gov (United States)

Refat, M. S.; Sharshara, T.

2015-11-01

The [Pb(Pin)2] · 3H2O, [M(Pin)(H2O)2(Cl)] · nH2O (M = SrII, CaII or BaII; n = 0-1), and [Fe(Pin)2(Cl)(H2O)] · H2O penicillin G potassium (Pin) complexes were synthesized and characterized using elemental analyses, molar conductivity, thermal analysis and electronic spectroscopy techniques. The positron annihilation lifetime (PAL) and Doppler broadening (DB) techniques have been employed to probe the defects and structural changes of Pin ligand and its complexes. The PAL and DB line-shape parameters were discussed in terms of the structure, molecular weight, ligand-metal molar ratio, and other properties of the Pin complexes.

A proposed NSLS x-ray ring upgrade using B factory technology

International Nuclear Information System (INIS)

Blum, E.B.

1995-01-01

A proposed upgrade to the NSLS X-Ray Ring is described that will allow the storage of a 2.4 A. 3 GeV electron beam using technology developed for the PEP-II B factory at SLAC. In this configuration, a peak flux of greater than 10 16 photons/sec/0.1% bandwidth/5 mrad will be produced. The four existing 53 MHz RF cavities will be replaced with eight 476 MHz cavities. Two 952 MHz cavities will also be used to lengthen the bunch, increasing the Touschek life-time. A copper vacuum chamber will be needed to absorb the increased synchrotron radiation and a feedback system may be needed to prevent multi-bunch instabilities

Advanced accelerator research and development

International Nuclear Information System (INIS)

Anon.

1974-01-01

Research and development on the Positron-Electron Project (PEP), the electron rings, the superconducting accelerator (ESCAR), and the superconductivity program are reported. Efforts relating to the proposed PEP include work on: (1) the injection system; (2) the rf system; (3) the main-ring bend magnets; (4) the magnet power supplies and controls; (5) alignment; (6) radiation and shielding; (7) the vacuum system; and (8) conventional facilities (utilities, etc.). Experimental and theoretical work continued on the development of suitably intense electron rings as vehicles for the collective acceleration of ions. The most difficult problem was found to be the longitudinal (negative mass) instability. Design work was begun for ESCAR (Experimental Superconducting Accelerating Ring), a small proton synchrotron and storage ring using superconducting magnets, which should aid in the design of future large superconducting facilities. Magnet development was largely directed toward the detailed design of the dipole units. A superconducting beam transport line was installed at the Bevatron. (PMA)

Charmed and strange baryon production in 29-GeV electron positron collisions

International Nuclear Information System (INIS)

Klein, S.R.

1988-01-01

Baryon production is one of the least understood areas of hadron production in electron positron collisions. Early models of hadronization predicted that very few baryons should be produced. However, experiments have shown a very substantial rate of baryon production, and many different models have been proposed to explain this. One way to test these models, and to further probe the hadronization process is to measure the production rates of different types of baryons. This dissertation presents measurements of the production rates of baryons with different strangeness and spin. The analyses presented here use data taken with the Mark II detector at the PEP storage ring, operating at a center of mass energy of 29 GeV. The Ξ - production rate is measured to be 0.017 ± 0.004 ± 0.004 per hadronic event, Ω - production is measured to be 0.014 ± 0.006 ± 0.004 per hadronic event, and Ξ *0 production is less than 0.006 per hadronic event at a 90% confidence level. These measurements place strong constraints on models of baryon production. In particular, the unexpectedly high rate of Ω - production is difficult to explain in any disquark based model. Semileptonic Λ c + decays have also been observed, with σ(e + e - → Λ c X) * Br(Λ c → eΛX) = 0.0031 ± 0.0012 ± 0.0010 per hadronic event, and σ(e + e - → Λ c X) * Br(Λ c → μΛX) = 0.0024 ± 0.0024 ± 0.0007 per hadronic event. Because neither the branching ratios nor the production rate are well known, it is difficult to interpret these results

Type II GaSb quantum ring solar cells under concentrated sunlight.

Science.gov (United States)

Tsai, Che-Pin; Hsu, Shun-Chieh; Lin, Shih-Yen; Chang, Ching-Wen; Tu, Li-Wei; Chen, Kun-Cheng; Lay, Tsong-Sheng; Lin, Chien-Chung

2014-03-10

A type II GaSb quantum ring solar cell is fabricated and measured under the concentrated sunlight. The external quantum efficiency confirms the extended absorption from the quantum rings at long wavelength coinciding with the photoluminescence results. The short-circuit current of the quantum ring devices is 5.1% to 9.9% more than the GaAs reference's under various concentrations. While the quantum ring solar cell does not exceed its GaAs counterpart in efficiency under one-sun, the recovery of the open-circuit voltages at higher concentration helps to reverse the situation. A slightly higher efficiency (10.31% vs. 10.29%) is reported for the quantum ring device against the GaAs one.

VXI based multibunch detector and QPSK modulator for the PEP-II/ALS/DAΦNE longitudinal feedback system

International Nuclear Information System (INIS)

Young, A.; Fox, J.; Teytelman, D.

1997-04-01

The PEP-II/ALS/DAΦNE feedback systems are complex systems implemented using analog, digital and microwave circuits. The VXI hardware implementation for the Front-end and Back-end analog processing modules is presented. The Front-end module produces a baseband beam phase signal from pickups using a microwave tone burst generator. The Back-end VXI module generates an AM/QPSK modulated signal from a baseband correction signal computed in a digital signal processor. These components are implemented in VXI packages that allow a wide spectrum of system functions including a 120 MHz bandwidth rms detector, reference phase servo, woofer link to the RF control system, standard VXI status/control, and user defined registers. The details of the design and implementation of the VXI modules including performance characteristics are presented

The Danish PEP registry: experience with the use of postexposure prophylaxis (PEP) following sexual exposure to HIV from 1998 to 2006

DEFF Research Database (Denmark)

Lunding, Suzanne; Katzenstein, Terese L; Kronborg, Gitte

2010-01-01

centers with specialists experienced in HIV treatment. The objective of this study is to describe the use of PEP after sexual exposure from 1998 to 2006. METHODS: The Danish PEP registry collects data from all cases of PEP use in Denmark after exposure to HIV through a structured questionnaire. RESULTS......: There were 374 cases of PEP use after sexual exposure. The incidence increased from 5 cases in 1997 to 87 in 2006. PEP was used by heterosexuals (40%) as well as men who have sex with men (57%). The HIV-status of the source was unknown in 41% of the cases of which 90% involved a source belonging to a high...... risk group, and 63% involved exposure by receptive anal intercourse. PEP was administered within 24 hours in 95% of the cases and the median time to initiation (N = 225) was 11.0 hours (range 0.5-60.0). PEP was completed by 65%. CONCLUSIONS: This nationwide study showed a steady but moderate increase...

Positron ring system using Anger-type detectors. Progress report for period ending December 31, 1984

International Nuclear Information System (INIS)

Muehllehner, G.

1984-08-01

A single-ring positron camera consisting of six position-sensitive single-crystal detectors has been constructed, and its performance has been evaluated for a variety of applications. The major factors limiting its performance have been established, and methods to overcome some of these limitations have been explored. At low data rates, a spatial resolution of 6.5 mm full-width-half-maximum (FWHM) has been measured in the final reconstructed image, and at high data rates a spatial resolution below 8 mm FWHM has been achieved. Initial problems in imaging extended objects have been overcome through careful normalization of the data and by using an iterative reconstruction algorithm which is insensitive to the missing data due to the gaps between the detectors. 10 figures

Search for heavy neutrino production at PEP

International Nuclear Information System (INIS)

Feldman, G.J.

1985-10-01

We report a search for long-lived heavy neutrinos produced by the neutral weak current in e + e - annihilation at 29 GeV at PEP. Data from the Mark II detector are examined for evidence of events with one or two separated vertices in the radial range of 2 mm to 10 cm. No events were found that were consistent with the hypothesis of heavy neutrino production, eliminating the possibility of heavy neutrinos with decay lengths of 1 to 20 cm in mass range 1 to 13 GeV/c 2

PEP II: RF and feedback R ampersand D

International Nuclear Information System (INIS)

Hindi, H.: Fox, J.; Eisen, N.; Linscott, I.; Oxoby, G.; Pendleton, R.; Sapozhnikov, L.; Schwarz, H.D.; Rimmer, R.; Lambertson, A.; Voelker, F.; Serio, M.

1992-11-01

The key elements of the PEP 11 approach to dealing with the problem of coupled-bunch instabilities are presented. The approach involves using warm copper RF cavities with damping waveguides (above the cutoff of the fundamental) attached to the cavity walls. These couple out the troublesome higher-order modes (HOMs) into absorbing loads, while the fundamental mode remains in the cavity. The Q of the worst HOM is reduced to below 70. Instabilities due to residual coupling are damped using a bunch-by-bunch feedback system, which is implemented using digital signal processors. A prototype cavity has been built and the concept of HOM damping has been verified. A prototype feedback system has been built and tested at SPEAR. Results to date indicate that the combination of damped cavities and bunch-by-bunch feedback provide a very effective means of dealing with the problem

Focusing an antimatter beam with matter

CERN Document Server

CERN. Geneva

2000-01-01

An experiment at the Stanford Linear Accelerator Center has recently focused positron beams by means of a plasma lens. This is the first time this process has been observed. The process started with a positron beam from the SLAC PEP-II positron source. This was sent through a damping ring and then accelerated to 28.5 GeV in the SLAC linac with a bunch intensity of 1-2*10/sup 10/. The beam was delivered to the Final Focus Test Beam Facility (FFTB) at a rate of 1 or 10 Hz. At the focal point of the FFTB transport, a special plasma chamber contains a 3 mm diameter pulsed gas nozzle through which either hydrogen or nitrogen gas is "puffed" into the ultrahigh vacuum system at plenum gas pressures up to 75 atm with a discharge time of 800 mu s. The gas is pumped off by a Roots-type pump. On either side of the central chamber are differential pumping sections semi- isolated from each other by thin titanium windows with small (2-5 mm diameter) apertures for the positron beams to pass through. These sections are evacu...

Jet cross sections in electron-positron annihilation

International Nuclear Information System (INIS)

Sharpe, S.R.

1983-08-01

There are few, if any, detailed tests of QCD at present. I disucss the problems associated with testing QCD and argue that the three jet angular distribution in electron-positron annihilation is a good quantity to use because it minimizes the sensitivity to nonperturbative effects and provides a test of the detailed structure of QCD. However, for such a test to be possible, the perturbation expansion must be well behaved. I present a calculation of the perturbative corrections using two different generalizations of the Sterman-Weinberg two-jet cross section. I argue that because of the uncertainties in our understanding of hadronization it is necessary that the corrections to both these cross sections be small. In presenting the results I use the recent proof of Mukti and Sterman that all the logarithms can be resummed. I find that at Z-factory energies there is a substantial region of parameters defining the jets for which the correction is small, but that there is no such region at PEP/PETRA energies. This problem at PEP/PETRA energies is made worse by the results of a study of the effects of hadronization. Using a simple model I find very significant effects at PEP/PETRA energies that would make a test difficult. These effects do not, however, present problems at Z-factory energies. I conclude that, even if there are further theoretical advances, testing QCD at PEP/PETRA energies using the three-jet angular distribution will be very difficult. However, this distribution can be used to test QCD in a detailed way at Z-factory energies. The corrected results, furthermore, show a systematic difference from the lowest order result that may be measurable at Z-factory energies. If this effect could be measured it would provide a yet more detailed test of QCD, testing, for example, the three gluon coupling. 66 references

The Mark II detector for the SLC

International Nuclear Information System (INIS)

Abrams, G.; Baden, A.R.; Boyer, J.; Butler, F.; Drell, P.S.; Fay, J.; Gidal, G.; Goldhaber, G.; Haggerty, J.; Harr, R.; Hearty, C.; Herrup, D.; Holmgren, S.O.; Jaffre, M.; Juricic, I.; Kadyk, J.A.; Kral, J.F.; Levi, M.E.; Lynch, G.R.; Richman, J.D.; Rouse, F.R.; Schaad, M.W.; Schmidke, W.B.; Schumm, B.A.; Trilling, G.H.; Wood, D.R.; Akerlof, C.; Bonvicini, G.; Chapman, J.; Chmeissani, M.; Frey, R.; Gero, E.; Hong, S.J.; Koska, W.; Nitz, D.; Petradza, M.; Thun, R.; Tschirhart, R.; Veltman, H.; Alexander, J.P.; Ballam, J.; Barklow, T.; Bartelt, J.; De Boer, W.; Boyarski, A.; Braune, K.; Bulos, F.; Burke, D.L.; Cords, D.; Coupal, D.P.; Destaebler, H.C.; Dorfan, J.M.; Feldman, G.J.; Fernandes, D.; Field, R.C.; Fordham, C.; Fujino, D.; Gan, K.K.; Glanzman, T.; Grosse-Wiesmann, P.; Hanson, G.; Hayes, K.; Himel, T.; Hutchinson, D.; Innes, W.R.; Jacobsen, R.G.; Jaros, J.A.; Jung, C.K.; Karlen, D.; Klein, S.R.; Koetke, D.; Komamiya, M.; Kowalski, L.A.; Kozanecki, W.; Lankford, A.J.; Larsen, R.R.; Lueth, V.; Mattison, T.; Moffeit, K.C.; Mueller, L.; Munger, C.T.; Nash, J.; Ong, R.A.; O'Shaughnessy, K.F.; Perl, J.; Perl, M.L.; Perrier, F.; Petersen, A.; Pitthan, R.; Riles, K.; Swartz, M.; Taylor, R.E.; Van Kooten, R.; Voruganti, P.; Weigend, A.; Woods, M.; Wormser, G.; Wright, R.; Alvarez, M.; Calvino, F.; Fernandez, E.; Ford, W.T.; Hinshaw, D.A.; Rankin, P.; Smith, J.G.; Wagner, S.R.; Weber, P.; White, S.L.; Averill, D.; Blockus, D.; Brabson, B.; Brom, J.M.; Murray, W.N.; Ogren, H.; Rust, D.R.; Snyder, A.; Yurko, M.; Barish, B.C.; Hawkes, C.M.; Hoenk, M.; Kuhlen, M.; Li, Z.; McKenna, J.A.; Milliken, B.D.; Nelson, M.E.; Peck, C.; Porter, F.C.; Soderstrom, E.; Stroynowski, R.; Weinstein, A.J.; Weir, A.J.; Wicklund, E.; Wolf, R.C.; Wu, D.Y.; Barnett, B.A.; Boswell, C.; Dauncey, P.; Drewer, D.C.; Harral, B.; Hylen, J.; Matthews, J.A.J.; Stoker, D.P.; Vejcik, S.; Breakstone, A.; Cence, R.J.; Gong, X.; Harris, F.A.; Koide, A.; Parker, S.I.; Green, A.; Lawrence Berkeley Lab., CA; California Univ., Berkeley

1989-01-01

The Mark II detector has been upgraded in preparation for its role as the first detector to take data at the Stanford Linear Collider. The new detector components include the central drift chamber, the time-of-flight system, the coil, the endcap electromagnetic calorimeters and the beam energy and luminosity measuring devices. There have also been improvements in detector hermeticity. All of the major components were installed for a test run at the PEP storage ring (√s=29 GeV) in 1985. This paper describes the upgraded detector, including its trigger and data acquisition systems, and gives performance figures for its components. Future improvements are also discussed. (orig.)

Polarized positron sources for the future linear colliders

International Nuclear Information System (INIS)

Chaikovska, I.

2012-01-01

This thesis introduces the polarized positron source as one of the key element of the future Linear Collider (LC). In this context, the different schemes of the polarized positron source are described highlighting the main issues in this technology. In particular, the main focus is on the Compton based positron source adopted by the CLIC as a preferred option for the future positron source upgrade. In this case, the circularly polarized high energy gamma rays resulting from Compton scattering are directed to a production target where an electromagnetic cascade gives rise to the production of positrons by e + -e - pair conversion. To increase the efficiency of the gamma ray production stage, a multiple collision point line integrated in energy recovery linac is proposed. The simulations of the positron production, capture and primary acceleration allow to estimate the positron production efficiency and provide a simple parametrization of the Compton based polarized positron source in the view of the future LC requirements. The storage ring based Compton source option, so-called Compton ring, is also described. The main constraint of this scheme is given by the beam dynamics resulting in the large energy spread and increased bunch length affecting the gamma ray production rate. An original theoretical contribution is shown to calculate the energy spread induced by Compton scattering. Moreover, an experiment to test the gamma ray production by Compton scattering using a state-of-art laser system developed at LAL has been conducted in the framework of the 'Mighty Laser' project at the ATF, KEK. The experimental layout as well as the main results obtained are discussed in details. The studies carried out in this thesis show that the polarized positron source based on Compton scattering is a promising candidate for the future LC polarized positron source. (author)

Precision PEP-II optics measurement with an SVD-enhanced Least-Square fitting

Science.gov (United States)

Yan, Y. T.; Cai, Y.

2006-03-01

A singular value decomposition (SVD)-enhanced Least-Square fitting technique is discussed. By automatic identifying, ordering, and selecting dominant SVD modes of the derivative matrix that responds to the variations of the variables, the converging process of the Least-Square fitting is significantly enhanced. Thus the fitting speed can be fast enough for a fairly large system. This technique has been successfully applied to precision PEP-II optics measurement in which we determine all quadrupole strengths (both normal and skew components) and sextupole feed-downs as well as all BPM gains and BPM cross-plane couplings through Least-Square fitting of the phase advances and the Local Green's functions as well as the coupling ellipses among BPMs. The local Green's functions are specified by 4 local transfer matrix components R12, R34, R32, R14. These measurable quantities (the Green's functions, the phase advances and the coupling ellipse tilt angles and axis ratios) are obtained by analyzing turn-by-turn Beam Position Monitor (BPM) data with a high-resolution model-independent analysis (MIA). Once all of the quadrupoles and sextupole feed-downs are determined, we obtain a computer virtual accelerator which matches the real accelerator in linear optics. Thus, beta functions, linear coupling parameters, and interaction point (IP) optics characteristics can be measured and displayed.

Coherent x-rays from PEP

International Nuclear Information System (INIS)

Baird, S.; Nuhn, H.-D.; Tatchyn, R.; Winick, H.; Fisher, A.S.; Gallardo, J.C.; Pellegrini, C.

1991-01-01

This paper explores the use of a large-circumference, high-energy, electron-positron collider such as PEP to drive a free-electron laser (FEL), producing high levels of coherent power at short wavelengths. The author consider Self-Amplified Spontaneous Emission (SASE), in which electron bunches with low emittance, high peak current and small energy spread radiate coherently in a single passthrough a long undulator. As the electron beam passes down the undulator, its interaction with the increasingly intense spontaneous radiation causes a bunch density modulation at the optical wavelength, resulting in stimulated emissional growth of coherent power in a single pass. The need for optical-cavity mirrors, which place a lower limit on the wavelength of a conventional FEL oscillator, is avoided. The authors explore various combinations of electron-beam and undulator parameters, as well as special undulator designs and optical klystrons (OK), to reach high average or peak coherent power at wavelengths around 40 angstrom by achieving significant exponential gain or full saturation. Examples are presented for devices that achieve high peak coherent power (up to about 400 MW) with lower average coherent power (about 20 mW) and other devices which produce a few watts of average coherent power

Multi-Bunch Longitudinal Dynamics and Diagnostics via a Digital Feedback System at PEP-II, DAFNE, ALS and SPEAR

International Nuclear Information System (INIS)

Fox, John D

1999-01-01

A bunch-by-bunch longitudinal feedback system based on a programmable DSP architecture is used to study coupled-bunch motion and its sources. Experimental results are presented from PEP-II, DAΦNE, ALS and SPEAR to highlight the operational experience from 4 installations, plus show novel accelerator diagnostics possible with the digital processing system. Modal growth and damping rates are measured via short (20 ms) transient recordings for unstable and stable coupled-bunch modes. Data from steady-state measurements are used to identify unstable modes and noise-driven beam motion. A novel impedance measurement technique is presented which reveals the longitudinal impedance as a function of frequency. This technique uses the measured synchronous phase and charge of every bucket to calculate the impedance seen by the beam at revolution harmonics

Damping Ring R&D at CESR-TA

Energy Technology Data Exchange (ETDEWEB)

Rubin, David L. [Cornell Univ., Ithaca, NY (United States). Dept. of Physics

2015-01-23

Accelerators that collide high energy beams of matter and anti-matter are essential tools for the investigation of the fundamental constituents of matter, and the search for new forms of matter and energy. A “Linear Collider” is a machine that would bring high energy and very compact bunches of electrons and positrons (anti-electrons) into head-on collision. Such a machine would produce (among many other things) the newly discovered Higgs particle, enabling a detailed study of its properties. Among the most critical and challenging components of a linear collider are the damping rings that produce the very compact and intense beams of electrons and positrons that are to be accelerated into collision. Hot dilute particle beams are injected into the damping rings, where they are compressed and cooled. The size of the positron beam must be reduced more than a thousand fold in the damping ring, and this compression must be accomplished in a fraction of a second. The cold compact beams are then extracted from the damping ring and accelerated into collision at high energy. The proposed International Linear Collider (ILC), would require damping rings that routinely produce such cold, compact and intense beams. The goal of the Cornell study was a credible design for the damping rings for the ILC. Among the technical challenges of the damping rings; the development of instrumentation that can measure the properties of the very small beams in a very narrow window of time, and mitigation of the forces that can destabilize the beams and prevent adequate cooling, or worse lead to beam loss. One of the most pernicious destabilizing forces is due to the formation of clouds of electrons in the beam pipe. The electron cloud effect is a phenomenon in particle accelerators in which a high density of low energy electrons, build up inside the vacuum chamber. At the outset of the study, it was anticipated that electron cloud effects would limit the intensity of the positron ring

Design and verification of controllers for longitudinal oscillations using optimal control theory and numerical simulation: Predictions for PEP-II

International Nuclear Information System (INIS)

Hindi, H.; Prabhakar, S.; Fox, J.; Teytelman, D.

1997-12-01

The authors present a technique for the design and verification of efficient bunch-by-bunch controllers for damping longitudinal multibunch instabilities. The controllers attempt to optimize the use of available feedback amplifier power--one of the most expensive components of a feedback system--and define the limits of closed loop system performance. The design technique alternates between analytic computation of single bunch optimal controllers and verification on a multibunch numerical simulator. The simulator identifies unstable coupled bunch modes and predicts their growth and damping rates. The results from the simulator are shown to be in reasonable agreement with analytical calculations based on the single bunch model. The technique is then used to evaluate the performance of a variety of controllers proposed for PEP-II

Design and simulation of fast pulsed kicker/bumper units for the positron accumulator ring at APS

International Nuclear Information System (INIS)

Wang, Ju; Volk, G.J.

1991-01-01

In the design of fast pulsed kicker/burner units for a positron accumulator ring (PAR) at APS, different pulse forming networks (PFN) are considered and different structures for the magnet are studied and simulated. Three fast pulsed kicker/bumper magnets are required in PAR for the beam injection and/or extraction at 450 MeV. These magnets have the same design because they have identical specifications and are expected to produce identical magnetic fields. Each kicker/bumper magnet is required to generate a magnetic field of 0.06 T with rise-time of 80 ns, a flat-top of 80 ns and a fall-time of 80 ns. This paper describes some design considerations and computer simulation results of different designs

Study of the machine background induced by the PEP-II collider with a mini-TPC. Study of the doubly-charmed decay of the B meson with the detector BaBar

International Nuclear Information System (INIS)

Trincaz-Duvoid, S.

2001-01-01

The work presented in this thesis is divided into two parts. The first one deals with the machine background induced by the PEP-II collider. This study has been performed with a mini-TPC before the start of the BaBar experiment. The second part concerns the measurements of the branching ratio of the decay modes B 0 → D *- D(*) 0 K + and of the inclusive branching ratio Br(B 0 → K ± X). These measurements have been obtained with the first BaBar data. During the commissioning of the PEP-II collider, the charged tracks rate close to the interaction point has been measured with the mini-TPC. This study has pointed to the fact that the machine background was much higher than predicted by the simulation. These bad background conditions were due to the poor quality of the vacuum in the rings. This relatively high pressure in the rings produces electro-magnetic showers at the interaction point due to beam gas interactions. The potential risks for the BaBar detector due to the machine backgrounds have been clearly pointed out by the studies performed for this thesis. The addition of some collimators and a deep understanding of the machine have greatly reduced the background. Nevertheless, the radiation level in BaBar is continuously monitored in order to protect the detector. The study of the b → cc-bar channel is an important point for the understanding of the overall picture of the B meson decay. With an integrated luminosity of 17.3 fb -1 recorded by the BaBar detector the following branching ratio using exclusive reconstruction technique have been measured: Br(B 0 → D *- D 0 K + ) = (0.29 ± 0.06 (stat) ± (syst)) % Br(B 0 → D *- D *0 K + ) = (1.16 ± 0.15 (stat) ± 0.16 (syst)) % A partial reconstruction has also been developed. With an integrated luminosity of 8.9 fb -1 , the branching ratio of B 0 into D *- D 0 K + has been measured: Br(B 0 → D *- D 0 K + ) = (0.45 ± 0.12 (stat) ± 0.25 (syst)) % This result is in good agreement with the value obtained

Radiotherapy and chemotherapy in stages I and II non-Hodgkin's lymphomas of Waldeyer's ring

International Nuclear Information System (INIS)

Hayabuchi, Naofumi; Jingu, Kenichi; Miyoshi, Makoto; Akasi, Yuko; Masuda, Koji; Komiyama, Sotaro; Kikuchi, Masahiro.

1990-01-01

Sixty-four patients with stages I and II non-Hodgkin's lymphomas (NHL) involving Waldeyer's ring treated between 1970 and 1987 were reviewed. Patients with stage II NHL were subdivided into stage II1 (limited type) and stage II2 (advanced type) from the state of neck nodes. Stage II1 was defined as involvement of unilateral cervical nodes less than 4 cm in diameter as well as Waldeyer's ring involvement. Other stage II cases were classified as stage II2. All 17 patients with stage I HNL were treated with radiation therapy alone. Their diseases were well controlled, and none of them died of causes related to the lymphoma. Among 14 patients with stage II1 NHL, the 5-year survival rate for the 9 patients treated with radiation therapy alone was 87.5%. Until 1982, 19 of 21 patients with stage II2 NHL treated with radiation therapy alone or radiation therapy and adjuvant chemotherapy (VEMP or COPP) died within 5 years mainly of disseminated diseases. Since 1983, CHOP had been used as the main treatment as well as radiotherapy for the 12 stage II2 NHL patients. So far, only 3 of them relapsed and 2 of them died of causes related to the lymphoma. Only 1 of these 12 patients was T-cell lymphoma compared to 7 of 9 stage II2 patients before 1982. This suggests that patients with stage I and those with limited stage II can be safely treated with radiotherapy. Also aggressive chemotherapy as well as radiotherapy should be used for patients with advanced stage II HNL involving Waldeyer's ring. (author)

New particle searches at PEP

International Nuclear Information System (INIS)

Berley, D.; Bulos, F.; Cheng, D.

1988-01-01

The new particles that could be produced at PEP are discussed in terms of their specific signatures and production rates. We find that a small number of general signatures characterize these particles. Backgrounds associated with the general signatures are considered and necessary rejection rates are calculated. We describe several typical detectors and tabulate the requirements they place on the PEP machine and the experimental areas. 10 figs., 2 tabs

Ring Expansion and Rearrangements of Rhodium(II) Azavinyl Carbenes

Science.gov (United States)

Selander, Nicklas; Worrell, Brady T.

2013-01-01

An efficient, regioselective and convergent method for the ring expansion and rearrangement of 1-sulfonyl-1,2,3-triazoles under rhodium(II)-catalyzed conditions is described. These denitrogenative reactions form substituted enaminone and olefin-based products, which in the former case can be further functionalized to unique products rendering the sulfonyl triazole traceless. PMID:23161725

Concepts for a slow-positron target at the advanced photon source

International Nuclear Information System (INIS)

Lessner, E.; White, M.

1997-01-01

The Advanced Photon Source (APS) linear accelerator beam could be used to produce slow positrons during the hours between the storage ring injection cycles. Initial concepts for the design of a target that is optimized for slow-positron production are discussed, and simulation results are presented. Some possible ways to increase the nominal linac beam power for improved slow-positron production are also discussed

Storage Rings

International Nuclear Information System (INIS)

Fischer, W.

2010-01-01

Storage rings are circular machines that store particle beams at a constant energy. Beams are stored in rings without acceleration for a number of reasons (Tab. 1). Storage rings are used in high-energy, nuclear, atomic, and molecular physics, as well as for experiments in chemistry, material and life sciences. Parameters for storage rings such as particle species, energy, beam intensity, beam size, and store time vary widely depending on the application. The beam must be injected into a storage ring but may not be extracted (Fig. 1). Accelerator rings such as synchrotrons are used as storage rings before and after acceleration. Particles stored in rings include electrons and positrons; muons; protons and anti-protons; neutrons; light and heavy, positive and negative, atomic ions of various charge states; molecular and cluster ions, and neutral polar molecules. Spin polarized beams of electrons, positrons, and protons were stored. The kinetic energy of the stored particles ranges from 10 -6 eV to 3.5 x 10 12 eV (LHC, 7 x 10 12 eV planned), the number of stored particles from one (ESR) to 1015 (ISR). To store beam in rings requires bending (dipoles) and transverse focusing (quadrupoles). Higher order multipoles are used to correct chromatic aberrations, to suppress instabilities, and to compensate for nonlinear field errors of dipoles and quadrupoles. Magnetic multipole functions can be combined in magnets. Beams are stored bunched with radio frequency systems, and unbunched. The magnetic lattice and radio frequency system are designed to ensure the stability of transverse and longitudinal motion. New technologies allow for better storage rings. With strong focusing the beam pipe dimensions became much smaller than previously possible. For a given circumference superconducting magnets make higher energies possible, and superconducting radio frequency systems allow for efficient replenishment of synchrotron radiation losses of large current electron or positron beams

Luminosity with more bunches in PEP

International Nuclear Information System (INIS)

Corbett, W.J.

1990-12-01

The near term accelerator physics program for PEP includes experiments in a collider mode with up to 9 bunches in each beam. In this memo, luminosity data from the 3 x 3 configuration is first used to calculate vertical beam size, emittance and tune shift as a function of current. The data is then used to extrapolate to the case with either 6 x 6 or 9 x 9 bunches colliding in PEP. Vertical emittance growth from the separated bunch optics and dispersion at the IP are included in the calculations. The conclusion is that given a 90 mA current drive limitation in PEP, operating with 6 x 6 bunches yields the maximum luminosity. 9 refs., 6 figs

Topics in electron-positron interactions

International Nuclear Information System (INIS)

Soeding, P.

1983-01-01

This chapter investigates the collision of an electron and a positron in a high energy storage ring in which a large energy Q=W=√s=2 E /SUB beam/ is dumped into a tiny region of space-time. If the electron and positron annihilate each other almost all of this energy becomes concentrated in a single field quantum. Points out 3 consequences: 1) all flavored particles existing in nature are expected to be pair-produced provided their mass is not larger than W/2; 2) the pair production process acts as an effective ''filter'' for fundamental (i.e. pointlike) particles; and 3) particles without flavor (i.e. the gluons) are not directly pair-produced in e - e + interactions. Discusses basic processes; probing QED and lepton structure; hadron production at high energies; resonances; e - e + storage rings; detectors; electroweak interaction and new particles (leptons, quarks); restrictions on a more general weak interaction scenario; limits on pair production of scalar particles; and jets and QCD tests

Butyrate transcriptionally enhances peptide transporter PepT1 expression and activity.

Directory of Open Access Journals (Sweden)

Guillaume Dalmasso

Full Text Available BACKGROUND: PepT1, an intestinal epithelial apical di/tripeptide transporter, is normally expressed in the small intestine and induced in colon during chronic inflammation. This study aimed at investigating PepT1 regulation by butyrate, a short-chain fatty acid produced by commensal bacteria and accumulated inside inflamed colonocyte. RESULTS: We found that butyrate treatment of human intestinal epithelial Caco2-BBE cells increased human PepT1 (hPepT1 promoter activity in a dose- and time-dependent manner, with maximal activity observed in cells treated with 5 mM butyrate for 24 h. Under this condition, hPepT1 promoter activity, mRNA and protein expression levels were increased as assessed by luciferase assay, real-time RT-PCR and Western blot, respectively. hPepT1 transport activity was accordingly increased by approximately 2.5-fold. Butyrate did not alter hPepT1 mRNA half-life indicating that butyrate acts at the transcriptional level. Molecular analyses revealed that Cdx2 is the most important transcription factor for butyrate-induced increase of hPepT1 expression and activity in Caco2-BBE cells. Butyrate-activated Cdx2 binding to hPepT1 promoter was confirmed by gel shift and chromatin immunoprecipitation. Moreover, Caco2-BBE cells overexpressing Cdx2 exhibited greater hPepT1 expression level than wild-type cells. Finally, treatment of mice with 5 mM butyrate added to drinking water for 24 h increased colonic PepT1 mRNA and protein expression levels, as well as enhanced PepT1 transport activity in colonic apical membranes vesicles. CONCLUSIONS: Collectively, our results demonstrate that butyrate increases PepT1 expression and activity in colonic epithelial cells, which provides a new understanding of PepT1 regulation during chronic inflammation.

The Woods Hole Partnership Education Program (PEP) (Invited)

Science.gov (United States)

Jearld, A.; Liles, G.; Gutierrez, B.

2013-12-01

In March 2009, the Woods Hole Diversity Initiative (WHDI) launched the Partnership Education Program (PEP), a multi-institutional effort to increase diversity in the student population (and ultimately the work force) in the Woods Hole science community. PEP, a summer research internship program, is open to students of all backgrounds but is designed especially to provide opportunities for individuals from populations under-represented in science, technology, engineering, and mathematics (STEM) and who otherwise would not have had the opportunity to come to Woods Hole to study or do research. A month-long course, 'Ocean and Environmental Sciences: Global Climate Change,' sets the stage for their summer research projects. The PEP model is emerging as an effective and sustainable approach to bringing students into the STEM research community. PEP is carefully structured to provide critical support for students as they complete their undergraduate experience and prepare for careers and/or graduate school. In its first five years, PEP has brought to the Woods Hole science community more than 75 students from over 50 colleges and universities, including many that do not typically send talent into marine and/or ecological research. PEP is unusual (perhaps even unique) in that it is a collaborative initiative involving seven partner institutions. Working together, the PEP collaborative has established a critical mass of under-represented students who are now in graduate school and/or working in STEM areas.

PRELIMINARY IMPEDANCE BUDGET FOR NSLS-II STORAGE RING.

Energy Technology Data Exchange (ETDEWEB)

BLEDNYKH,A.; KRINSKY, S.

2007-06-25

The wakefield and impedance produced by the components of the NSLS-II storage ring have been computed for an electron bunch length of 3mm rms. The results are summarized in a table giving for each component, the loss factor ({kappa}{sub {parallel}}), the imaginary part of the longitudinal impedance at low frequency divided by the revolution harmonic (ImZ{sub {parallel}}/n), and the transverse kick factors ({kappa}{sub x}, {kappa}{sub y}).

Beta spectra. II-Positron spectra

International Nuclear Information System (INIS)

Grau, A.; Garcia-Torano, E.

1981-01-01

Using the Fermi theory of beta decay, the beta spectra for 30 positron emitters have been computed, introducing a correction factor for unique forbidden transitions. The spectra are ploted vs. energy, once normalised, and tabulated with the related Fermi functions. The average and median energies are calculated. (author)

RF HEATING AND TEMPERATURE OSCILLATIONS DUE TO A SMALL GAP IN A PEP-II VACUUM CHAMBER

International Nuclear Information System (INIS)

Novokhatski, Alexander

2003-01-01

Wake fields excited in a small gap of a vacuum chamber by ampere beams can have enough amplitude to heat the chamber. The electric component of these fields can be above the arcing limit. Usually flange connections in a vacuum chamber contain a vacuum gasket and an inner RF gasket. If a small gap occurs between the RF gasket and flange surface, wake fields can heat the flanges. The flanges are usually made of stainless steel, which efficiently absorbs RF power. Some flanges consist of two parts (like a vacuum valve flange) and are mechanically connected but have poor thermal contact. A temperature rise can lengthen the inner part of the flange and make firmer the thermal contact to the outer part of the flange. The heat will then flow to the outer part of the flange, which is air and water-cooled. This cooling lowers the flange temperature and the thermal contact becomes poor again. This ''quasi'' periodic mechanism can explain the nature of temperature oscillations observed at several locations in PEP-II, the SLAC B-factory

Superconducting snake with the field of 75 kGs for the VEPP-2M electron-positron storage ring

International Nuclear Information System (INIS)

Anashin, V.V.; Vasserman, I.B.; Vlasov, A.M.

1985-01-01

Superconducting ''snake'' with the field of 75 kG is established in the VEPP-2M electron-positron storage ring for increase of colliding beam luminosity up to 2x10 31 cmsup(-2)sdup(-1) in the energy range from 2x200 to 2x700 MeV. The ''snake'' comprises three central magnets with the field of 75 kG and two side ones with the field of 45 kG and it is placed in one of rectilinear experimental gaps. Description of design peculiarities of the ''snake'' and its parameters are given. Parameters of beams with switched on and switched off ''snake'' as well as parameters of coils and superconducting wire are presented

Search for highly interacting fractionally charged particles at PEP

International Nuclear Information System (INIS)

Wlodzimierz, G.

1982-01-01

Fractionally charged, highly interacting particles produced in e + e - annihilation at 20 GeV c.m. energy have been search for. The experiment was performed at the positron electron storage ring (PEP) at the Stanford Linear Accelerator Center (SLAC). The search used in the innermost part of the two-arm Free Quark Search (FQS) detector. This part was called the Thin Front End (TFE) and it covered 1/3 of the full solid angle. Each of its arms consisted of five multiwire proportional chambers (MWPC's), used for tracking and dE/dx measurement, and three hodoscopes of 0.16 cm thick Pilot F scintillator. The total thickness of the five MWPC's and the beam pipe was 0.007 hadronic collision lengths (lambda/sub c/). No candidates for fractionally charged particles were found. Upper limits on R/sub q anti q/ = sigma(e + e - →q anti q)/sigma(e + e - →μμ) are between: (1) 0.7% to 7% for quark interaction lengths (lambda/sub q/) equal to lambda/sub c/ and between 3% and 33% for lambda/sub q/ = 100lambda/sub c/ for Q = 1/3e quark charge and for quark masses up to 13 GeV/c 2 ; (2) 2% to 38% for lambda/sub q/ - lambda/sub c/ and from 7% to 160% for lambda/sub q/ = 100lambda/sub c/ for Q = 2/3e quark charge and for masses up to 8 GeV/c 2 . In the inclusive production channel the upper limits on R/sub q/ = sigma(e + e - →qqX)/sigma(e + e - →μμ) are for charge 1/3e only. R/sub q/ varies from 2% to 11% for lambda/sub q/ = lambda/sub c/ and from 3% to 16% for lambda/sub q/ = 100lambda/sub c/ and for quark masses up to 6.5 GeV/c 2 . These are the first limits on the production of fractionally charged particles with lambda/sub q/ = 100lambda/sub c/

[Experiment studies of electron-positron interactions at the Stanford Linear Accelerator Center

International Nuclear Information System (INIS)

Hertzbach, S.S.; Kofler, R.R.

1993-01-01

The High Energy Physics group at the University of Massachusetts has continued its' program of experimental studies of electron-positron interactions at the Stanford Linear Accelerator Center (SLAC). The group activities have included: analysis of data taken between 1982 and 1990 with the TPC detector at the PEP facility, continuing data collection and data analysis using the SLC/SLD facility, planning for the newly approved B-factory at SLAC, and participation in design studies for future high energy linear colliders. This report will briefly summarize these activities

Critical Role of PepT1 in Promoting Colitis-Associated Cancer and Therapeutic Benefits of the Anti-inflammatory PepT1-Mediated Tripeptide KPV in a Murine ModelSummary

Directory of Open Access Journals (Sweden)

Emilie Viennois

2016-05-01

Full Text Available Background & Aims: The human intestinal peptide transporter 1 (hPepT1, is expressed in the small intestine at low levels in the healthy colon and up-regulated during inflammatory bowel disease. hPepT1 plays a role in mouse colitis and human studies have shown that chronic intestinal inflammation leads to colorectal cancer (colitis-associated cancer; CAC. Hence, we assessed here the role of PepT1 in CAC. Methods: Mice with hPepT1 overexpression in intestinal epithelial cells (transgenic [TG] or PepT1 (PepT1-knockout [KO] deletion were used and CAC was induced by azoxymethane/dextran sodium sulfate. Results: TG mice had larger tumor sizes, increased tumor burdens, and increased intestinal inflammation compared with wild-type (WT mice. Conversely, tumor number and size and intestinal inflammation were decreased significantly in PepT1-KO mice. Proliferating crypt cells were increased in TG mice and decreased in PepT1-KO mice. Analysis of human colonic biopsy specimens showed increased expression of PepT1 in patients with colorectal cancer, suggesting that PepT1 might be targeted for the treatment of CAC. The use of an anti-inflammatory tripeptide Lys-Pro-Val (KPV transported by PepT1 was able to prevent carcinogenesis in WT mice. When administered to PepT1-KO mice, KPV did not trigger any of the inhibitory effect on tumorigenesis observed in WT mice. Conclusions: The observations that PepT1 was highly expressed in human colorectal tumor and that its overexpression and deletion in mice increased and decreased colitis-associated tumorigenesis, respectively, suggest that PepT1 is a potential therapeutic target for the treatment of colitis-associated tumorigenesis. Keywords: Colitis-Associated Cancer, Intestinal Inflammation, PepT1, KPV Peptide

Positron Options for the Linac-Ring LHeC

CERN Document Server

Zimmermann, F; Papaphilippou, Y; Schulte, D; Sievers, P; Rinolfi, L; Variola, A; Zomer, F; Braun, H H; Yakimenko, V; Bulyak, E V; Klein, M

2012-01-01

The full physics program of a future Large Hadron electron Collider (LHeC) [1] requires both pe+ and pe− collisions. For a pulsed 140-GeV or an ERL-based 60-GeV Linac-Ring LHeC this implies a challenging rate of, respectively, about 1.8 × 1015 or 4.4 × 1016 e+/s at the collision point, which is about 300 or 7000 times the rate previously obtained, at the SLAC Linear Collider (SLC). We consider providing this e+ rate through a combination of measures: (1) Reducing the required production rate from the e+ target through colliding e+ (and the LHC protons) several times before deceleration, by reusing the e+ over several acceleration/deceleration cycles, and by cooling them, e.g., with a compact tri-ring scheme or a conventional damping ring in the SPS tunnel. (2) Using an advanced target, e.g., W-granules, rotating wheel, slicedrod converter, or liquid metal jet, for converting gamma rays to e+. (3) Selecting the most powerful of several proposed gamma sources, namely Compton ERL, Compton storage ring, coher...

Status of the SLC damping rings

International Nuclear Information System (INIS)

Hutton, A.M.; Davies-White, W.A.; Delahaye, J.P.

1985-06-01

Electron beams of full design energy 1.21 GeV and nearly full design intensity 4 x 10 10 particles/pulse (design 5 x 10 10 ) have been extracted from the Stanford Linac and successfully stored in the electron damping ring. Beams of less intensity have been extracted from the ring and reinjected into the Linac. The present intensity limits are not thought to be fundamental. The operating experience with the electron ring and the status of the construction of the positron ring will be discussed. 11 refs., 1 fig., 2 tabs

Localized chromaticity correction of low-beta insertions in storage rings

International Nuclear Information System (INIS)

Donald, M.; Helm, R.; Irwin, J.; Moshammer, H.; Sullivan, M.; Forest, E.; Robin, D.; Zholents, A.

1993-01-01

The correction of the chromaticity of low-beta insertions in the storage rings is usually made with sextupole lenses in the ring's arcs. When decreasing the beta functions at the insertion point (IP), this technique becomes fairly ineffective, since it fails to properly correct the higher order chromatic aberrations. Here the authors consider the approach where the chromatic effects of the quadrupole lenses generating low beta functions at the IP are corrected locally with two families of sextupoles, one family for each plane. Each family has two pairs of sextupoles which are located symmetrically on both sides of the IP. The sextupole-like aberrations of individual sextupoles are eliminated by utilizing optics forming a -I transformation between sextupoles in the pair. The optics also includes bending magnets which preserve equal dispersion functions at the two sextupoles in each pair. At sextupoles in one family, the vertical beta function is made large and the horizontal is made small. The situation is reversed in the sextupoles of the other family. The betatron phase advances from the IP to the sextupoles are chosen to eliminate a second order chromatic aberration. The application of the localized chromatic correction is demonstrated using as an example the lattice design for the Low Energy Ring of the SLAC/LBL/LLNL PEP-II B Factory

Localized chromaticity correction of low-beta insertions in storage rings

International Nuclear Information System (INIS)

Donald, M.; Helm, R.; Irwin, J.; Moshammer, H.; Sullivan, M.; Forest, E.; Robin, D.; Zholents, A.

1993-04-01

The correction of the chromaticity of low-beta insertions in the storage rings is usually made with sextupole lenses in the ring's arcs. When decreasing the beta functions at the insertion point (IP), this technique becomes fairly ineffective, since it fails to properly correct the higher order chromatic aberrations. Here we consider the approach where the chromatic effects of the quadrupole lenses generating low beta functions at the IP are corrected locally with two families of sextupoles, one family for each plane. Each family has two pairs of sextupoles which are located symmetrically on both sides of the IP. The sextupole-like aberrations of individual sextupoles are eliminated by utilizing optics forming a -I transformation between sextupoles in the pair. The optics also includes bending magnets which preserve equal dispersion functions at the two sextupoles in each pair. At sextupoles in one family, the vertical beta function is made large and the horizontal is made small. The situation is reversed in the sextupoles of the other family. The betatron phase advances from the IP to the sextupoles are chosen to eliminate a second order chromatic aberration. The application of the localized chromatic correction is demonstrated using as an example the lattice design for the Low Energy Ring of the SLAC/LBL/LLNL PEP-II B Factory

Ca 2+ signaling by plant Arabidopsis thaliana Pep peptides depends on AtPepR1, a receptor with guanylyl cyclase activity, and cGMP-activated Ca 2+ channels

KAUST Repository

Qia, Zhi

2010-11-18

A family of peptide signaling molecules (AtPeps) and their plasma membrane receptor AtPepR1 are known to act in pathogendefense signaling cascades in plants. Little is currently known about the molecular mechanisms that link these signaling peptides and their receptor, a leucine-rich repeat receptor-like kinase, to downstream pathogen-defense responses. We identify some cellular activities of these molecules that provide the context for a model for their action in signaling cascades. AtPeps activate plasma membrane inwardly conducting Ca 2+ permeable channels in mesophyll cells, resulting in cytosolic Ca 2+ elevation. This activity is dependent on their receptor as well as a cyclic nucleotide-gated channel (CNGC2). We also show that the leucine-rich repeat receptor- like kinase receptor AtPepR1 has guanylyl cyclase activity, generating cGMP from GTP, and that cGMP can activate CNGC2- dependent cytosolic Ca 2+ elevation. AtPep-dependent expression of pathogen-defense genes (PDF1.2, MPK3, and WRKY33) is mediated by the Ca 2+ signaling pathway associated with AtPep peptides and their receptor. The work presented here indicates that extracellular AtPeps, which can act as danger-associated molecular patterns, signal by interaction with their receptor, AtPepR1, a plasma membrane protein that can generate cGMP. Downstream from AtPep and AtPepR1 in a signaling cascade, the cGMP-activated channel CNGC2 is involved in AtPep- and AtPepR1-dependent inward Ca 2+ conductance and resulting cytosolic Ca 2+ elevation. The signaling cascade initiated by AtPeps leads to expression of pathogen- defense genes in a Ca 2+-dependent manner.

Status of PEP and TPC/2γ

International Nuclear Information System (INIS)

Zapalac, G.

1989-06-01

The TPC/2γ program at PEP has been upgraded by increasing the PEP luminosity and by the adding of a vertex chamber to the TPC detector. These improvements will allow a strong program in B and τ physics, and will contribute to ongoing studies in two-photon physics and hadronization. 10 refs., 3 figs

In vitro contraction of cytokinetic ring depends on myosin II but not on actin dynamics.

Science.gov (United States)

Mishra, Mithilesh; Kashiwazaki, Jun; Takagi, Tomoko; Srinivasan, Ramanujam; Huang, Yinyi; Balasubramanian, Mohan K; Mabuchi, Issei

2013-07-01

Cytokinesis in many eukaryotes involves the contraction of an actomyosin-based contractile ring. However, the detailed mechanism of contractile ring contraction is not fully understood. Here, we establish an experimental system to study contraction of the ring to completion in vitro. We show that the contractile ring of permeabilized fission yeast cells undergoes rapid contraction in an ATP- and myosin-II-dependent manner in the absence of other cytoplasmic constituents. Surprisingly, neither actin polymerization nor its disassembly is required for contraction of the contractile ring, although addition of exogenous actin-crosslinking proteins blocks ring contraction. Using contractile rings generated from fission yeast cytokinesis mutants, we show that not all proteins required for assembly of the ring are required for its contraction in vitro. Our work provides the beginnings of the definition of a minimal contraction-competent cytokinetic ring apparatus.

Circular-detector array hybrid emission computed tomograph, HEADTOME-II

Energy Technology Data Exchange (ETDEWEB)

Uemura, Kazuo; Kanno, Iwao; Miura, Yuko; Miura, Syuichi [Research Inst. of Brain and Blood Vessels, Akita (Japan); Hattori, Hiroyuki; Hirose, Yoshiharu; Nagata, Takashi; Higashi, Yoshihumi

1982-08-01

The HEADTOME-II is a successor of the original hybrid ECT, the HEADTOME-I, which was built and used in Research Institute of Brain and Blood Vessels, Akita. The new machine has three detector rings comprising 64 Nal crystals each, the axial length of which is 30 mm, 100 mm in total for three rings including 5 mm lead shield between the rings, and is long enough to examine most of the brain at a given time. The system sensitivity for positrons is 27.5 kcps/..mu..Ci/ml for intra-ring coincidence and 36.5 kcps for inter-ring coincidence. Spatial resolution is 10 mm FWHM at the center of the field of view. For single photon ECT study, new ''Turbofan'' rotating collimators, high sensitivity H.S. and high resolution H.R., are adopted. The collimators for single photons and positrons can be selected by manual operation. The system sensitivity for sup(99m)Tc is, 52.5 kcps/..mu..Ci/ml by H.S. and 13.8 kcps by H.R. collimator. Spatial resolution at the center of the field of view is 20 mm for H.S. and 11 mm for H.R. respectively. High quality images have been obtained by sup(99m)Tc, /sup 81/mKr, /sup 111/In and /sup 11/C. The regional cerebral blood flow study by /sup 133/Xe inhalation or intra-venous injection has been tried and good results are obtained.

Low emittance electron storage rings

Science.gov (United States)

Levichev, E. B.

2018-01-01

Low-emittance electron (positron) beams are essential for synchrotron light sources, linear collider damping rings, and circular Crab Waist colliders. In this review, the principles and methods of emittance minimization are discussed, prospects for developing relativistic electron storage rings with small beam phase volume are assessed, and problems related to emittance minimization are examined together with their possible solutions. The special features and engineering implementation aspects of various facilities are briefly reviewed.

Development of HyPEP, A Hydrogen Production Plant Efficiency Calculation Program

International Nuclear Information System (INIS)

Lee, Young Jin; Park, Ji Won; Lee, Won Jae; Shin, Young Joon; Kim, Jong Ho; Hong, Sung Deok; Lee, Seung Wook; Hwang, Moon Kyu

2007-12-01

Development of HyPEP program for assessing the steady-state hydrogen production efficiency of the nuclear hydrogen production facilities was carried out. The main developmental aims of the HyPEP program are the extensive application of the GUI for enhanced user friendliness and the fast numerical solution scheme. These features are suitable for such calculations as the optimisation calculations. HyPEP was developed with the object-oriented programming techniques. The components of the facility was modelled as objects in a hierarchical structure where the inheritance property of the object oriented program were extensively applied. The Delphi program language which is based on the Object Pascal was used for the HyPEP development. The conservation equations for the thermal hydraulic flow network were setup and the numerical solution scheme was developed and implemented into HyPEP beta version. HyPEP beta version has been developed with working GUI and the numerical solution scheme implementation. Due to the premature end of this project the fully working version of HyPEP was not produced

Longitudinal Stability Study for the FACET-II e⁺ Damping Ring

Energy Technology Data Exchange (ETDEWEB)

Bane, Karl [SLAC National Accelerator Lab., Menlo Park, CA (United States)

2016-11-29

This is an initial study of the longitudinal, single-bunch stability in the proposed FACET-II e⁺ damping ring. It is preliminary because, at present, only a few specific features of the vacuum chamber are known.

Positrons in biomolecular systems. II

International Nuclear Information System (INIS)

Glass, J.C.; Graf, G.; Costabal, H.; Ewert, D.H.; English, L.

1982-01-01

Pickoff-annihilation parameters, as related to the free volume model, are shown to be indicators of structural fluctuations in membranes and membrane bound proteins. Nitrous oxide anesthetic induces lateral rigidity in a membrane, and an anesthetic mechanism is suggested. Conformational changes of (Na + ,K + )ATPase in natural membrane are observed with ATP and Mg-ion binding. New positron applications to active transport and photosynthetic systems are suggested. (Auth.)

A circular-detector array hybrid emission computed tomograph, HEADTOME-II

International Nuclear Information System (INIS)

Uemura, Kazuo; Kanno, Iwao; Miura, Yuko; Miura, Syuichi; Hattori, Hiroyuki; Hirose, Yoshiharu; Nagata, Takashi; Higashi, Yoshihumi.

1982-01-01

The HEADTOME-II is a successor of the original hybrid ECT, the HEADTOME-I, which was built and used in Research Institute of Brain and Blood Vessels, Akita. The new machine has three detector rings comprising 64 Nal crystals each, the axial length of which is 30 mm, 100 mm in total for three rings including 5 mm lead shield between the rings, and is long enought to examine the most part of the brain at a time. The system sensitivity for positrons is 27.5 kcps/μCi/ml for intra-ring coincidence and 36.5 kcps for inter-ring coincidence. Spatial resolution is 10 mm FWHM at the center of the field of view. For single photon ECT study, new ''Turbofan'' rotaing collimators, high sensitivity H.S. and high resolution H.R., are adopted. The collimators for single photons and positrons can be selected by manual operation. The system sensitivity for sup(99m)Tc is, 52.5 kcps/μCi/ml by H.S. and 13.8 kcps by H.R. collimator. Spatial resolution at the center of the field of view is 20 mm for H.S. and 11 mm for H.R. respectively. High quality images have been obtained by sup(99m)Tc, 81 mKr, 111 In and 11 C. The regional cerebral blood flow study by 133 Xe inhalation or intra-venous injection has been tried and good results are obtained. (author)

Seepage into PEP tunnel

International Nuclear Information System (INIS)

Weidner, H.

1990-01-01

The current rate of seepage into the PEP tunnel in the vicinity of IR-10 is very low compared to previous years. Adequate means of handling this low flow are in place. It is not clear whether the reduction in the flow is temporary, perhaps due to three consecutive dry years, or permanent due to drainage of a perched water table. During PEP construction a large amount of effort was expended in attempts to seal the tunnel, with no immediate effect. The efforts to ''manage'' the water flow are deemed to be successful. By covering equipment to protect it from dripping water and channeling seepage into the drainage gutters, the seepage has been reduced to a tolerable nuisance. There is no sure, safe procedure for sealing a leaky shotcreted tunnel

Observation of Electron Cloud Instabilities and Emittance Dilution at the Cornell Electron-Positron Storage Ring Test Accelerator

International Nuclear Information System (INIS)

Holtzapple, R.L.; Campbell, R.C.; McArdle, K.E.; Miller, M.I.; Totten, M.M.; Tucker, S.L.; Billing, M.G.; Dugan, G.F.; Ramirez, G.A.; Sonnad, K.G.; Williams, H.A.; Flanagan, J.; Palmer, M.A.

2016-01-01

Electron cloud related emittance dilution and instabilities of bunch trains limit the performance of high intensity circular colliders. One of the key goals of the Cornell electron-positron storage ring Test Accelerator (CesrTA) research program is to improve our understanding of how the electron cloud alters the dynamics of bunches within the train. Single bunch beam diagnotics have been developed to measure the beam spectra, vertical beam size, two important dynamical effects of beams interacting with the electron cloud, for bunch trains on a turn-by-turn basis. Experiments have been performed at CesrTA to probe the interaction of the electron cloud with stored positron bunch trains. The purpose of these experiments was to characterize the dependence of beam-electron cloud interactions on the machine parameters such as bunch spacing, vertical chromaticity, and bunch current. The beam dynamics of the stored beam, in the presence of the electron cloud, was quantified using: 1) a gated beam position monitor (BPM) and spectrum analyzer to measure the bunch-by-bunch frequency spectrum of the bunch trains; 2) an x-ray beam size monitor to record the bunch-by-bunch, turn-by-turn vertical size of each bunch within the trains. In this paper we report on the observations from these experiments and analyze the effects of the electron cloud on the stability of bunches in a train under many different operational conditions

Design and construction of the Donner 280-crystal positron ring for dynamic transverse section emission imaging

International Nuclear Information System (INIS)

Derenzo, S.E.; Banchero, P.G.; Cahoon, J.L.; Huesman, R.H.; Vuletich, T.; Budinger, T.F.

1977-09-01

The design and construction of a medical imaging system for the rapid, accurate, three-dimensional imaging of positron-labeled compounds in the human body are described. Our medical research goals include quantifying blood flow and metabolism in human heart muscle and brain. The system consists of a large gantry containing lead shielding and a ring of 280 NaI(Tl) detectors that completely encircles the patient; 280 photomultiplier tubes, preamplifiers and timing discriminators; circuits that determine whenever a crystal has detected a gamma ray in time coincidence (i.e., within 12 nsec) of any of the opposing 105 crystals and determine the addresses of the crystals involved; 120K words of 12 bit memory for the simultaneous acquisition of data from eight portions of the cardiac cycle; and a hardwired image reconstructor capable of filtering and backprojecting data from 140 views to form a 210 x 210 computed transverse section image in less than 2 sec

Design and construction of the Donner 280-crystal positron ring for dynamic transverse section emission imaging

Energy Technology Data Exchange (ETDEWEB)

Derenzo, S.E.; Banchero, P.G.; Cahoon, J.L.; Huesman, R.H.; Vuletich, T.; Budinger, T.F.

1977-09-01

The design and construction of a medical imaging system for the rapid, accurate, three-dimensional imaging of positron-labeled compounds in the human body are described. Our medical research goals include quantifying blood flow and metabolism in human heart muscle and brain. The system consists of a large gantry containing lead shielding and a ring of 280 NaI(Tl) detectors that completely encircles the patient; 280 photomultiplier tubes, preamplifiers and timing discriminators; circuits that determine whenever a crystal has detected a gamma ray in time coincidence (i.e., within 12 nsec) of any of the opposing 105 crystals and determine the addresses of the crystals involved; 120K words of 12 bit memory for the simultaneous acquisition of data from eight portions of the cardiac cycle; and a hardwired image reconstructor capable of filtering and backprojecting data from 140 views to form a 210 x 210 computed transverse section image in less than 2 sec.

Saturn - lord of the rings. [Pioneer II investigation of Saturn reviewed

Energy Technology Data Exchange (ETDEWEB)

Hunt, G [University Coll., London (UK); Burgess, E

1979-12-13

Much new information has been obtained about Saturn and its system of rings by the spacecraft Pioneer II. One of the major discoveries was that Saturn has a magnetic field whose axis was found to correspond almost exactly with the axis of rotation of the planet. The planet was also found to be surrounded by belts of trapped energetic particles (radiation belts) which are effected by the planet's rings. It was not only discovered that Saturn has at least 10 satellites but also new information was provided by Pioneer about the Planet's ring system that would have been impossible to obtain from Earth-based observations. Analysis of Saturn's gravitational field, coupled with a temperature profile calculated from infrared measurements of the heat emitted by the clouds in excess of that received from the Sun, has allowed a new view of the interior of the planet to be developed.

StraPep: a structure database of bioactive peptides

Science.gov (United States)

Wang, Jian; Yin, Tailang; Xiao, Xuwen; He, Dan; Xue, Zhidong; Jiang, Xinnong; Wang, Yan

2018-01-01

Abstract Bioactive peptides, with a variety of biological activities and wide distribution in nature, have attracted great research interest in biological and medical fields, especially in pharmaceutical industry. The structural information of bioactive peptide is important for the development of peptide-based drugs. Many databases have been developed cataloguing bioactive peptides. However, to our knowledge, database dedicated to collect all the bioactive peptides with known structure is not available yet. Thus, we developed StraPep, a structure database of bioactive peptides. StraPep holds 3791 bioactive peptide structures, which belong to 1312 unique bioactive peptide sequences. About 905 out of 1312 (68%) bioactive peptides in StraPep contain disulfide bonds, which is significantly higher than that (21%) of PDB. Interestingly, 150 out of 616 (24%) bioactive peptides with three or more disulfide bonds form a structural motif known as cystine knot, which confers considerable structural stability on proteins and is an attractive scaffold for drug design. Detailed information of each peptide, including the experimental structure, the location of disulfide bonds, secondary structure, classification, post-translational modification and so on, has been provided. A wide range of user-friendly tools, such as browsing, sequence and structure-based searching and so on, has been incorporated into StraPep. We hope that this database will be helpful for the research community. Database URL: http://isyslab.info/StraPep PMID:29688386

Design and commissioning of the photon monitors and optical transport lines for the advanced photon source positron accumulator ring

International Nuclear Information System (INIS)

Berg, W.; Yang, B.; Lumpkin, A.; Jones, J.

1996-01-01

Two photon monitors have been designed and installed in the positron accumulator ring (PAR) of the Advanced Photon Source. The photon monitors characterize the beam's transverse profile, bunch length, emittance, and energy spread in a nonintrusive manner. An optical transport line delivers synchrotron light from the PAR out of a high radiation environment. Both charge-coupled device and fast-gated, intensified cameras are used to measure the transverse beam profile (0.11 - 1 mm for damped beam) with a resolution of 0.06 mm. A streak camera (θ τ =I ps) is used to measure the bunch length which is in the range of 0.3-1 ns. The design of the various transport components and commissioning results of the photon monitors will be discussed

Online beam energy measurement of Beijing electron positron collider II linear accelerator

Science.gov (United States)

Wang, S.; Iqbal, M.; Liu, R.; Chi, Y.

2016-02-01

This paper describes online beam energy measurement of Beijing Electron Positron Collider upgraded version II linear accelerator (linac) adequately. It presents the calculation formula, gives the error analysis in detail, discusses the realization in practice, and makes some verification. The method mentioned here measures the beam energy by acquiring the horizontal beam position with three beam position monitors (BPMs), which eliminates the effect of orbit fluctuation, and is much better than the one using the single BPM. The error analysis indicates that this online measurement has further potential usage such as a part of beam energy feedback system. The reliability of this method is also discussed and demonstrated in this paper.

Movable collimator for positron annihilation imaging device

International Nuclear Information System (INIS)

Thompson, C.J.

1981-01-01

A positron annihilation imaging device having two circular arrays of detectors disposed in spaced apart parallel planes wherein axially movable annular collimator rings are generally disposed in a pair of opposite planes outside the associated planes of the collimators to each collimator being movable toward the opposite collimator and a central collimator of annular configuration generally disposed between the two rows of detectors but being split into two rings which may be separated, the outer and inner collimators serving to enhance data readout and imaging

Dynamic positron emission tomography for study of cerebral hemodynamics in a cross section of the head using positron-emitting 68Ga-EDTA and 77Kr

International Nuclear Information System (INIS)

Yamamoto, Y.L.; Thompson, C.J.; Meyer, E.; Robertson, J.S.; Feindel, W.

1977-01-01

Dynamic positron emission tomographic studies were performed on over 120 patients with occlusive cerebrovascular disease, arteriovenous malformations, and brain tumors, using the positron section scanner, consisting of a ring of 32 scintillation detectors. The radiopharmaceuticals were nondiffusible 68 Ga-EDTA for transit time and uptake studies and the diffusible tracer, 77 Kr, for quantitative regional cerebral blood flow studies in every square centimeter of the cross section of the head. The results of dynamic positron emission tomography in correlation with the results from the gamma scintillation camera dynamic studies and computed tomography (CT) scans are discussed

High duty factor structures for e+e- storage rings

International Nuclear Information System (INIS)

Allen, M.A.; Karvonen, L.G.

1976-01-01

The next generation e + e - storage rings will need rf systems similar to those required for a continuous-duty linac of over 50 MeV. For the PEP Storage Ring at 18 GeV, it is presently planned to provide a peak accelerating voltage of 77 MV in 18 aluminum accelerating structures, each structure consisting of five slot-coupled cells operating in the π mode. Operating experience with the SPEAR five-cell structure is discussed. Power to each structure is provided by a 125-kW high-efficiency four-cavity klystron. No isolation has been used and the resulting interaction between the accelerating structures, klystrons and the stored beams is discussed

Simulation of the Beam-Beam Effects in e+e- Storage Rings with a Method of Reducing the Region of Mesh

Energy Technology Data Exchange (ETDEWEB)

Cai, Yunhai

2000-08-31

A highly accurate self-consistent particle code to simulate the beam-beam collision in e{sup +}e{sup -} storage rings has been developed. It adopts a method of solving the Poisson equation with an open boundary. The method consists of two steps: assigning the potential on a finite boundary using the Green's function, and then solving the potential inside the boundary with a fast Poisson solver. Since the solution of the Poisson's equation is unique, the authors solution is exactly the same as the one obtained by simply using the Green's function. The method allows us to select much smaller region of mesh and therefore increase the resolution of the solver. The better resolution makes more accurate the calculation of the dynamics in the core of the beams. The luminosity simulated with this method agrees quantitatively with the measurement for the PEP-II B-factory ring in the linear and nonlinear beam current regimes, demonstrating its predictive capability in detail.

Beam Dynamics Challenges for FCC-ee

CERN Document Server

AUTHOR|(SzGeCERN)442987; Benedikt, Michael; Oide, Katsunobu; Bogomyagkov, Anton; Levichev, Evgeny; Migliorati, Mauro; Wienands, Uli

2015-01-01

The goals of FCC-ee include reaching luminosities of up to a few 1036 cm-2s-1 per interaction point at the Z pole or some 1034 cm-2s-1 at the ZH production peak, and pushing the beam energy up to ≥175 GeV, in a ring of 100 km circumference, with a total synchrotron-radiation power not exceeding 100 MW. A parameter baseline as well as high-luminosity crab-waist options were described in [1] and [2], respectively. The extremely high luminosity and resulting short beam lifetime (due to radiative Bhabha scattering) are sustained by top-up injection. The FCC-ee design status and typical beam parameters for different modes of operation are reported in [3]. One distinct feature of the FCC-ee design is its conception as a double ring, with separate beam pipes for the two counter-rotating (electron and positron) beams, resembling, in this aspect, the high-luminosity B factories PEP-II, KEKB and SuperKEKB as well as the LHC. The two separate rings do not only permit operation with a large number of bunches, up to a f...

Post-Exposure Prophylaxis (PEP)

Science.gov (United States)

... Child Transmission of HIV Post-Exposure Prophylaxis (PEP) Pre-Exposure Prophylaxis (PrEP) HIV Treatment HIV Treatment: The Basics Just ... to HIV frequently. Another HIV prevention method, called pre-exposure prophylaxis or PrEP, is when people at high risk ...

Precision Measurement and Improvement of e+, e- Storage Rings

International Nuclear Information System (INIS)

Yan, Y.T.; Cai, Y.; Colocho, W.; Decker, F-J.; Seeman, J.; Sullivan, M.; Turner, J.; Wienands, U.; Woodley, M.; Yocky, G.

2006-01-01

Through horizontal and vertical excitations, we have been able to make a precision measurement of linear geometric optics parameters with a Model-Independent Analysis (MIA). We have also been able to build up a computer model that matches the real accelerator in linear geometric optics with an SVD-enhanced Least-square fitting process. Recently, with the addition of longitudinal excitation, we are able to build up a computer virtual machine that matches the real accelerators in linear optics including dispersion without additional fitting variables. With this optics-matched virtual machine, we are able to find solutions that make changes of selected normal and skew quadrupoles for machine optics improvement. It has made major contributions to improve PEP-II optics and luminosity. Examples from application to PEP-II machines will be presented

ZAP study of collective effects in PEP: 9 x 9 collider optics

International Nuclear Information System (INIS)

Corbett, W.J.

1990-02-01

In this note, single and multi-bunch collective instabilities are considered for PEP operating a 9 x 9 bunch configuration. The lattice is based on a vertically separated beam 'pretzel' design which allows for collisions at the TPC (IR2) only. Threshold current levels and linear instability growth rates are calculated with the storage ring design code 'ZAP'. Single bunch instabilities should not be a problem for total circulating currents of 100mA (18 bunches, 5.6mA/bunch). Coupled-bunch growth rate calculations are based on a line broadening technique for the higher-order cavity modes. In the longitudinal case, feedback will be required. For the transverse coupled bunch instabilities, growth rates are about 5 times less. 14 refs., 5 figs

Apiary B Factory lattice design

International Nuclear Information System (INIS)

Donald, M.H.R.; Garren, A.A.

1991-04-01

The Apiary B Factory is a proposed high-intensity electron-positron collider. This paper will present the lattice design for this facility, which envisions two rings with unequal energies in the PEP tunnel. The design has many interesting optical and geometrical features due to the needs to conform to the existing tunnel, and to achieve the necessary emittances, damping times and vacuum. Existing hardware is used to a maximum extent. 8 figs. 1 tab

Electron-positron annihilation at high luminosity colliding beams

International Nuclear Information System (INIS)

Grigoryan, G.V.; Khodzhamiryan, A.Yu.

1977-01-01

Experiments are discussed, which can be carried out at the electron-positron storage rings with increased luminosity (up to 10 34 cm -2 sec -1 ) and corresponding improvement of detectors at total energy region up to 10 GeV. This improvement of the experimental conditions may provide valuable physical information from the theoretical point of view. The comparison is made with analogous experimental possibilities of the projected high energy e + e - storage rings with luminosity up to 10 32 cm -2 sec -1

Effects of pergolide mesylate on transduction efficiency of PEP-1-catalase protein

International Nuclear Information System (INIS)

Sohn, Eun Jeong; Kim, Dae Won; Kim, Young Nam; Kim, So Mi; Lim, Soon Sung; Kang, Tae-Cheon; Kwon, Hyeok Yil; Kim, Duk-Soo; Cho, Sung-Woo; Han, Kyu Hyung; Park, Jinseu; Eum, Won Sik; Hwang, Hyun Sook; Choi, Soo Young

2011-01-01

Research highlights: → We studied effects of pergolide mesylate (PM) on in vitro and in vivo transduction of PEP-1-catalase. → PEP-1-catatase inhibited 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced inflammation. → PM enhanced the transduction of PEP-1-catalase into HaCaT cells and skin tissue. → PM increased anti-inflammatory activity of PEP-1-catalase. → PM stimulated therapeutic action of anti-oxidant enzyme catalase in oxidative-related diseases. -- Abstract: The low transduction efficiency of various proteins is an obstacle to their therapeutic application. However, protein transduction domains (PTDs) are well-known for a highly effective tool for exogenous protein delivery to cells. We examined the effects of pergolide mesylate (PM) on the transduction of PEP-1-catalase into HaCaT human keratinocytes and mice skin and on the anti-inflammatory activity of PEP-1-catatase against 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced inflammation using Western blot and histological analysis. PM enhanced the time- and dose-dependent transduction of PEP-1-catalase into HaCaT cells without affecting the cellular toxicity. In a mouse edema model, PEP-1-catalase inhibited the increased expressions of inflammatory mediators and cytokines such as cyclooxygenase-2, inducible nitric oxide synthase, interleukin-6 and -1β, and tumor necrosis factor-α induced by TPA. On the other hand, PM alone failed to exert any significant anti-inflammatory effects. However, the anti-inflammatory effect of co-treatment with PEP-1-catalase and PM was more potent than that of PEP-1-catalase alone. Our results indicate that PM may enhance the delivery of PTDs fusion therapeutic proteins to target cells and tissues and has potential to increase their therapeutic effects of such drugs against various diseases.

Effects of pergolide mesylate on transduction efficiency of PEP-1-catalase protein

Energy Technology Data Exchange (ETDEWEB)

Sohn, Eun Jeong; Kim, Dae Won; Kim, Young Nam; Kim, So Mi [Department of Biomedical Science and Research Institute of Bioscience and Biotechnology, Hallym University, Chunchon 200-702 (Korea, Republic of); Lim, Soon Sung [Department of Food Science and Nutrition and RIC Center, Hallym University, Chunchon 200-702 (Korea, Republic of); Kang, Tae-Cheon [Department of Anatomy and Neurobiology, College of Medicine, Hallym University, Chunchon 200-702 (Korea, Republic of); Kwon, Hyeok Yil [Department of Physiology, College of Medicine, Hallym University, Chunchon 200-702 (Korea, Republic of); Kim, Duk-Soo [Department of Anatomy, College of Medicine, Soonchunhyang University, Cheonan-Si 330-090 (Korea, Republic of); Cho, Sung-Woo [Department of Biochemistry and Molecular Biology, University of Ulsan College of Medicine, Seoul 138-736 (Korea, Republic of); Han, Kyu Hyung; Park, Jinseu; Eum, Won Sik [Department of Biomedical Science and Research Institute of Bioscience and Biotechnology, Hallym University, Chunchon 200-702 (Korea, Republic of); Hwang, Hyun Sook, E-mail: wazzup@hallym.ac.kr [Department of Biomedical Science and Research Institute of Bioscience and Biotechnology, Hallym University, Chunchon 200-702 (Korea, Republic of); Choi, Soo Young, E-mail: sychoi@hallym.ac.kr [Department of Biomedical Science and Research Institute of Bioscience and Biotechnology, Hallym University, Chunchon 200-702 (Korea, Republic of)

2011-03-18

Research highlights: {yields} We studied effects of pergolide mesylate (PM) on in vitro and in vivo transduction of PEP-1-catalase. {yields} PEP-1-catatase inhibited 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced inflammation. {yields} PM enhanced the transduction of PEP-1-catalase into HaCaT cells and skin tissue. {yields} PM increased anti-inflammatory activity of PEP-1-catalase. {yields} PM stimulated therapeutic action of anti-oxidant enzyme catalase in oxidative-related diseases. -- Abstract: The low transduction efficiency of various proteins is an obstacle to their therapeutic application. However, protein transduction domains (PTDs) are well-known for a highly effective tool for exogenous protein delivery to cells. We examined the effects of pergolide mesylate (PM) on the transduction of PEP-1-catalase into HaCaT human keratinocytes and mice skin and on the anti-inflammatory activity of PEP-1-catatase against 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced inflammation using Western blot and histological analysis. PM enhanced the time- and dose-dependent transduction of PEP-1-catalase into HaCaT cells without affecting the cellular toxicity. In a mouse edema model, PEP-1-catalase inhibited the increased expressions of inflammatory mediators and cytokines such as cyclooxygenase-2, inducible nitric oxide synthase, interleukin-6 and -1{beta}, and tumor necrosis factor-{alpha} induced by TPA. On the other hand, PM alone failed to exert any significant anti-inflammatory effects. However, the anti-inflammatory effect of co-treatment with PEP-1-catalase and PM was more potent than that of PEP-1-catalase alone. Our results indicate that PM may enhance the delivery of PTDs fusion therapeutic proteins to target cells and tissues and has potential to increase their therapeutic effects of such drugs against various diseases.

Microemulsion systems studied by positron annihilation techniques. II

International Nuclear Information System (INIS)

Lopez, R.; Olea, O.; Fucugauchi, L.A.

1982-01-01

The positron annihilation technique was applied to assess the effect of the double bond of the surfactant molecule on the microemulsion formation mechanism by replacing sodium stearate by sodium oleate in surfactant-cosurfactant-solvent-water systems. Diameters of microemulsions were measured by dynamic laser light scattering, and the obtained values concur with the present positron annihilation data. Structures of these microemulsions have been assessed by considering the available conformation and shapes of the surfactant-cosurfactant-solvent-assemblies. Volumes of the same aggregates have been calculated by taking into consideration the packing constraint imposed upon kink formation. (Auth.)

Initial-state-radiation production of D{sub s} Mesons and high precision measurements of D{sub s}1(2536) at Babar

Energy Technology Data Exchange (ETDEWEB)

Roney, Michael [Stanford Linear Accelerator Center - SLAC, National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025-7015 (United States); Izen, Joseph Michael [University of Texas at Dallas, Department of Physics, EC 36, 800 West Campbell Road, Richardson, Texas 75080-3021 (United States)

2010-07-01

A search for charmonium and other new states is performed in a study of exclusive initial-state-radiation production of D{sub s}{sup +}D{sub s}{sup -}, D{sub s}{sup *+}D{sub s}{sup -}, and D{sub s}{sup *+}D{sub s}{sup *-} events from electron-positron annihilations at a center-of-mass energy of 10.58 GeV. The data sample corresponds to an integrated luminosity of 525 fb{sup -1} recorded by the BaBar experiment at the PEP-II storage ring. We also study the decay width and the mass of the D{sub s}1(2536) meson with high precision via the decay channel D{sub s}1(2536){yields}D{sup +*} K{sup 0}{sub s} using 384 fb{sup -1} of data recorded by the BABAR experiment. (author)

Superconducting proton ring for PETRA

International Nuclear Information System (INIS)

Baynham, E.

1979-01-01

A powerful new facility for colliding beam physics could be provided by adding a proton storage ring in the range of several hundred GeV to the electron-positron storage ring PETRA at DESY. This can be achieved in an economic way utilizing the PETRA tunnel and taking advantage of the higher magnetic fields of superconducting magnets which would be placed above or below the PETRA magnets. A central field of 4 Tesla in the bending magnets corresponds to a proton energy of 225 GeV. (orig.)

A new liquid xenon scintillation detector for positron emission tomography

International Nuclear Information System (INIS)

Chepel, V.Yu.

1993-01-01

A new positron-sensitive detector of annihilation photons filled with liquid xenon is proposed for positron emission tomography. Simultaneous detection of both liquid xenon scintillation and ionization current produces a time resolution of < 1 ns and a position resolution in the tangential direction of the tomograph ring is ∼ 1 mm and in the radial direction is ∼ 5 mm. The advantages of a tomograph with new detectors are discussed. New algorithms of Compton scattering can be used. (author)

APS storage ring vacuum system performance

International Nuclear Information System (INIS)

Noonan, J.R.; Gagliano, J.; Goeppner, G.A.

1997-01-01

The Advanced Photon Source (APS) storage ring was designed to operated with 7-GeV, 100-mA positron beam with lifetimes > 20 hours. The lifetime is limited by residual gas scattering and Touschek scattering at this time. Photon-stimulated desorption and microwave power in the rf cavities are the main gas loads. Comparison of actual system gas loads and design calculations will be given. In addition, several special features of the storage ring vacuum system will be presented

PEP instrumentation and control system

Energy Technology Data Exchange (ETDEWEB)

Melen, R.

1980-06-01

This paper describes the operating characteristics of the primary components that form the PEP Instrumentation and Control System. Descriptions are provided for the computer control system, beam monitors, and other support systems.

PEP instrumentation and control system

International Nuclear Information System (INIS)

Melen, R.

1980-06-01

This paper describes the operating characteristics of the primary components that form the PEP Instrumentation and Control System. Descriptions are provided for the computer control system, beam monitors, and other support systems

Lattice design for the CEPC double ring scheme

Science.gov (United States)

Wang, Yiwei; Su, Feng; Bai, Sha; Zhang, Yuan; Bian, Tianjian; Wang, Dou; Yu, Chenghui; Gao, Jie

2018-01-01

A future Circular Electron Positron Collider (CEPC) has been proposed by China with the main goal of studying the Higgs boson. Its baseline design, chosen on the basis of its performance, is a double ring scheme; an alternative design is a partial double ring scheme which reduces the budget while maintaining an adequate performance. This paper will present the collider ring lattice design for the double ring scheme. The CEPC will also work as a W and a Z factory. For the W and Z modes, except in the RF region, compatible lattices were obtained by scaling down the magnet strength with energy.

Modeling and Simulation of the Longitudinal Beam Dynamics - RF Station Interaction in the LHC Rings

International Nuclear Information System (INIS)

Mastorides, T

2008-01-01

A non-linear time-domain simulation has been developed to study the interaction between longitudinal beam dynamics and RF stations in the LHC rings. The motivation for this tool is to determine optimal LLRF configurations, to study system sensitivity on various parameters, and to define the operational and technology limits. It will be also used to study the effect of RF station noise, impedance, and perturbations on the beam life time and longitudinal emittance. It allows the study of alternative LLRF implementations and control algorithms. The insight and experience gained from our PEP-II simulation is important for this work. In this paper we discuss properties of the simulation tool that will be helpful in analyzing the LHC RF system and its initial results. Partial verification of the model with data taken during the LHC RF station commissioning is presented

Observation of the undulator radiation from the positron beam

International Nuclear Information System (INIS)

Maezawa, Hideki.

1986-02-01

A spectral measurement of the 1st harmonic of the undulator radiation emitted from positron beam was made on Dec. 21, 1985 during a test operation of the Photon Factory storage ring with the 2.5 GeV positron beam which was stored up to 5.5 mA. In comparison to the same measurement performed with the electron beam, no appreciable difference in the spectral properties of the undulator radiation was found between the two cases under the condition of the low beam current of a few mA. (author)

Knowledge, Attitude and Practice of Post-Exposure Prophylaxis (PEP)

African Journals Online (AJOL)

user

Their levels of knowledge and indications for. PEP as well as ... uninfected patient and even re-infection of an already infected .... Surgical cuts/wounds. 7 ... Table 4: Knowledge of time of administration of PEP. Time .... respondents to be uncertain about the existence of such ... Surely, before the advent of this long awaited.

Positron annihilation imaging device having movable collimator

International Nuclear Information System (INIS)

Thompson, C.J.

1981-01-01

This patent application relates to a positron annihilation imaging device comprising two circular arrays of detectors disposed in spaced apart parallel planes and circumferentially offset by half the detector spacing, axially movable annular outer collimator rings, generally disposed in a pair of opposite planes outside the associated planes of the detectors, each collimator being movable toward the opposite collimator. An inner collimator of annular configuration is disposed between the two rows of detectors and is formed in two rings which may be separated axially. The outer and inner collimators serve to enhance data readout and imaging. (author)

A missing-bending-magnet scheme for PEP

International Nuclear Information System (INIS)

Liu, R.Z.; Winick, H.

1988-01-01

This article presents a missing-bending-magnet scheme for PEP as a modification that could be considered if PEP were available as a fully dedicated synchrotron radiation source. The scheme can be applied to one or more PEP sextants without changing the rest. By removing some bending magnets, rearranging the remaining magnets, and adding two quadrupoles, ten additional straight sections per sextant can be created, each 5 m or more in length, for insertion devices. Beam lines therefrom, plus possible beam lines from bending magnets would enter a continuous experimental hall instead of individual tunnels and halls for each beam line. This should result in construction cost savings and increased operations efficiency. The ideal beam orbit is unchanged at the two ends and the middle of the sextant. At the end of the curved part of the sextant the lattice functions match those of the long interaction region straight section in the low emittance configuration of PEP. The electron beam characteristics in the newly created straight sections are described, including the enlargement of the horizontal beam size due to the nonzero dispersion. Some disadvantages of the scheme are increased operations complexity due to the need for nine new quadrupole families, increased beam emittance (by 14.5% is one sextant is modified), and reduced dynamic aperture. However, the dynamic aperture is still about as large as the physical aperture and should be adequate for good beam lifetime and injection. (orig.)

Beam dynamics in Compton ring gamma sources

Directory of Open Access Journals (Sweden)

Eugene Bulyak

2006-09-01

Full Text Available Electron storage rings of GeV energy with laser pulse stacking cavities are promising intense sources of polarized hard photons which, via pair production, can be used to generate polarized positron beams. In this paper, the dynamics of electron bunches circulating in a storage ring and interacting with high-power laser pulses is studied both analytically and by simulation. Both the common features and the differences in the behavior of bunches interacting with an extremely high power laser pulse and with a moderate pulse are discussed. Also considerations on particular lattice designs for Compton gamma rings are presented.

The ring-stiffened shell of the ISAR II nuclear power plant natural-draught cooling tower

International Nuclear Information System (INIS)

Form, J.

1986-01-01

The natural-draught cooling tower of the ISAR II nuclear power plant is one of the largest in the world. The bid specifications provided for an unstiffened cooling tower shell. For the execution, however, it was decided to adopt a shell with three additional stiffening rings. The present contribution deals with the static and dynamic calculations of the execution and, in particular, with the working technique employed for the construction of the rings. (author)

Study on grown-in defects in CZ-Si by positron annihilation

International Nuclear Information System (INIS)

Nakagawa, S.; Hori, F.; Oshima, R.

2004-01-01

In order to study the nature of grown-in microdefects of a silicon wafer taken from a czochralski-grown single crystal (CZ-Si) in which ring oxidation-induced stacking faults (ring-OSF) are formed after oxidation heat treatment, positron annihilation coincidence Doppler broadening experiments (CDB) have been performed. Vacancy-type defects were detected in the central region of a wafer of an as-grown crystal, and they were changed with annealing. It was confirmed that different types of defects were formed in the regions of outside and inside of the ring-OSF. (orig.)

Positron annihilation imaging device using multiple offset rings of detectors

International Nuclear Information System (INIS)

Thompson, C.J.

1981-01-01

This patent application relates to a positron annihilation imaging device comprising two or more coaxial circular arrays of detectors (2,2'), with the detectors in one array angularly offset with respect to the detectors in the adjacent array to detect more than one tomographic image simultaneously through different cross-sections of a patient. (author)

Calculation of the detection efficiency in liquid scintillators. II. Single positron emitters

International Nuclear Information System (INIS)

Grau Malonda, A.; Garcia Torano, E.

1982-01-01

Counting efficiency as a function of the figure of merit for 30 positron emitters has been computed from the positron energy spectrum. Only the efficiency contribution of positrons has been taken into consideration. The contribution of the annihilation photons depending on the volume of the scintillator will be investigated in a near future. Efficiency vs figure of merit is plotted and tabulated. (Author) 19 refs

Development of positron emitting radionuclides for imaging with improved positron detectors

International Nuclear Information System (INIS)

Yano, Y.

1976-10-01

Recent advances in positron cameras and positron ring detectors for transverse section reconstruction have created renewed interest in positron emitting radionuclides. This paper reports on: generator-produced 82 Rb; cyclotron-produced 62 Zn; and reactor-produced 64 Cu. Investigation of the 82 Sr (25 d)-- 82 Rb (75 s) generator determined the elution characteristics for Bio-Rex 70, a weakly acidic carboxylic cation exchanger, using 2% NaCl as the eluent. The yield of 82 Rb and the breakthrough of 82 Sr were determined for newly prepared columns and for long term elution conditions. Spallation-produced 82 Sr was used to charge a compact 82 Rb generator to obtain multi-millicurie amounts of 82 Rb for myocardial imaging. Zinc accumulates in the islet cells of the pancreas and in the prostate. Zinc-62 was produced by protons on Cu foil and separated by column chromatography. Zinc-62 was administered as the amino acid chelates and as the ZnCl 2 to tumor and normal animals. Tissue distribution was determined for various times after intravenous injection. Pancreas-liver images of 62 Zn-histidine uptake were obtained in animals with the gamma camera and the liver uptake of /sup 99m/Tc sulfur colloid was computer subtracted to image the pancreas alone. The positron camera imaged uptake of 62 Zn-histidine in the prostate of a dog at 20 h. 64 Cu was chelated to asparagine, a requirement of leukemic cells, and administered to lymphoma mice. Uptake in tumor and various tissues was determined and compared with the uptake of 67 Ga citrate under the same conditions. 64 Cu-asparagine had better tumor-to-soft tissue ratios than 67 Ga-citrate

Precision surveying system for PEP

International Nuclear Information System (INIS)

Gunn, J.; Lauritzen, T.; Sah, R.; Pellisier, P.F.

1977-01-01

A semi-automatic precision surveying system is being developed for PEP. Reference elevations for vertical alignment will be provided by a liquid level. The short range surveying will be accomplished using a Laser Surveying System featuring automatic data acquisition and analysis

Transverse instability excited by rf deflecting modes for PEP

International Nuclear Information System (INIS)

Chao, A.W.; Yao, C.Y.

1979-11-01

We have looked at the possible transverse instability effects which are caused by the deflecting modes of the rf cavities in PEP. The results are obtained by applying the expression of the instability damping rate. We have assumed that there equal bunches equally spaced in PEP. We have worked out the equivalent for a single bunch beam. The effect of chromaticity ξ is included as a frequency shift in the bunch mode spectra. We rewrite this result in terms of the transverse wake field instead of the impedance. We include an application of the Sacherer formalism to the case of resistive wall. The resulting expression of the damping rate contains two terms. The first term corresponds to the effect of the short wake fields; it agrees with the result of the head-tail instability as derived by Sands. A numerical estimate of this resistive-wall head tail case for PEP is given. It re-confirms that the resistive wall instability is not a serious problem for PEP. The second term gives the effect of long wake fields and it agrees with the result of Courant and Sessler. 10 refs., 2 figs

The Woods Hole Partnership Education Program (PEP): Broadening Participation in the Geosciences

Science.gov (United States)

Scott, O.; Jearld, A., Jr.; Liles, G.; Gutierrez, B.

2015-12-01

In March 2009, the Woods Hole Diversity Initiative launched the Partnership Education Program (PEP), a multi-institutional effort to increase diversity in the student population (and ultimately the work force) in the Woods Hole science community. PEP, a summer research internship program, is open to students of all backgrounds but is designed especially to provide opportunities for URM in science, technology, engineering, and mathematics (STEM). PEP is a 10-week program which provides intensive mentored research, a credit-bearing course and supplemental career and professional development activities. Students have opportunities to work in various research areas of geosciences. PEP is emerging as an effective and sustainable approach to bringing students into the STEM research community. PEP is carefully structured to provide critical support for students as they complete their undergraduate experience and prepare for geosciences careers and/or graduate school. The PEP experience is intended to provide students with an entry into the Woods Hole science community, one of the most vibrant marine and environmental research communities in the world. The program aims to provide a first-hand introduction to emerging issues and real-world training in the research skills that students need to advance in science, either as graduate students or bachelors-level working scientists. This is a long-recognized need and efforts are being made to ensure that the students begin to acquire skills and aptitudes that position them to take advantage of a wide range of opportunities. Of note is that the PEP is transitioning into a two year program where students are participating in a second year as a research intern or employee. Since 2013, at least four partner institutions have invited PEP alumni to participate in their respective programs as research assistants and/or full-time technicians.

PEP radiation shielding tests in SLAC A Beam

International Nuclear Information System (INIS)

Ash, W.; DeStaebler, H.; Harris, J.; Jenkins, T.; Murray, J.

1977-09-01

Radiation shielding tests designed to simulate possible conditions in and around the PEP experimental halls were conducted. The SLAC A Beam was targeted in the block tunnel at a point about midway between End Station A and Beam Dump East. At that site it was relatively easy to rearrange the concrete block structure to simulate the various shielding configurations under consideration for PEP. Extensive surveys of neutron and ionizing radiation were made. Complete results of the shielding tests are given

Components for the CERN LEP ring

Energy Technology Data Exchange (ETDEWEB)

1987-01-01

One of the most important experimental setups at the LEP (Large Electron Positron Collider) ring is called OPAL (Omni Purpose Apparatus for LEP). Sulzer-Escher Wyss, Zurich, is to deliver the iron yoke, i.e. the mechanical part of one of the nine OPAL detectors. The contract for the yoke includes essentially the two side parts, each consisting of ten modules and two end caps, the middle part, four special modules and two supporting rings, as well as both the poles. The combined weight of all the supply items comes to some 2300 t. (Auth.).

Preschool Children's Performance on Profiling Elements of Prosody in Speech-Communication (PEPS-C)

Science.gov (United States)

Gibbon, Fiona E.; Smyth, Heather

2013-01-01

Profiling Elements of Prosody in Speech-Communication (PEPS-C) has not been used widely to assess prosodic abilities of preschool children. This study was therefore aimed at investigating typically developing 4-year-olds' performance on PEPS-C. PEPS-C was presented to 30 typically developing 4-year-olds recruited in southern Ireland. Children were…

Factors Associated With Forensic Nurses Offering HIV nPEP Status Post Sexual Assault.

Science.gov (United States)

Draughon, Jessica E; Hauda, William E; Price, Bonnie; Rotolo, Sue; Austin, Kim Wieczorek; Sheridan, Daniel J

2015-09-01

Nonoccupational, postexposure prophylaxis (nPEP) for human immunodeficiency virus (HIV) is offered inconsistently to patients who have been sexually assaulted. This may be due to Forensic Nurse Examiner (FNE) programs utilizing diverse nPEP protocols and HIV risk assessment algorithms. This study examines factors associated with FNEs offering nPEP to patients following sexual assault at two FNE programs in urban settings. Offering nPEP is mostly driven by site-specific protocol. At Site 1, in addition to open anal or open genital wounds, the presence of injury to the head or face was associated with FNEs offering nPEP (adjusted odds ratio [AOR] 64.15, 95% confidence interval [CI] = [2.12, 1942.37]). At Site 2, patients assaulted by someone of Other race/ethnicity (non-White, non-African American) were 86% less likely to be offered nPEP (AOR 0.14, 95% CI = [.03, .72]) than patients assaulted by Whites. In addition to following site-specific protocols, future research should further explore the mechanisms influencing clinician decision making. © The Author(s) 2014.

Antideuteron production in Upsilon(nS) decays and in e(+)e(-) -> q(q) over bar at root s approximate to 10.58 GeV

NARCIS (Netherlands)

Lees, J. P.; Poireau, V.; Tisserand, V.; Grauges, E.; Palano, A.; Eigen, G.; Stugu, B.; Brown, D. N.; Kerth, L. T.; Kolomensky, Yu. G.; Lynch, G.; Schroeder, T.; Hearty, C.; Mattison, T. S.; McKenna, J. A.; So, R. Y.; Khan, A.; Blinov, V. E.; Buzykaev, A. R.; Druzhinin, V. P.; Golubev, V. B.; Kravchenko, E. A.; Onuchin, A. P.; Serednyakov, S. I.; Skovpen, Yu. I.; Solodov, E. P.; Todyshev, K. Yu.; Lankford, A. J.; Mandelkern, M.; Dey, B.; Gary, J. W.; Long, O.; Campagnari, C.; Sevilla, M. Franco; Hong, T. M.; Kovalskyi, D.; Richman, J. D.; West, C. A.; Eisner, A. M.; Lockman, W. S.; Vazquez, W. Panduro; Schumm, B. A.; Seiden, A.; Chao, D. S.; Echenard, B.; Flood, K. T.; Hitlin, D. G.; Miyashita, T. S.; Ongmongkolkul, P.; Andreassen, R.; Huard, Z.; Meadows, B. T.; Pushpawela, B. G.; Sokoloff, M. D.; Sun, L.; Bloom, P. C.; Ford, W. T.; Gaz, A.; Smith, J. G.; Wagner, S. R.; Ayad, R.; Toki, W. H.; Spaan, B.; Bernard, D.; Verderi, M.; Playfer, S.; Bettoni, D.; Bozzi, C.; Calabrese, R.; Cibinetto, G.; Fioravanti, E.; Garzia, I.; Luppi, E.; Piemontese, L.; Santoro, V.; Calcaterra, A.; de Sangro, R.; Finocchiaro, G.; Martellotti, S.; Patteri, P.; Peruzzi, I. M.; Piccolo, M.; Rama, M.; Zallo, A.; Contri, R.; Lo Vetere, M.; Monge, M. R.; Passaggio, S.; Patrignani, C.; Robutti, E.; Bhuyan, B.; Prasad, V.; Morii, M.; Adametz, A.; Uwer, U.; Lacker, H. M.; Dauncey, P. D.; Mallik, U.; Cochran, J.; Prell, S.; Ahmed, H.; Gritsan, A. V.; Arnaud, N.; Davier, M.; Derkach, D.; Grosdidier, G.; Le Diberder, F.; Lutz, A. M.; Malaescu, B.; Roudeau, P.; Stocchi, A.; Wormser, G.; Lange, D. J.; Wright, D. M.; Coleman, J. P.; Fry, J. R.; Gabathuler, E.; Hutchcroft, D. E.; Payne, D. J.; Touramanis, C.; Bevan, A. J.; Di Lodovico, F.; Sacco, R.; Cowan, G.; Bougher, J.; Brown, D. N.; Davis, C. L.; Denig, A. G.; Fritsch, M.; Gradl, W.; Griessinger, K.; Hafner, A.; Prencipe, E.; Schubert, K. R.; Barlow, R. J.; Lafferty, G. D.; Cenci, R.; Hamilton, B.; Jawahery, A.; Roberts, D. A.; Cowan, R.; Sciolla, G.; Cheaib, R.; Patel, P. M.; Robertson, S. H.; Neri, N.; Palombo, F.; Cremaldi, L.; Godang, R.; Sonnek, P.; Summers, D. J.; Simard, M.; Taras, P.; De Nardo, G.; Onorato, G.; Sciacca, C.; Martinelli, M.; Raven, G.; Jessop, C. P.; LoSecco, J. M.; Honscheid, K.; Kass, R.; Feltresi, E.; Margoni, M.; Morandin, M.; Posocco, M.; Rotondo, M.; Simi, G.; Simonetto, F.; Stroili, R.; Akar, S.; Ben-Haim, E.; Bomben, M.; Bonneaud, G. R.; Briand, H.; Calderini, G.; Chauveau, J.; Leruste, Ph.; Marchiori, G.; Ocariz, J.; Sitt, S.; Biasini, M.; Manoni, E.; Pacetti, S.; Rossi, A.; Angelini, C.; Batignani, G.; Bettarini, S.; Carpinelli, M.; Casarosa, G.; Cervelli, A.; Chrzaszcz, M.; Forti, F.; Giorgi, M. A.; Lusiani, A.; Oberhof, B.; Paoloni, E.; Perez, A.; Rizzo, G.; Walsh, J. J.; Pegna, D. Lopes; Olsen, J.; Smith, A. J. S.; Faccini, R.; Ferrarotto, F.; Ferroni, F.; Gaspero, M.; Gioi, L. Li; Piredda, G.; Buenger, C.; Dittrich, S.; Gruenberg, O.; Leddig, T.; Voss, C.; Waldi, R.; Adye, T.; Olaiya, E. O.; Wilson, F. F.; Emery, S.; Vasseur, G.; Anulli, F.; Aston, D.; Bard, D. J.; Cartaro, C.; Convery, M. R.; Dorfan, J.; Dubois-Felsmann, G. P.; Dunwoodie, W.; Ebert, M.; Field, R. C.; Fulsom, B. G.; Graham, M. T.; Hast, C.; Innes, W. R.; Kim, P.; Leith, D. W. G. S.; Lewis, P.; Lindemann, D.; Luitz, S.; Luth, V.; Lynch, H. L.; MacFarlane, D. B.; Muller, D. R.; Neal, H.; Perl, M.; Pulliam, T.; Ratcliff, B. N.; Roodman, A.; Salnikov, A. A.; Schindler, R. H.; Snyder, A.; Su, D.; Sullivan, M. K.; Va'vra, J.; Wisniewski, W. J.; Wulsin, H. W.; Purohit, M. V.; White, R. M.; Wilson, J. R.; Randle-Conde, A.; Sekula, S. J.; Bellis, M.; Burchat, P. R.; Puccio, E. M. T.; Alam, M. S.; Ernst, J. A.; Gorodeisky, R.; Guttman, N.; Peimer, D. R.; Soffer, A.; Spanier, S. M.; Ritchie, J. L.; Ruland, A. M.; Schwitters, R. F.; Wray, B. C.; Izen, J. M.; Lou, X. C.; Bianchi, F.; De Mori, F.; Filippi, A.; Gamba, D.; Lanceri, L.; Vitale, L.; Martinez-Vidal, F.; Oyanguren, A.; Villanueva-Perez, P.; Albert, J.; Banerjee, Sw.; Beaulieu, A.; Bernlochner, F. U.; Choi, H. H. F.; Kowalewski, R.; Lewczuk, M. J.; Lueck, T.; Nugent, I. M.; Roney, J. M.; Sobie, R. J.; Tasneem, N.; Gershon, T. J.; Harrison, P. F.; Latham, T. E.; Band, H. R.; Dasu, S.; Pan, Y.; Prepost, R.

2014-01-01

We present measurements of the inclusive production of antideuterons in e+e− annihilation into hadrons at ≈10.58  GeV center-of-mass energy and in Υ(1S,2S,3S) decays. The results are obtained using data collected by the BABAR detector at the PEP-II electron-positron collider. Assuming a fireball

Photocapacitance study of type-II GaSb/GaAs quantum ring solar cells

Energy Technology Data Exchange (ETDEWEB)

Wagener, M. C.; Botha, J. R. [Department of Physics, Nelson Mandela Metropolitan University, Port Elizabeth (South Africa); Carrington, P. J.; Krier, A. [Department of Physics, Lancaster University, Lancaster LA1 4YB (United Kingdom)

2014-01-07

In this study, the density of states associated with the localization of holes in GaSb/GaAs quantum rings are determined by the energy selective charging of the quantum ring distribution. The authors show, using conventional photocapacitance measurements, that the excess charge accumulated within the type-II nanostructures increases with increasing excitation energies for photon energies above 0.9 eV. Optical excitation between the localized hole states and the conduction band is therefore not limited to the Γ(k = 0) point, with pseudo-monochromatic light charging all states lying within the photon energy selected. The energy distribution of the quantum ring states could consequently be accurately related from the excitation dependence of the integrated photocapacitance. The resulting band of localized hole states is shown to be well described by a narrow distribution centered 407 meV above the GaAs valence band maximum.

Isolation and characterization of PEP3, a gene required for vacuolar biogenesis in Saccharomyces cerevisiae.

OpenAIRE

Preston, R A; Manolson, M F; Becherer, K; Weidenhammer, E; Kirkpatrick, D; Wright, R; Jones, E W

1991-01-01

The Saccharomyces cerevisiae PEP3 gene was cloned from a wild-type genomic library by complementation of the carboxypeptidase Y deficiency in a pep3-12 strain. Subclone complementation results localized the PEP3 gene to a 3.8-kb DNA fragment. The DNA sequence of the fragment was determined; a 2,754-bp open reading frame predicts that the PEP3 gene product is a hydrophilic, 107-kDa protein that has no significant similarity to any known protein. The PEP3 predicted protein has a zinc finger (CX...

Improved positron emission tomography camera

International Nuclear Information System (INIS)

Mullani, N.A.

1986-01-01

A positron emission tomography camera having a plurality of rings of detectors positioned side-by-side or offset by one-half of the detector cross section around a patient area to detect radiation therefrom, and a plurality of scintillation crystals positioned relative to the photomultiplier tubes whereby each tube is responsive to more than one crystal. Each alternate crystal in the ring may be offset by one-half or less of the thickness of the crystal such that the staggered crystals are seen by more than one photomultiplier tube. This sharing of crystals and photomultiplier tubes allows identification of the staggered crystal and the use of smaller detectors shared by larger photomultiplier tubes thereby requiring less photomultiplier tubes, creating more scanning slices, providing better data sampling, and reducing the cost of the camera. (author)

The Ustilago maydis effector Pep1 suppresses plant immunity by inhibition of host peroxidase activity.

Directory of Open Access Journals (Sweden)

Christoph Hemetsberger

Full Text Available The corn smut Ustilago maydis establishes a biotrophic interaction with its host plant maize. This interaction requires efficient suppression of plant immune responses, which is attributed to secreted effector proteins. Previously we identified Pep1 (Protein essential during penetration-1 as a secreted effector with an essential role for U. maydis virulence. pep1 deletion mutants induce strong defense responses leading to an early block in pathogenic development of the fungus. Using cytological and functional assays we show that Pep1 functions as an inhibitor of plant peroxidases. At sites of Δpep1 mutant penetrations, H₂O₂ strongly accumulated in the cell walls, coinciding with a transcriptional induction of the secreted maize peroxidase POX12. Pep1 protein effectively inhibited the peroxidase driven oxidative burst and thereby suppresses the early immune responses of maize. Moreover, Pep1 directly inhibits peroxidases in vitro in a concentration-dependent manner. Using fluorescence complementation assays, we observed a direct interaction of Pep1 and the maize peroxidase POX12 in vivo. Functional relevance of this interaction was demonstrated by partial complementation of the Δpep1 mutant defect by virus induced gene silencing of maize POX12. We conclude that Pep1 acts as a potent suppressor of early plant defenses by inhibition of peroxidase activity. Thus, it represents a novel strategy for establishing a biotrophic interaction.

Storage ring design of the 8 GeV synchrotron radiation facility (SPring-8)

International Nuclear Information System (INIS)

Hara, M.; Bc, S.H.; Motonaga, S.

1990-01-01

In Japan, RIKEN (Institute of Physical and Chemical Research) and JAERI (Japan Atomic Energy Research Institute) have organized a joint design team and started a design study for an 8 GeV synchrotron radiation X-ray source. This paper outlines the status of the design study for the 8 GeV highly brilliant synchrotron radiation X-ray source ring named Super Photon Ring (SPring-8). The facility consists of a main storage ring, a full-energy injector booster synchrotron and a pre-injector 1 GeV linac. The injector linac and synchrotron are laid outside the storage ring because to permit the use of the linac and synchrotron not only as an injector but also as an electron or positron beam source. The purpose of the facility is to provide stable photon beams with high brilliance in the X-ray region. The energy of the stored electrons (positrons) is fixed at 8 GeV to fulfill the required condition using conventional type insertion devices. (N.K.)

PEP Run Report for Simulant Shakedown/Functional Testing

Energy Technology Data Exchange (ETDEWEB)

Josephson, Gary B.; Geeting, John GH; Bredt, Ofelia P.; Burns, Carolyn A.; Golovich, Elizabeth C.; Guzman-Leong, Consuelo E.; Kurath, Dean E.; Sevigny, Gary J.

2009-12-29

Pacific Northwest National Laboratory (PNNL) has been tasked by Bechtel National Inc. (BNI) on the River Protection Project-Waste Treatment Plant (RPP-WTP) project to perform research and development activities to resolve technical issues identified for the Pretreatment Facility (PTF). The Pretreatment Engineering Platform (PEP) was designed, constructed, and operated as part of a plan to respond to issue M12, "Undemonstrated Leaching Processes." The PEP is a 1/4.5-scale test platform designed to simulate the WTP pretreatment caustic leaching, oxidative leaching, ultrafiltration solids concentration, and slurry washing processes. The PEP replicates the WTP leaching processes using prototypic equipment and control strategies. The PEP also includes non-prototypic ancillary equipment to support the core processing. Two operating scenarios are currently being evaluated for the ultrafiltration process (UFP) and leaching operations. The first scenario has caustic leaching performed in the UFP-2 ultrafiltration feed vessels (i.e., vessel UFP-VSL-T02A in the PEP; and vessels UFP-VSL-00002A and B in the WTP PTF). The second scenario has caustic leaching conducted in the UFP-1 ultrafiltration feed preparation vessels (i.e., vessels UFP-VSL-T01A and B in the PEP; vessels UFP-VSL-00001A and B in the WTP PTF). In both scenarios, 19-M sodium hydroxide solution (NaOH, caustic) is added to the waste slurry in the vessels to leach solid aluminum compounds (e.g., gibbsite, boehmite). Caustic addition is followed by a heating step that uses direct injection of steam to accelerate the leach process. Following the caustic leach, the vessel contents are cooled using vessel cooling jackets and/or external heat exchangers. The main difference between the two scenarios is that for leaching in UFP-1, the 19-M NaOH is added to un-concentrated waste slurry (3-8 wt% solids), while for leaching in UFP-2, the slurry is concentrated to nominally 20 wt% solids using cross-flow ultrafiltration

Optical beam diagnostics on PEP

International Nuclear Information System (INIS)

Sabersky, A.P.

1981-02-01

In designing the PEP optical diagnostics we have been able to build on the experience gained with SPEAR. Most of the problems at SPEAR could be traced to the optical diagnostic system being inside the tunnel. A machine shutdown is required for any maintenance or modification. This implies that in order to make such an instrument successful, a large engineering effort must be mounted to ensure 100% operation at startup. The functions that do not work at startup may never be made to work; this has happened at several machines. Experimental setups are likewise risky and time consuming. A point which has been borne out in both SPEAR and PEP is that the mechanical part of the instrument, the special vacuum chamber, the optical mounts, the alignment and adjustments, require approximately 60% of the effort and cost of the optical diagnostics. It is far better to economize on detectors and electronics than on mechanical and optical essentials

DomPep--a general method for predicting modular domain-mediated protein-protein interactions.

Directory of Open Access Journals (Sweden)

Lei Li

Full Text Available Protein-protein interactions (PPIs are frequently mediated by the binding of a modular domain in one protein to a short, linear peptide motif in its partner. The advent of proteomic methods such as peptide and protein arrays has led to the accumulation of a wealth of interaction data for modular interaction domains. Although several computational programs have been developed to predict modular domain-mediated PPI events, they are often restricted to a given domain type. We describe DomPep, a method that can potentially be used to predict PPIs mediated by any modular domains. DomPep combines proteomic data with sequence information to achieve high accuracy and high coverage in PPI prediction. Proteomic binding data were employed to determine a simple yet novel parameter Ligand-Binding Similarity which, in turn, is used to calibrate Domain Sequence Identity and Position-Weighted-Matrix distance, two parameters that are used in constructing prediction models. Moreover, DomPep can be used to predict PPIs for both domains with experimental binding data and those without. Using the PDZ and SH2 domain families as test cases, we show that DomPep can predict PPIs with accuracies superior to existing methods. To evaluate DomPep as a discovery tool, we deployed DomPep to identify interactions mediated by three human PDZ domains. Subsequent in-solution binding assays validated the high accuracy of DomPep in predicting authentic PPIs at the proteome scale. Because DomPep makes use of only interaction data and the primary sequence of a domain, it can be readily expanded to include other types of modular domains.

The pepATTRACT web server for blind, large-scale peptide-protein docking.

Science.gov (United States)

de Vries, Sjoerd J; Rey, Julien; Schindler, Christina E M; Zacharias, Martin; Tuffery, Pierre

2017-07-03

Peptide-protein interactions are ubiquitous in the cell and form an important part of the interactome. Computational docking methods can complement experimental characterization of these complexes, but current protocols are not applicable on the proteome scale. pepATTRACT is a novel docking protocol that is fully blind, i.e. it does not require any information about the binding site. In various stages of its development, pepATTRACT has participated in CAPRI, making successful predictions for five out of seven protein-peptide targets. Its performance is similar or better than state-of-the-art local docking protocols that do require binding site information. Here we present a novel web server that carries out the rigid-body stage of pepATTRACT. On the peptiDB benchmark, the web server generates a correct model in the top 50 in 34% of the cases. Compared to the full pepATTRACT protocol, this leads to some loss of performance, but the computation time is reduced from ∼18 h to ∼10 min. Combined with the fact that it is fully blind, this makes the web server well-suited for large-scale in silico protein-peptide docking experiments. The rigid-body pepATTRACT server is freely available at http://bioserv.rpbs.univ-paris-diderot.fr/services/pepATTRACT. © The Author(s) 2017. Published by Oxford University Press on behalf of Nucleic Acids Research.

Elementary particles and high energy phenomena: Progress report

International Nuclear Information System (INIS)

Cumalat, J.P.

1988-01-01

This paper reviews the research being done at the University of Colorado in High Energy Physics. Topics discussed in this paper are: Charmed Photoproduction; Hadronic Production of Charm Particles; Photoproduction of States Containing Heavy Quarks; Electron-Positron Physics with the MAC Detector at PEP; Electron-Positron Physics with the Upgraded Mark II Detector at SLC; The SLD Detector at SLC; Nonperturbative Studies of QCD; Hadron Phenomenology - Application to Experiment; Perturbative QCD and Weak Matrix Elements; Quarkonium Physics; Supersymmetry, Supergravity, and Superstrings; and Experimental Gravity. 50 refs., 13 figs

Preliminary results on tests of a Cerenkov ring imaging device employing a photoionizing PWC

Energy Technology Data Exchange (ETDEWEB)

Durkin, S.; Honma, A.; Leith, D.W.G.S.

1978-08-01

A brief description of techniques and problems of ring imaging Cerenkov detectors employing photoionizing PWC's is discussed. Preliminary results on a one dimensional ring imaging device tested at SLAC in May and June of 1978 are then presented. These results include rough measurements of the Cerenkov ring in nitrogen, argon, neon, and helium produced by a collimated positron beam.

e+e- physics at PETRA - the first five years

International Nuclear Information System (INIS)

Sau Lan Wu

1984-03-01

PETRA (Positron-Electron Tandem Ring Accelerator) is located at DESY in Hamburg, Germany, and is the highest energy electron-positron storage ring in the world. This report gives a global review of the experimental investigations carried out at PETRA for the first five years of its operation beginning in 1978 by the five Collaborations CELLO, JADE, MARK J, PLUTO and TASSO. The physics objectives in the original proposals have largely been fullfilled. The emphasis of this review, based mainly on journal publications before July 15, 1983 (the fifth anniversary of the first successful storage on an electron beam at PETRA), is on the physics results, ranging over strong, electromagnetic and weak interactions. The topics covered include quark and gluon physics, inclusive particle production, electroweak interference, two-photon physics, and search for new particles. Although cited for comparison, no attempt has been made for any systematic coverage of the corresponding results from PEP of SLAC. (orig.)

Study of the machine background induced by the PEP-II collider with a mini-TPC. Study of the doubly-charmed decay of the B meson with the detector BaBar; Etude du bruit de fond engendre par la machine PEP-2 a l'aide d'une mini-TPC. Etude de la desintegration doublement charmee du meson B avec le detecteur BaBar

Energy Technology Data Exchange (ETDEWEB)

Trincaz-Duvoid, S

2001-01-01

The work presented in this thesis is divided into two parts. The first one deals with the machine background induced by the PEP-II collider. This study has been performed with a mini-TPC before the start of the BaBar experiment. The second part concerns the measurements of the branching ratio of the decay modes B{sup 0} {yields} D{sup *-}D(*){sup 0}K{sup +} and of the inclusive branching ratio Br(B{sup 0} {yields} K{sup {+-}}X). These measurements have been obtained with the first BaBar data. During the commissioning of the PEP-II collider, the charged tracks rate close to the interaction point has been measured with the mini-TPC. This study has pointed to the fact that the machine background was much higher than predicted by the simulation. These bad background conditions were due to the poor quality of the vacuum in the rings. This relatively high pressure in the rings produces electro-magnetic showers at the interaction point due to beam gas interactions. The potential risks for the BaBar detector due to the machine backgrounds have been clearly pointed out by the studies performed for this thesis. The addition of some collimators and a deep understanding of the machine have greatly reduced the background. Nevertheless, the radiation level in BaBar is continuously monitored in order to protect the detector. The study of the b {yields} cc-bar channel is an important point for the understanding of the overall picture of the B meson decay. With an integrated luminosity of 17.3 fb{sup -1} recorded by the BaBar detector the following branching ratio using exclusive reconstruction technique have been measured: Br(B{sup 0} {yields} D{sup *-}D{sup 0}K{sup +}) = (0.29 {+-} 0.06 (stat) {+-} (syst)) % Br(B{sup 0} {yields} D{sup *-}D{sup *0}K{sup +}) = (1.16 {+-} 0.15 (stat) {+-} 0.16 (syst)) % A partial reconstruction has also been developed. With an integrated luminosity of 8.9 fb{sup -1}, the branching ratio of B{sup 0} into D{sup *-}D{sup 0}K{sup +} has been measured

Influence of the metal ion on the enzyme activity and kinetics of PepA from Lactobacillus delbrueckii.

Science.gov (United States)

Ewert, Jacob; Glück, Claudia; Strasdeit, Henry; Fischer, Lutz; Stressler, Timo

2018-03-01

The aminopeptidase A (PepA; EC 3.4.11.7) belongs to the group of metallopeptidases with two bound metal ions per subunit (M1M2(PepA)) and is specific for the cleavage of N-terminal glutamic (Glu) and aspartic acid (Asp) and, in low amounts, serine (Ser) residues. Our group recently characterized the first PepA from a Lactobacillus strain. However, the characterization was performed using synthetic para-nitroaniline substrates and not original peptide substrates, as was done in the current study. Prior to the characterization using original peptide substrates, the PepA purified was converted to its inactive apo-form and eight different metal ions were tested to restore its activity. It was found that five of the metal ions were able to reactivate apo-PepA: Co 2+ , Cu 2+ , Mn 2+ , Ni 2+ and Zn 2+ . Interestingly, depending on the metal ion used for reactivation, the activity and the pH and temperature profile differed. Exemplarily, MnMn(PepA), NiNi(PepA) and ZnZn(PepA) had an activity optimum using MES buffer (50mM, pH 6.0) and 60°C, whereas the activity optimum changed to Na/K-phosphate-buffer (50mM, pH 7.0) and 55°C for CuCu(PepA). However, more important than the changes in optimum pH and temperature, the kinetic properties of PepA were affected by the metal ion used. While all PepA variants could release N-terminal Glu or Asp, only CoCo(PepA), NiNi(PepA) and CuCu(PepA) could release Ser from the particular peptide substrate. In addition, it was found that the enzyme efficiency (V max /K M ) and catalytic mechanism (positive cooperative binding (Hill coefficent; n), substrate inhibition (K IS )) were influenced by the metal ion. Exemplarily, a high cooperativity (n>2),K IS value >20mM and preference for N-terminal Glu were detected for CuCu(PepA). In summary, the results suggested that an exchange of the metal ion can be used for tailoring the properties of PepA for specific hydrolysis requirements. Copyright © 2017 Elsevier Inc. All rights reserved.

CESR Conversion Damping Ring Studies of Electron Cloud Instabilities (CESR-TA)

International Nuclear Information System (INIS)

Rubin, David L.; Palmer, Mark A.

2011-01-01

In the International Linear Collider, two linear accelerators will accelerate bunches of positrons and electrons to over a hundred billion electron volts and collide them in a central detector. In order to obtain useful collision rates, the bunches, each containing twenty billion particles, must be compressed to a cross section of a few nanometers by a few hundred nanometers. In order to prepare these ultra high density bunches, damping rings (DRs) are employed before the linear accelerators. The DRs take the high emittance bunches that are provided by the electron and positron sources and, through the process of radiation damping, squeeze them into ultra low emittance beams that are ready for the main linear accelerators. In the damping rings, a number of effects can prevent the successful preparation of the beams. In the electron ring, an effect known as the fast ion instability can lead to beam growth and, in the positron ring, the build-up of an electron cloud (EC), which interacts with the circulating bunches, can produce the same effect. EC build-up and the subsequent interaction of the cloud with the positron beam in the DR have been identified as major risks for the successful construction of a linear collider. The CESRTA research program at the Cornell Electron Storage Ring (CESR) was developed in order to study the build-up of the EC, the details of its impact on ultra low emittance beams, as well as methods to mitigate the impact of the cloud. In the DR, the EC forms when synchrotron photons radiated from the circulating beam strike the walls of the vacuum chamber, resulting in the emission of photoelectrons. These low energy electrons can be accelerated across the vacuum chamber by the electric field of the beam, and strike the walls, causing the emission of secondary electrons. The secondary electrons are subsequently accelerated into the walls yet again via the same mechanism. The result is that the EC can rapidly begin to fill the vacuum chamber. In

CESR Conversion Damping Ring Studies of Electron Cloud Instabilities (CESR-TA)

Energy Technology Data Exchange (ETDEWEB)

Rubin, David L.; Palmer, Mark A.

2011-08-02

In the International Linear Collider, two linear accelerators will accelerate bunches of positrons and electrons to over a hundred billion electron volts and collide them in a central detector. In order to obtain useful collision rates, the bunches, each containing twenty billion particles, must be compressed to a cross section of a few nanometers by a few hundred nanometers. In order to prepare these ultra high density bunches, damping rings (DRs) are employed before the linear accelerators. The DRs take the high emittance bunches that are provided by the electron and positron sources and, through the process of radiation damping, squeeze them into ultra low emittance beams that are ready for the main linear accelerators. In the damping rings, a number of effects can prevent the successful preparation of the beams. In the electron ring, an effect known as the fast ion instability can lead to beam growth and, in the positron ring, the build-up of an electron cloud (EC), which interacts with the circulating bunches, can produce the same effect. EC build-up and the subsequent interaction of the cloud with the positron beam in the DR have been identified as major risks for the successful construction of a linear collider. The CESRTA research program at the Cornell Electron Storage Ring (CESR) was developed in order to study the build-up of the EC, the details of its impact on ultra low emittance beams, as well as methods to mitigate the impact of the cloud. In the DR, the EC forms when synchrotron photons radiated from the circulating beam strike the walls of the vacuum chamber, resulting in the emission of photoelectrons. These low energy electrons can be accelerated across the vacuum chamber by the electric field of the beam, and strike the walls, causing the emission of secondary electrons. The secondary electrons are subsequently accelerated into the walls yet again via the same mechanism. The result is that the EC can rapidly begin to fill the vacuum chamber. In

A cryogenic current-measuring device with nano-ampere resolution at the storage ring TARN II

International Nuclear Information System (INIS)

Tanabe, T.; Chida, K.; Shinada, K.

1999-01-01

In cooler-ring experiments, an accurate and non-destructive current measurement is essential for determining the reaction cross sections. The lowest current which can be measured by the DC current transformer commonly used so far is some μA. In order to measure a low-beam current from nA to μA, we made a cryogenic current-measuring device using a superconducting quantum interference devices (SQUID), and measured the circulating ion current at the cooler ring TARN II. This paper gives the design and performance of the device

Glow discharge processing vs bakeout for aluminum storage ring vacuum chambers

International Nuclear Information System (INIS)

Dean, N.R.; Hoyt, E.W.; Palrang, M.T.; Walker, B.G.

1977-11-01

Experiments were carried out on laboratory and prototype scale systems in order to establish the feasibility of argon discharge processing the PEP storage ring aluminum vacuum chambers. Electron-induced desorption rates showed significant reductions following bakeout and/or argon glow discharge treatment (>10 19 ions cm -1 ). Data are presented and discussed in relation to advantages and problems associated with: water removal, argon trapping and subsequent release, electron energy dependence, discharge distribution, and surface plasma chemical effects

Pan European Phenological database (PEP725): a single point of access for European data

Science.gov (United States)

Templ, Barbara; Koch, Elisabeth; Bolmgren, Kjell; Ungersböck, Markus; Paul, Anita; Scheifinger, Helfried; Rutishauser, This; Busto, Montserrat; Chmielewski, Frank-M.; Hájková, Lenka; Hodzić, Sabina; Kaspar, Frank; Pietragalla, Barbara; Romero-Fresneda, Ramiro; Tolvanen, Anne; Vučetič, Višnja; Zimmermann, Kirsten; Zust, Ana

2018-02-01

The Pan European Phenology (PEP) project is a European infrastructure to promote and facilitate phenological research, education, and environmental monitoring. The main objective is to maintain and develop a Pan European Phenological database (PEP725) with an open, unrestricted data access for science and education. PEP725 is the successor of the database developed through the COST action 725 "Establishing a European phenological data platform for climatological applications" working as a single access point for European-wide plant phenological data. So far, 32 European meteorological services and project partners from across Europe have joined and supplied data collected by volunteers from 1868 to the present for the PEP725 database. Most of the partners actively provide data on a regular basis. The database presently holds almost 12 million records, about 46 growing stages and 265 plant species (including cultivars), and can be accessed via http://www.pep725.eu/. Users of the PEP725 database have studied a diversity of topics ranging from climate change impact, plant physiological question, phenological modeling, and remote sensing of vegetation to ecosystem productivity.

Pan European Phenological database (PEP725): a single point of access for European data

Science.gov (United States)

Templ, Barbara; Koch, Elisabeth; Bolmgren, Kjell; Ungersböck, Markus; Paul, Anita; Scheifinger, Helfried; Rutishauser, This; Busto, Montserrat; Chmielewski, Frank-M.; Hájková, Lenka; Hodzić, Sabina; Kaspar, Frank; Pietragalla, Barbara; Romero-Fresneda, Ramiro; Tolvanen, Anne; Vučetič, Višnja; Zimmermann, Kirsten; Zust, Ana

2018-06-01

The Pan European Phenology (PEP) project is a European infrastructure to promote and facilitate phenological research, education, and environmental monitoring. The main objective is to maintain and develop a Pan European Phenological database (PEP725) with an open, unrestricted data access for science and education. PEP725 is the successor of the database developed through the COST action 725 "Establishing a European phenological data platform for climatological applications" working as a single access point for European-wide plant phenological data. So far, 32 European meteorological services and project partners from across Europe have joined and supplied data collected by volunteers from 1868 to the present for the PEP725 database. Most of the partners actively provide data on a regular basis. The database presently holds almost 12 million records, about 46 growing stages and 265 plant species (including cultivars), and can be accessed via http://www.pep725.eu/ . Users of the PEP725 database have studied a diversity of topics ranging from climate change impact, plant physiological question, phenological modeling, and remote sensing of vegetation to ecosystem productivity.

Accelerator studies at cooler rings TARN and TARN II

International Nuclear Information System (INIS)

Katayama, Takeshi.

1992-07-01

Two ion cooler rings, TARN and TARN II were constructed and operated from 1975 to 1992 at the Institute for Nuclear Study, Univ. of Tokyo, for mainly accelerator studies concerning the beam accumulation, acceleration and cooling. The main subjects performed in these facilities were; 1) beam stacking in transverse and longitudinal phase spaces, 2) stochastic momentum cooling, 3) electron cooling, 4) synchrotron acceleration and 5) slow beam extraction. In the present paper, typical experimental results on these subjects, arc described as well as the basic physical idea underlying these experimental results. The technical details are out of scope of the present paper. They can be found in the other papers refered in the concerned section in the text. (author)

Exploratory studies, 1991

International Nuclear Information System (INIS)

1992-03-01

The Exploratory Studies Group is dedicated to advanced investigation of accelerators and radiation, primarily in the area of charged-particle beams and photon beams. Its primary mission is to explore the next steps in the development of particle accelerators and storage rings, which are important both for high-energy physics and for the wide range of disciplines now turning to synchrotron-radiation sources and free-electron lasers. Our research is therefore deeply committed to LBL's institutional goal of becoming a center for the generation and use of coherent and incoherent electromagnetic radiation of exceptional brightness, as well as for generic research on the future development of accelerators. A significant fraction of our effort is dedicated to general accelerator-physics research for facilities on the immediate horizon, but a vital part of our activities comprises research into exotic possibilities for charged-particle production, accumulation, acceleration, and storage. During this report period, we were proncipally involved in four general areas of study: Accelerator-physics research for the Advanced Light Source, the 1-2 GeV synchrotron radiation source now under construction at LBL. In collaboration with the Stanford Linear Accelerator Center, both the conceptual and the detailed design of PEP-II, an energy-asymmetric electron-positron collider, based on the PEP ring at SLAC and designed to serve as a B-meson factory. Studies of ultraviolet and infrared free-electron lasers based on linear accelerators and storage rings, in particular the conceptual design of an infrared free-electron laser for the proposed Chemical Dynamics Research Laboratory at LBL. Generic high-energy accelerator-physics and photon-beam research directed far into the future to envision facilities that would employ new techniques of particle-beam acceleration and storage and photon-beam generation

Calculation of the detection efficiency in liquid scintillators. II. Single positron emitters; Calculo de la eficiencia de deteccion en liquidos centelleadores. II Nucleidos que se desintegran por emision simple de positrones

Energy Technology Data Exchange (ETDEWEB)

Grau Malonda, A.; Garcia Torano, E.

1982-07-01

Counting efficiency as a function of the figure of merit for 30 positron emitters has been computed from the positron energy spectrum. Only the efficiency contribution of positrons has been taken into consideration. The contribution of the annihilation photons depending on the volume of the scintillator will be investigated in a near future. Efficiency vs figure of merit is plotted and tabulated. (Author) 19 refs.

Study on a high resolution positron emission tomography scanner for brain study

International Nuclear Information System (INIS)

Nohara, N.; Tomitani, T.; Yamamoto, M.; Murayama, H.; Tanaka, E.

1990-01-01

The spatial resolution of positron emission tomography (PET) scanners is usually limited by the finite size of crystals such as bismuth germanate (BGO). To attain high resolution as well as high sensitivity, it is essential to use a large number of small BGO crystals arranged in close-packing on circular rings. In developing high resolution PET scanners, however, there are two physical factors limiting the spatial resolution. One is the finite range of positrons before annihilation and the other the deviation from 180 degrees of annihilation photons. The effect of the factors on the spatial resolution has been evaluated for positron-emitting sources as a function of detector ring radius. A high resolution PET scanner has been developed for brain study, aiming to have spatial resolutions as high as less than 4-mm FWHM in tomographic plane and less than 6-mm FWHM in axial direction at the detector ring center. For the goal of the high resolutions a multi-segment type of photomultiplier tubes has been specially designed and developed, which allows one tube to be directly coupled by four BGO crystals. The scanner consists of five detector rings of 47-cm in diameter, using all 1200 BGO crystals each measuring 5 mm x 12 mm x 30 mm. The scanner provides simultaneous 9 images by combination of in-plane and cross-plane, offering a 24-cm dia. x7.4-cm field-of-view. Physical performance of the scanner was investigated. At the ring center, the spatial resolution in the tomographic plane was measured to be 3.5-mm FWHM. The axial resolution was measured to be 5.7-mm FWHM for in-plane and 5.3-mm FWHM for cross-plane. Sensitivity for a 20-cm dia. uniform source was measured to be 9.5 kcps/μCi/ml for in-plane and 15.3 kcps/μCi/ml for cross-plane. (J.P.N.)

Study of B⁰ → $\\bar{D}$^*0 Decay and Measurement of sin(2β)

Energy Technology Data Exchange (ETDEWEB)

Bomben, Marco [Univ. of Trieste (Italy)

2007-09-18

This thesis describes a measurement of a CP violating asymmetry in neutral B meson decays, ⁰ → $\\bar{D}$^*0, where D^*0 is a charmed meson and h⁰ is a light meson, performed on data collected by the BABAR experiment at the SLAC asymmetric-energy electron-positron collider PEP-II.

SuperB Progress Report for Accelerator

Energy Technology Data Exchange (ETDEWEB)

Biagini, M.E.; Boni, R.; Boscolo, M.; Buonomo, B.; Demma, T.; Drago, A.; Esposito, M.; Guiducci, S.; Mazzitelli, G.; Pellegrino, L.; Preger, M.A.; Raimondi, P.; Ricci, R.; Rotundo, U.; Sanelli, C.; Serio, M.; Stella, A.; Tomassini, S.; Zobov, M.; /Frascati; Bertsche, K.; Brachman, A.; /SLAC /Novosibirsk, IYF /INFN, Pisa /Pisa U. /Orsay, LAL /Annecy, LAPP /LPSC, Grenoble /IRFU, SPP, Saclay /DESY /Cockroft Inst. Accel. Sci. Tech. /U. Liverpool /CERN

2012-02-14

This report details the progress made in by the SuperB Project in the area of the Collider since the publication of the SuperB Conceptual Design Report in 2007 and the Proceedings of SuperB Workshop VI in Valencia in 2008. With this document we propose a new electron positron colliding beam accelerator to be built in Italy to study flavor physics in the B-meson system at an energy of 10 GeV in the center-of-mass. This facility is called a high luminosity B-factory with a project name 'SuperB'. This project builds on a long history of successful e+e- colliders built around the world, as illustrated in Figure 1.1. The key advances in the design of this accelerator come from recent successes at the DAFNE collider at INFN in Frascati, Italy, at PEP-II at SLAC in California, USA, and at KEKB at KEK in Tsukuba Japan, and from new concepts in beam manipulation at the interaction region (IP) called 'crab waist'. This new collider comprises of two colliding beam rings, one at 4.2 GeV and one at 6.7 GeV, a common interaction region, a new injection system at full beam energies, and one of the two beams longitudinally polarized at the IP. Most of the new accelerator techniques needed for this collider have been achieved at other recently completed accelerators including the new PETRA-3 light source at DESY in Hamburg (Germany) and the upgraded DAFNE collider at the INFN laboratory at Frascati (Italy), or during design studies of CLIC or the International Linear Collider (ILC). The project is to be designed and constructed by a worldwide collaboration of accelerator and engineering staff along with ties to industry. To save significant construction costs, many components from the PEP-II collider at SLAC will be recycled and used in this new accelerator. The interaction region will be designed in collaboration with the particle physics detector to guarantee successful mutual use. The accelerator collaboration will consist of several groups at present

Detectors, sampling, shielding, and electronics for positron emission tomography

International Nuclear Information System (INIS)

Derenzo, S.E.

1981-08-01

A brief discussion of the important design elements for positron emission tomographs is presented. The conclusions are that the instrumentation can be improved by the use of larger numbers of small, efficient detectors closely packed in many rings, the development of new detector materials, and novel electronic designs to reduce the deadtime and increase maximum event rates

PEP magnet power supply systems

International Nuclear Information System (INIS)

Jackson, L.T.

1977-01-01

The dc electrical requirements of the PEP magnets fall mainly into two categories: (1) high power and current of single polarity and (2) low-power bi-polar. The first category will be thyristor-chopper controlled off common 600 V dc busses. The second group will utilize continuously controlled push-pull transistor actuators

Experiences of HIV postexposure prophylaxis (PEP) among highly exposed men who have sex with men (MSM).

Science.gov (United States)

Palich, Romain; Martin-Blondel, Guillaume; Cuzin, Lise; Le Talec, Jean-Yves; Boyer, Pierre; Massip, Patrice; Delobel, Pierre

2017-11-01

HIV postexposure prophylaxis (PEP) is indicated after sexual exposure with high risk of transmission. Men who have sex with men (MSM) are the main target of PEP. The aim of our study was to investigate the experience and shortcomings of PEP among people with a high risk of HIV exposure. Subjects with ongoing follow-up for HIV infection and PEP history were selected for the qualitative study. Semistructured interviews were conducted at the patients' homes. They were audio-recorded, transcribed and deidentified before data analysis, double coding and thematic analysis with an inductive approach. Twenty-three patients were eligible for the qualitative study. Thirteen interviews were carried out. All patients were 20-60-year-old MSM. The median time between PEP and HIV diagnosis was 3.3 years (interquartile range (IQR) 25-75 =0.9-4.9). Many participants reported negative PEP experiences: awkward access to the PEP clinic, uneasiness and shame in the hospital setting, unpleasant interaction and moral disapprobation from the medical staff, treatment intolerance and prevention messages that were 'inconsistent with real life' CONCLUSION: Our data highlight PEP management failures among its target population that may have compromised any subsequent attempts to seek out PEP. Practitioners should be more aware of MSM sexual contexts and practices. PEP consultations should provide the opportunity to discuss prevention strategies with highly exposed HIV-negative subjects, which may include pre-exposure prophylaxis. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Linear theory of beam depolarization due to vertical betatron motion

International Nuclear Information System (INIS)

Chao, A.W.; Schwitters, R.F.

1976-06-01

It is well known that vertical betatron motion in the presence of quantum fluctuations leads to some degree of depolarization of a transversely polarized beam in electron-positron storage rings even for energies away from spin resonances. Analytic formulations of this problem, which require the use of simplifying assumptions, generally have shown that there exist operating energies where typical storage rings should exhibit significant beam polarization. Due to the importance of beam polarization in many experiments, we present here a complete calculation of the depolarization rate to lowest order in the perturbing fields, which are taken to be linear functions of the betatron motion about the equilibrium orbit. The results are applicable to most high energy storage rings. Explicit calculations are given for SPEAR and PEP. 7 refs., 8 figs

Recent improvements in luminosity at PEP

International Nuclear Information System (INIS)

Helm, R.; Allen, M.; Chao, A.

1983-03-01

We will describe improvements which have led to new records for peak and average luminosity at PEP. Comparison of recent results with several earlier lattice and optical modifications shows rather good correlation with the predictions of a beam-beam simulation program

Ca 2+ signaling by plant Arabidopsis thaliana Pep peptides depends on AtPepR1, a receptor with guanylyl cyclase activity, and cGMP-activated Ca 2+ channels

KAUST Repository

Qia, Zhi; Verma, Rajeev K.; Gehring, Christoph A; Yamaguchi, Yube; Zhao, Yichen; Ryan, Clarence A.; Berkowitz, Gerald A.

2010-01-01

receptor- like kinase receptor AtPepR1 has guanylyl cyclase activity, generating cGMP from GTP, and that cGMP can activate CNGC2- dependent cytosolic Ca 2+ elevation. AtPep-dependent expression of pathogen-defense genes (PDF1.2, MPK3, and WRKY33

A Monte-Carlo simulation of the equilibrium beam polarization in ultra-high energy electron (positron) storage rings

Energy Technology Data Exchange (ETDEWEB)

Duan, Zhe, E-mail: zhe.duan@ihep.ac.cn [Key Laboratory of Particle Acceleration Physics and Technology, Institute of High Energy Physics, Chinese Academy of Sciences, 100049 Beijing (China); University of Chinese Academy of Sciences, 100049 Beijing (China); Bai, Mei [Forschungszentrum Jülich GmbH, 52428 Jülich (Germany); Barber, Desmond P. [Deutsches Elektronen-Synchrotron, DESY, 22607 Hamburg (Germany); Qin, Qing [Key Laboratory of Particle Acceleration Physics and Technology, Institute of High Energy Physics, Chinese Academy of Sciences, 100049 Beijing (China)

2015-09-01

With the recently emerging global interest in building a next generation of circular electron–positron colliders to study the properties of the Higgs boson, and other important topics in particle physics at ultra-high beam energies, it is also important to pursue the possibility of implementing polarized beams at this energy scale. It is therefore necessary to set up simulation tools to evaluate the beam polarization at these ultra-high beam energies. In this paper, a Monte-Carlo simulation of the equilibrium beam polarization based on the Polymorphic Tracking Code (PTC) (Schmidt et al., 2002 [1]) is described. The simulations are for a model storage ring with parameters similar to those of proposed circular colliders in this energy range, and they are compared with the suggestion (Derbenev et al., 1979 [2]) that there are different regimes for the spin dynamics underlying the polarization of a beam in the presence of synchrotron radiation at ultra-high beam energies. In particular, it has been suggested that the so-called “correlated” crossing of spin resonances during synchrotron oscillations at current energies evolves into “uncorrelated” crossing of spin resonances at ultra-high energies.

A Monte-Carlo simulation of the equilibrium beam polarization in ultra-high energy electron (positron) storage rings

International Nuclear Information System (INIS)

Duan, Zhe; Bai, Mei; Barber, Desmond P.; Qin, Qing

2015-04-01

With the recently emerging global interest in building a next generation of circular electron-positron colliders to study the properties of the Higgs boson, and other important topics in particle physics at ultra-high beam energies, it is also important to pursue the possibility of implementing polarized beams at this energy scale. It is therefore necessary to set up simulation tools to evaluate the beam polarization at these ultra-high beam energies. In this paper, a Monte-Carlo simulation of the equilibrium beam polarization based on the Polymorphic Tracking Code(PTC) (Schmidt et al., 2002) is described. The simulations are for a model storage ring with parameters similar to those of proposed circular colliders in this energy range, and they are compared with the suggestion (Derbenev et al., 1978) that there are different regimes for the spin dynamics underlying the polarization of a beam in the presence of synchrotron radiation at ultra-high beam energies. In particular, it has been suggested that the so-called ''correlated'' crossing of spin resonances during synchrotron oscillations at current energies, evolves into ''uncorrelated'' crossing of spin resonances at ultra-high energies.

Optics Design and Performance of an Ultra-Low Emittance Damping Ring for the Compact Linear Collider

CERN Document Server

Korostelev, M S

2006-01-01

A high-energy (0.5-3.0 TeV centre of mass) electron-positron Compact Linear Collider (CLIC) is being studied at CERN as a new physics facility. The design study has been optimized for 3 TeV centre-of-mass energy. Intense bunches injected into the main linac must have unprecedentedly small emittances to achieve the design luminosity 1035cm-2s-1 required for the physics experiments. The positron and electron bunch trains will be provided by the CLIC injection complex. This thesis describes an optics design and performance of a positron damping ring developed for producing such ultra-low emittance beam. The linear optics of the CLIC damping ring is optimized by taking into account the combined action of radiation damping, quantum excitation and intrabeam scattering. The required beam emittance is obtained by using a TME (Theoretical Minimum Emittance) lattice with compact arcs and short period wiggler magnets located in dispersionfree regions. The damping ring beam energy is chosen as 2.42 GeV. The lattice featu...

Type II GaSb/GaAs quantum dot/ring stacks with extended photoresponse for efficient solar cells

Energy Technology Data Exchange (ETDEWEB)

Carrington, Peter James, E-mail: p.carrington@lancaster.ac.uk [Physics Department, Lancaster University, Lancaster LA1 4YB (United Kingdom); Mahajumi, Abu Syed [Physics Department, Lancaster University, Lancaster LA1 4YB (United Kingdom); Wagener, Magnus C.; Botha, Johannes Reinhardt [Department of Physics, Nelson Mandela Metropolitan University, Port Elizabeth (South Africa); Zhuang Qian; Krier, Anthony [Physics Department, Lancaster University, Lancaster LA1 4YB (United Kingdom)

2012-05-15

We report on the fabrication of GaAs based p-i-n solar cells containing 5 and 10 layers of type II GaSb quantum rings grown by molecular beam epitaxy. Solar cells containing quantum rings show improved efficiency at longer wavelengths into the near-IR extending up to 1500 nm and show enhanced short-circuit current under 1 sun illumination compared to a GaAs control cell. A reduction in the open-circuit voltage is observed due to the build-up of internal strain. The MBE growth, formation and photoluminescence of single and stacked layers of GaSb/GaAs quantum rings are also presented.

Type II GaSb/GaAs quantum dot/ring stacks with extended photoresponse for efficient solar cells

International Nuclear Information System (INIS)

Carrington, Peter James; Mahajumi, Abu Syed; Wagener, Magnus C.; Botha, Johannes Reinhardt; Zhuang Qian; Krier, Anthony

2012-01-01

We report on the fabrication of GaAs based p–i–n solar cells containing 5 and 10 layers of type II GaSb quantum rings grown by molecular beam epitaxy. Solar cells containing quantum rings show improved efficiency at longer wavelengths into the near-IR extending up to 1500 nm and show enhanced short-circuit current under 1 sun illumination compared to a GaAs control cell. A reduction in the open-circuit voltage is observed due to the build-up of internal strain. The MBE growth, formation and photoluminescence of single and stacked layers of GaSb/GaAs quantum rings are also presented.

Event rates to be expected at PEP

International Nuclear Information System (INIS)

Richter, B.

1988-01-01

As a guide for planning experiments at PEP, some estimates are given of average luminosity, charged and neutral particle yields vs. momentum, QED test capabilities, and weak interaction effects. 2 figs

The kicker magnet system for TRISTAN Accumulation Ring injection

International Nuclear Information System (INIS)

Sakamoto, Y.; Satoh, K.; Nakayama, H.

1994-12-01

The injection of electron beams to TRISTAN Accumulation Ring (AR) was started in November 1983 and the positron injection started in November 1985. For the injection of electron and positron beams to AR, the unique kicker system was developed. In the kicker power supply the charging to the main capacitor was done with the resonant charge system together with the auxiliary charging unit. The impedance matching circuit was added to the kicker magnet for getting the required current form with least reflecting oscillation. In this paper we report the performance of this kicker system. (author)

Recent results of BABAR

International Nuclear Information System (INIS)

Bernard, D.

2001-01-01

The BABAR detector at SLAC's PEP-II storage ring has collected data amounting to about 30.4 fb -1 until june 2001. Results on CP violation, and in particular search for direct CP violation, and measurement of rare B decays are presented

The beam energy measurement system for the Beijing electron-positron collider

International Nuclear Information System (INIS)

Zhang, J.Y.; Abakumova, E.V.; Achasov, M.N.; Blinov, V.E.; Cai, X.; Dong, H.Y.; Fu, C.D.; Harris, F.A.; Kaminsky, V.V.; Krasnov, A.A.; Liu, Q.; Mo, X.H.; Muchnoi, N.Yu.; Nikolaev, I.B.; Qin, Q.; Qu, H.M.; Olsen, S.L.; Pyata, E.E.; Shamov, A.G.; Shen, C.P.

2012-01-01

The beam energy measurement system (BEMS) for the upgraded Beijing electron-positron collider BEPC-II is described. The system is based on measuring the energies of Compton back-scattered photons. The relative systematic uncertainty of the electron and positron beam energy determination is estimated as 2⋅10 -5 .

Problems in obtaining polarized e+ and e- beams and perspectives for PEP

International Nuclear Information System (INIS)

Chao, A.W.

1980-09-01

A matrix formalism for polarization calculation, as well as its comparison with other methods, is briefly discussed. The prediction for SPEAR is compared with experimental measurements. An estimate is offered for the transverse polarization for PEP. Various schemes for obtaining the longitudinal polarization in PEP are studied

Pep-3D-Search: a method for B-cell epitope prediction based on mimotope analysis.

Science.gov (United States)

Huang, Yan Xin; Bao, Yong Li; Guo, Shu Yan; Wang, Yan; Zhou, Chun Guang; Li, Yu Xin

2008-12-16

The prediction of conformational B-cell epitopes is one of the most important goals in immunoinformatics. The solution to this problem, even if approximate, would help in designing experiments to precisely map the residues of interaction between an antigen and an antibody. Consequently, this area of research has received considerable attention from immunologists, structural biologists and computational biologists. Phage-displayed random peptide libraries are powerful tools used to obtain mimotopes that are selected by binding to a given monoclonal antibody (mAb) in a similar way to the native epitope. These mimotopes can be considered as functional epitope mimics. Mimotope analysis based methods can predict not only linear but also conformational epitopes and this has been the focus of much research in recent years. Though some algorithms based on mimotope analysis have been proposed, the precise localization of the interaction site mimicked by the mimotopes is still a challenging task. In this study, we propose a method for B-cell epitope prediction based on mimotope analysis called Pep-3D-Search. Given the 3D structure of an antigen and a set of mimotopes (or a motif sequence derived from the set of mimotopes), Pep-3D-Search can be used in two modes: mimotope or motif. To evaluate the performance of Pep-3D-Search to predict epitopes from a set of mimotopes, 10 epitopes defined by crystallography were compared with the predicted results from a Pep-3D-Search: the average Matthews correlation coefficient (MCC), sensitivity and precision were 0.1758, 0.3642 and 0.6948. Compared with other available prediction algorithms, Pep-3D-Search showed comparable MCC, specificity and precision, and could provide novel, rational results. To verify the capability of Pep-3D-Search to align a motif sequence to a 3D structure for predicting epitopes, 6 test cases were used. The predictive performance of Pep-3D-Search was demonstrated to be superior to that of other similar programs

The key determinants of perceived external prestige (PEP – Qualitative research approach

Directory of Open Access Journals (Sweden)

Tamara Sušanj Šulentić

2017-01-01

Full Text Available Perceived external prestige (PEP is a well-known concept oriented towards describing the way members of a certain organization interpret and assess their organisational reputation. Such perception can significantly affect employees’ identification and loyalty to the organisation as well as their job satisfaction and work performance. According to the social identification theory, people define themselves and others with respect to their belonging to a particular group or organization, and their basic motive is a personal need for self-respect and a sense of pride. Employees’ perception of being members of an important, reputable and significant organisation contributes to the feeling of self-respect, which increases their individual social value and status. According to literature, there are only few objections to the concept of PEP, mainly those related to the determination of its structure and, with it, to its management. Although there is a growing literature on PEP, it is still not clear whether PEP is a one-dimensional or a multidimensional construct. If PEP is a multidimensional concept, it is important to specify its key components, in order to enhance the management of favourable organizational prestige in a real work environment. The purpose of this paper was to determine the structure of PEP and important sources of information, based on which, employees value the prestige of their organisation. Qualitative research was conducted, comprising nine semi-structured interviews with communication experts working for a multinational organisation operating in several European countries. The results of this paper indicate that PEP is a multidimensional construct, with several components, important for its creation and management. Those components can be grouped into three main categories: track record of success and the position of the organisation on the market, social impact of the organisation on the immediate environment and the

Luminosity enhancements at SLAC

International Nuclear Information System (INIS)

Coward, D.H.

1984-04-01

Several ideas are discussed that have been proposed to improve the luminosity at the SPEAR and PEP electron-positron storage rings and to insure good luminosity at the SLAC Linear Collider. There have been two proposals studied recently for SPEAR: a Microbeta insertion using Samarium Cobalt permanent magnets, and a Minibeta insertion using conventional quadrupole magnets. The notations Microbeta and minibeta used here are somewhat arbitrary since the front faces of the first quadrupole magnets for both insertions are at nearly the same distance from the interaction point

EFRT M-12 Issue Resolution: Caustic-Leach Rate Constants from PEP and Laboratory-Scale Tests

Energy Technology Data Exchange (ETDEWEB)

Mahoney, Lenna A.; Rassat, Scot D.; Eslinger, Paul W.; Aaberg, Rosanne L.; Aker, Pamela M.; Golovich, Elizabeth C.; Hanson, Brady D.; Hausmann, Tom S.; Huckaby, James L.; Kurath, Dean E.; Minette, Michael J.; Sundaram, S. K.; Yokuda, Satoru T.

2010-01-01

Pacific Northwest National Laboratory (PNNL) has been tasked by Bechtel National Inc. (BNI) on the River Protection Project-Hanford Tank Waste Treatment and Immobilization Plant (RPP-WTP) project to perform research and development activities to resolve technical issues identified for the Pretreatment Facility (PTF). The Pretreatment Engineering Platform (PEP) was designed, constructed and operated as part of a plan to respond to issue M12, “Undemonstrated Leaching Processes” of the External Flowsheet Review Team (EFRT) issue response plan.( ) The PEP is a 1/4.5-scale test platform designed to simulate the WTP pretreatment caustic leaching, oxidative leaching, ultrafiltration solids concentration, and slurry washing processes. The PEP replicates the WTP leaching processes using prototypic equipment and control strategies. The PEP also includes non-prototypic ancillary equipment to support the core processing. The work described in this report addresses caustic leaching under WTP conditions, based on tests performed with a Hanford waste simulant. Because gibbsite leaching kinetics are rapid (gibbsite is expected to be dissolved by the time the final leach temperature is reached), boehmite leach kinetics are the main focus of the caustic-leach tests. The tests were completed at the laboratory-scale and in the PEP, which is a 1/4.5-scale mock-up of key PTF process equipment. Two laboratory-scale caustic-leach tests were performed for each of the PEP runs. For each PEP run, unleached slurry was taken from the PEP caustic-leach vessel for one batch and used as feed for both of the corresponding laboratory-scale tests.

Beam-beam interaction in e+-e- storage rings

International Nuclear Information System (INIS)

Le Duff, J.

1977-01-01

Colliding beams in electron-positron storage rings are discussed with particular reference to the space charge forces occuring during beam-beam interactions and their effect on beam current and consequently machine performance (maximum luminosity). The first section deals with linear beam-beam effects and discussses linear tune shift; the second section considers non-linear beam-beam effects and the creation on non-linear resonances. The last section poses questions of the possibility of extrapolating present results to future machines and discusses optimization of storage ring performance. (B.D.)

Evidence that the rabbit proton-peptide co-transporter PepT1 is a multimer when expressed in Xenopus laevis oocytes.

Science.gov (United States)

Panitsas, Konstantinos-E; Boyd, C A R; Meredith, David

2006-04-01

To test whether the rabbit proton-coupled peptide transporter PepT1 is a multimer, we have employed a combination of transport assays, luminometry and site-directed mutagenesis. A functional epitope-tagged PepT1 construct (PepT1-FLAG) was co-expressed in Xenopus laevis oocytes with a non-functional but normally trafficked mutant form of the same transporter (W294F-PepT1). The amount of PepT1-FLAG cRNA injected into the oocytes was kept constant, while the amount of W294F-PepT1 cRNA was increased over the mole fraction range of 0 to 1. The uptake of [(3)H]-D: -Phe-L: -Gln into the oocytes was measured at pH(out) 5.5, and the surface expression of PepT1-FLAG was quantified by luminometry. As the mole fraction of injected W294F-PepT1 increased, the uptake of D: -Phe-L: -Gln decreased. This occurred despite the surface expression of PepT1-FLAG remaining constant, and so we can conclude that PepT1 must be a multimer. Assuming that PepT1 acts as a homomultimer, the best fit for the modelling suggests that PepT1 could be a tetramer, with a minimum requirement of two functional subunits in each protein complex. Western blotting also showed the presence of higher-order complexes of PepT1-FLAG in oocyte membranes. It should be noted that we cannot formally exclude the possibility that PepT1 interacts with unidentified Xenopus protein(s). The finding that PepT1 is a multimer has important implications for the molecular modelling of this protein.

Electronic de-multipliers II (ring-shape systems)

International Nuclear Information System (INIS)

Raievski, V.

1948-09-01

This report describes a new type of ring-shape fast electronic counter (de-multiplier) with a resolution capacity equivalent to the one made by Regener (Rev. of Scientific Instruments USA 1946, 17, 180-89) but requiring two-times less electronic valves. This report follows the general description of electronic de-multipliers made by J. Ailloud (CEA--001). The ring comprises 5 flip-flop circuits with two valves each. The different elements of the ring are calculated with enough details to allow the transfer of this calculation to different valve types. (J.S.)

Fabrication of lithium ceramic pellets, rings and single crystals for irradiation in BEATRIX-II

International Nuclear Information System (INIS)

Slagle, O.D.; Noda, K.; Takahashi, T.

1989-04-01

BEATRIX-II is an IEA sponsored experiment of lithium ceramic solid breeder materials in the FFTF/MOTA. Li 2 O solid pellets and annular ring specimens were fabricated for in-situ tritium release tests. In addition, a series of single crystal and polycrystalline lithium ceramic samples were fabricated to determine the irradiation behavior and beryllium compatibility. 6 refs., 10 figs., 4 tabs

Terapêutica da sarcoidose: importância da avaliação da PEP

Directory of Open Access Journals (Sweden)

Ema Sacadura Leite

1998-01-01

sarcoidose pulmonar. ABSTRACT: SARCOIDOSIS THERAPY: IMPORTANCE OF PEP DETERMINATION: Clearance of 99mTc – DTPA may be a non invasive way to determinate Pulmonary Epithelial Permeability (PEP. The aim of our study was to assess PEP of patients with sarcoidosis and: 1 To correlate its value with the initial lung function tests values - VC, FEV1, St Cpt, DLCO, PaO2, TC, 67 Gallium pulmonary fixation and SACE determinations; 2 To evaluate if PEP can predict patients evolution after one year of follow up, being a valid indicator to decide about pulmonar sarcoidosis treatment.We studied 34 patients with biopsy proven sarcoidosis (mean age 43.3±10.9, 27/34 females, 20% stage 0, 23% stage 1, 26% stage II, 3 1% stage III, mean time of disease evolution 3. 7±5.4 years.Patients were divided in two groups a normal PEP – Group 0 (n=14 b increased PEP – Group 1 (n=20. Anova and Fisher testes were used to test 1 and study of change was made by Me Nemar test and analysis of covariance to test 2. We found a significant correlation of PEP values and VC (G0=102.6±18.3 vs G1=86.4±19.7, p=0.01, FEV, (G0=105.4±20.5 vs G1=85.8±21.5, p=0.019, DLCO (G0=100.4±19.4 vs G1=83.2±22.2, p=0.02 and lung 67 Gallium positivity (p=0.05. Regarding predictability of evolution there was a sugestion that initial PEP value would predict evolution of St Cpl (p=0.069.Our results suggest that PFP evaluation are probably useful in the decision of initiating (or reinstituting treatment in pulmonary sarcoidosis. Key Words: Sarcoidosis treatment, Pulmonary Epithelial Permeability, Palavras chave: Terapêutica na sarcoidose, Permeabilidade Epitelial Pulmonar

The Upgrade of the Neutron Induced Positron Source NEPOMUC

Science.gov (United States)

Hugenschmidt, C.; Ceeh, H.; Gigl, T.; Lippert, F.; Piochacz, C.; Pikart, P.; Reiner, M.; Weber, J.; Zimnik, S.

2013-06-01

In summer 2012, the new NEutron induced POsitron Source MUniCh (NEPOMUC) was installed and put into operation at the research reactor FRM II. At NEPOMUC upgrade 80% 113Cd enriched Cd is used as neutron-gamma converter in order to ensure an operation time of 25 years. A structure of Pt foils inside the beam tube generates positrons by pair production. Moderated positrons leaving the Pt front foil are electrically extracted and magnetically guided to the outside of the reactor pool. The whole design, including Pt-foils, the electric lenses and the magnetic fields, has been improved in order to enhance both the intensity and the brightness of the positron beam. After adjusting the potentials and the magnetic guide and compensation fields an intensity of about 3·109 moderated positrons per second is expected. During the first start-up, the measured temperatures of about 90°C ensure a reliable operation of the positron source. Within this contribution the features and the status of NEPOMUC upgrade are elucidated. In addition, an overview of recent positron beam experiments and current developments at the spectrometers is given.

Measurements of the electron cloud in the APS storage ring

International Nuclear Information System (INIS)

Harkey, K. C.

1999-01-01

Synchrotron radiation interacting with the vacuum chamber walls in a storage ring produce photoelectrons that can be accelerated by the beam, acquiring sufficient energy to produce secondary electrons in collisions with the walls. If the secondary-electron yield (SEY) coefficient of the wall material is greater than one, as is the case with the aluminum chambers in the Advanced Photon Source (APS) storage ring, a runaway condition can develop. As the electron cloud builds up along a train of stored positron or electron bunches, the possibility exists that a transverse perturbation of the head bunch will be communicated to trailing bunches due to interaction with the cloud. In order to characterize the electron cloud, a special vacuum chamber was built and inserted into the ring. The chamber contains 10 rudimentary electron-energy analyzers, as well as three targets coated with different materials. Measurements show that the intensity and electron energy distribution are highly dependent on the temporal spacing between adjacent bunches and the amount of current contained in each bunch. Furthermore, measurements using the different targets are consistent with what would be expected based on the SEY of the coatings. Data for both positron and electron beams are presented

Is there an optimal level of positive expiratory pressure (PEP) to improve walking tolerance in patients with severe COPD?

Science.gov (United States)

Russo, Davide; Simonelli, Carla; Paneroni, Mara; Saleri, Manuela; Piroddi, Ines Maria Grazia; Cardinale, Francesco; Vitacca, Michele; Nicolini, Antonello

2016-07-01

The application of positive expiratory pressure (PEP) devices during exercise had been proposed in order to counteract the pulmonary hyperinflation, reduce the dyspnea and thus increase the exercise tolerance in patients with severe chronic obstructive pulmonary disease (COPD). This randomized controlled crossover trial investigated the effect of two different levels of PEP (1 cmH2O and 10 cmH2O) on distance covered at 6minute walk test (6MWT) in patients with severe COPD. Secondary outcomes were the evaluation of PEP effects on physiological and pulmonary function variables. Seventy-two severe COPD patients, referred to our hospitals as in and out patients, were recruited. A basal 6MWT without devices was performed on the first day, and then repeated with PEP 1 cmH2O (PEP1) and 10 cmH2O (PEP10), with a randomized crossover design. Slow and forced spirometries, including the inspiratory capacity measure, were repeated before and after each 6MWT. 50 patients (average age 69,92 year, mean FEV1 41,42% of predicted) concluded the trial. The 6MWT improved significantly among both PEP levels and baseline (323,8 mt at baseline vs. 337,8 PEP1 and 341,8 PEP10; p<.002 and p<.018, respectively). The difference between PEP10 and PEP1 did not reach the significance. No improvements were found in pulmonary function, symptoms and physiological variables after the 6MWT. In patients with severe COPD, the application of 1 cmH2O of PEP seems to improve the exercise tolerance as 10 cmH2O, with similar dyspnea. Further studies should investigate the effects of low levels of PEP on aerobic training programs. Copyright © 2016 SEPAR. Published by Elsevier Espana. All rights reserved.

SLAC divertor channel entrance thermal stress analysis

International Nuclear Information System (INIS)

Johnson, G.L.; Stein, W.; Lu, S.C.; Riddle, R.A.

1985-01-01

X-ray beams emerging from the new SLAC electron-positron storage ring (PEP) impinge on the entrance to tangential divertor channels causing highly localized heating in the channel structure. Analyses were completed to determine the temperatures and thermally-induced stresses due to this heating. These parts are cooled with water flowing axially over them at 30 0 C. The current design and operating conditions should result in the entrance to the new divertor channel operating at a peak temperature of 123 0 C with a peak thermal stress at 91% of yield. Any micro-cracks that form due to thermally-induced stresses should not propagate to the coolant wall nor form a path for the coolant to leak into the storage ring vacuum. 34 figs., 4 tabs

EFRT M-12 Issue Resolution: Comparison of Filter Performance at PEP and CUF Scale

Energy Technology Data Exchange (ETDEWEB)

Daniel, Richard C.; Billing, Justin M.; Bontha, Jagannadha R.; Brown, Christopher F.; Eslinger, Paul W.; Hanson, Brady D.; Huckaby, James L.; Karri, Naveen K.; Kimura, Marcia L.; Kurath, Dean E.; Minette, Michael J.

2010-01-22

Pacific Northwest National Laboratory (PNNL) has been tasked by Bechtel National Inc. (BNI) on the River Protection Project-Hanford Tank Waste Treatment and Immobilization Plant (RPP-WTP) project to perform research and development activities to resolve technical issues identified for the Pretreatment Facility (PTF). The Pretreatment Engineering Platform (PEP) was designed, constructed, and operated as part of a plan to respond to issue M12, “Undemonstrated Leaching Processes” of the External Flowsheet Review Team (EFRT) issue response plan.(a) The PEP is a 1/4.5-scale test platform designed to simulate the WTP pretreatment caustic leaching, oxidative leaching, ultrafiltration solids concentration, and slurry washing processes. The PEP replicates the WTP leaching processes using prototypic equipment and control strategies. The PEP also includes non-prototypic ancillary equipment to support the core processing.

EFRT M-12 Issue Resolution: Comparison of PEP and Bench-Scale Oxidative Leaching Results

Energy Technology Data Exchange (ETDEWEB)

Rapko, Brian M.; Schonewill, Philip P.; Brown, Christopher F.; Eslinger, Paul W.; Fountain, Matthew S.; Hausmann, Tom S.; Huckaby, James L.; Hanson, Brady D.; Kurath, Dean E.; Minette, Michael J.

2010-01-01

Pacific Northwest National Laboratory (PNNL) has been tasked by Bechtel National Inc. (BNI) on the River Protection Project-Hanford Tank Waste Treatment and Immobilization Plant (RPP-WTP) project to perform research and development activities to resolve technical issues identified for the Pretreatment Facility (PTF). The Pretreatment Engineering Platform (PEP) was designed, constructed, and operated as part of a plan to respond to issue M12, “Undemonstrated Leaching Processes” of the External Flowsheet Review Team (EFRT) issue response plan.( ) The PEP is a 1/4.5-scale test platform designed to simulate the WTP pretreatment caustic leaching, oxidative leaching, ultrafiltration solids concentration, and slurry washing processes. The PEP replicates the WTP leaching processes using prototypic equipment and control strategies. The PEP also includes non-prototypic ancillary equipment to support the core processing.

EFRT M-12 Issue Resolution: Comparison of PEP and Bench-Scale Oxidative Leaching Results

International Nuclear Information System (INIS)

Rapko, Brian M.; Schonewill, Philip P.; Brown, Christopher F.; Eslinger, Paul W.; Fountain, Matthew S.; Hausmann, Tom S.; Huckaby, James L.; Hanson, Brady D.; Kurath, Dean E.; Minette, Michael J.

2010-01-01

Pacific Northwest National Laboratory (PNNL) has been tasked by Bechtel National Inc. (BNI) on the River Protection Project-Hanford Tank Waste Treatment and Immobilization Plant (RPP-WTP) project to perform research and development activities to resolve technical issues identified for the Pretreatment Facility (PTF). The Pretreatment Engineering Platform (PEP) was designed, constructed, and operated as part of a plan to respond to issue M12, 'Undemonstrated Leaching Processes' of the External Flowsheet Review Team (EFRT) issue response plan. The PEP is a 1/4.5-scale test platform designed to simulate the WTP pretreatment caustic leaching, oxidative leaching, ultrafiltration solids concentration, and slurry washing processes. The PEP replicates the WTP leaching processes using prototypic equipment and control strategies. The PEP also includes non-prototypic ancillary equipment to support the core processing.

EFRT M-12 Issue Resolution: Comparison of Filter Performance at PEP and CUF Scale

International Nuclear Information System (INIS)

Daniel, Richard C.; Billing, Justin M.; Bontha, Jagannadha R.; Brown, Christopher F.; Eslinger, Paul W.; Hanson, Brady D.; Huckaby, James L.; Karri, Naveen K.; Kimura, Marcia L.; Kurath, Dean E.; Minette, Michael J.

2010-01-01

Pacific Northwest National Laboratory (PNNL) has been tasked by Bechtel National Inc. (BNI) on the River Protection Project-Hanford Tank Waste Treatment and Immobilization Plant (RPP-WTP) project to perform research and development activities to resolve technical issues identified for the Pretreatment Facility (PTF). The Pretreatment Engineering Platform (PEP) was designed, constructed, and operated as part of a plan to respond to issue M12, 'Undemonstrated Leaching Processes' of the External Flowsheet Review Team (EFRT) issue response plan.(a) The PEP is a 1/4.5-scale test platform designed to simulate the WTP pretreatment caustic leaching, oxidative leaching, ultrafiltration solids concentration, and slurry washing processes. The PEP replicates the WTP leaching processes using prototypic equipment and control strategies. The PEP also includes non-prototypic ancillary equipment to support the core processing.

Evolutionary divergence of the plant elicitor peptides (Peps) and their receptors: interfamily incompatibility of perception but compatibility of downstream signalling

KAUST Repository

Lori, M.

2015-05-22

Plant elicitor peptides (Peps) are potent inducers of pattern-triggered immunity and amplify the immune response against diverse pathogens. Peps have been discovered and studied extensively in Arabidopsis and only recently orthologs in maize were also identified and characterized in more detail. Here, the presence of PROPEPs, the Pep precursors, and PEPRs, the Pep receptors, was investigated within the plant kingdom. PROPEPs and PEPRs were identified in most sequenced species of the angiosperms. The conservation and compatibility of the Pep-PEPR-system was analysed by using plants of two distantly related dicot families, Brassicaceae and Solanaceae, and a representative family of monocot plants, the Poaceae. All three plant families contain important crop plants, including maize, rice, tomato, potato, and canola. Peps were not recognized by species outside of their plant family of origin, apparently because of a divergence of the Pep sequences. Three family-specific Pep motifs were defined and the integration of such a motif into the Pep sequence of an unrelated Pep enabled its perception. Transient transformation of Nicotiana benthamiana with the coding sequences of the AtPEPR1 and ZmPEPR1a led to the recognition of Pep peptides of Brassicaceae or Poaceae origin, respectively, and to the proper activation of downstream signalling. It was concluded that signalling machinery downstream of the PEPRs is highly conserved whereas the leucine-rich repeat domains of the PEPRs co-evolved with the Peps, leading to distinct motifs and, with it, interfamily incompatibility.

Al18F-Labeling Of Heat-Sensitive Biomolecules for Positron Emission Tomography Imaging

Science.gov (United States)

Cleeren, Frederik; Lecina, Joan; Ahamed, Muneer; Raes, Geert; Devoogdt, Nick; Caveliers, Vicky; McQuade, Paul; Rubins, Daniel J; Li, Wenping; Verbruggen, Alfons; Xavier, Catarina; Bormans, Guy

2017-01-01

Positron emission tomography (PET) using radiolabeled biomolecules is a translational molecular imaging technology that is increasingly used in support of drug development. Current methods for radiolabeling biomolecules with fluorine-18 are laborious and require multistep procedures with moderate labeling yields. The Al18F-labeling strategy involves chelation in aqueous medium of aluminum mono[18F]fluoride ({Al18F}2+) by a suitable chelator conjugated to a biomolecule. However, the need for elevated temperatures (100-120 °C) required for the chelation reaction limits its widespread use. Therefore, we designed a new restrained complexing agent (RESCA) for application of the AlF strategy at room temperature. Methods. The new chelator RESCA was conjugated to three relevant biologicals and the constructs were labeled with {Al18F}2+ to evaluate the generic applicability of the one-step Al18F-RESCA-method. Results. We successfully labeled human serum albumin with excellent radiochemical yields in less than 30 minutes and confirmed in vivo stability of the Al18F-labeled protein in rats. In addition, we efficiently labeled nanobodies targeting the Kupffer cell marker CRIg, and performed µPET studies in healthy and CRIg deficient mice to demonstrate that the proposed radiolabeling method does not affect the functional integrity of the protein. Finally, an affibody targeting HER2 (PEP04314) was labeled site-specifically, and the distribution profile of (±)-[18F]AlF(RESCA)-PEP04314 in a rhesus monkey was compared with that of [18F]AlF(NOTA)-PEP04314 using whole-body PET/CT. Conclusion. This generic radiolabeling method has the potential to be a kit-based fluorine-18 labeling strategy, and could have a large impact on PET radiochemical space, potentially enabling the development of many new fluorine-18 labeled protein-based radiotracers. PMID:28824726

Al18F-Labeling Of Heat-Sensitive Biomolecules for Positron Emission Tomography Imaging.

Science.gov (United States)

Cleeren, Frederik; Lecina, Joan; Ahamed, Muneer; Raes, Geert; Devoogdt, Nick; Caveliers, Vicky; McQuade, Paul; Rubins, Daniel J; Li, Wenping; Verbruggen, Alfons; Xavier, Catarina; Bormans, Guy

2017-01-01

Positron emission tomography (PET) using radiolabeled biomolecules is a translational molecular imaging technology that is increasingly used in support of drug development. Current methods for radiolabeling biomolecules with fluorine-18 are laborious and require multistep procedures with moderate labeling yields. The Al 18 F-labeling strategy involves chelation in aqueous medium of aluminum mono[ 18 F]fluoride ({Al 18 F} 2+ ) by a suitable chelator conjugated to a biomolecule. However, the need for elevated temperatures (100-120 °C) required for the chelation reaction limits its widespread use. Therefore, we designed a new restrained complexing agent (RESCA) for application of the AlF strategy at room temperature. Methods. The new chelator RESCA was conjugated to three relevant biologicals and the constructs were labeled with {Al 18 F} 2+ to evaluate the generic applicability of the one-step Al 18 F-RESCA-method. Results. We successfully labeled human serum albumin with excellent radiochemical yields in less than 30 minutes and confirmed in vivo stability of the Al 18 F-labeled protein in rats. In addition, we efficiently labeled nanobodies targeting the Kupffer cell marker CRIg, and performed µPET studies in healthy and CRIg deficient mice to demonstrate that the proposed radiolabeling method does not affect the functional integrity of the protein. Finally, an affibody targeting HER2 (PEP04314) was labeled site-specifically, and the distribution profile of (±)-[ 18 F]AlF(RESCA)-PEP04314 in a rhesus monkey was compared with that of [ 18 F]AlF(NOTA)-PEP04314 using whole-body PET/CT. Conclusion. This generic radiolabeling method has the potential to be a kit-based fluorine-18 labeling strategy, and could have a large impact on PET radiochemical space, potentially enabling the development of many new fluorine-18 labeled protein-based radiotracers.

Positron emission tomography with Positome, 2

International Nuclear Information System (INIS)

Nukui, Hideaki; Yamamoto, Y.L.; Thompson, C.J.; Feindel, W.

1979-01-01

Positron emission tomography with Positome II using 68 Ga-EDTA was performed in cases with brain tumor and cerebral arteriovenous malformation. A significant focal uptake in static study and hemodynamic changes in dynamic study were noted in all cases except one case with intracranial lipoma. Comparing this method with sup(99m) Tc-pertechnetate cerebral image study and computerized axial tomography, the diagnostic rate for detecting brain tumor was almost equal in all of these three methods. However, detecting and localizing was easier and clearer in static positron emission tomography with 68 Ga-EDTA than in sup(99m) Tc-pertechnetate cerebral image and computerized axial tomography without infusion of contrast medium. Furthermore, static positron emission tomography with 68 Ga-EDTA was superior to computerized axial tomography without infusion of contrast medium for detecting cerebral arteriovenous malformation. Concerning dynamic positron emission tomography with 68 Ga-EDTA, semiquantitative values obtained by this method correlated well with findings of computerized axial tomography and was thought to be more precise and in detail than the findings of sup(99m) Tc-pertechnetate cerebral image study. Summation of the previous studies about dynamic positron emission tomography with 77 Kr in occlusive cerebrovascular disease is also reported. In conclusion, static positron emission tomography with 68 Ga-EDTA is a very useful diagnostic method for detecting and localizing brain tumor and cerebral arteriovenous malformation without any attendant complications. Furthermore, a good combination of static and dynamic positron emission tomography and computerized axial tomography appear to be outstandingly effective for not only detecting the lesion but also understanding the pathophysiological aspect in cases with various intracranial lesions. (author)

The FERRUM project: an extremely long radiative lifetime in Ti II measured in an ion storage ring

International Nuclear Information System (INIS)

Hartman, H; Rostohar, D; Derkatch, A; Lundin, P; Schef, P; Johansson, S; Lundberg, H; Mannervik, S; Norlin, L-O; Royen, P

2003-01-01

We have extended the laser probing technique at the CRYRING storage ring to measurement of the extremely long lifetime (28 s) of the metastable 3d 2 ( 3 P)4s b 4 P 5/2 level in Ti II. The result obtained demonstrates the power of this method for investigation of such long-lived levels. This is the first experimental lifetime investigation of metastable states in Ti II. (letter to the editor)

Conceptual design of a slow positron source based on a magnetic trap

CERN Document Server

Volosov, V I; Mezentsev, N A

2001-01-01

A unique 10.3 T superconducting wiggler was designed and manufactured at BINP SB RAS. The installation of this wiggler in the SPring-8 storage ring provides a possibility to generate a high-intensity beam of photons (SR) with energy above 1 MeV (Ando et al., J. Synchrotron Radiat. 5 (1998) 360). Conversion of photons to positrons on high-Z material (tungsten) targets creates an integrated positron flux more than 10 sup 1 sup 3 particles per second. The energy spectrum of the positrons has a maximum at 0.5 MeV and the half-width about 1 MeV (Plokhoi et al., Jpn. J. Appl. Phys. 38 (1999) 604). The traditional methods of positron moderation have the efficiency epsilon=N sub s /N sub f of 10 sup - sup 4 (metallic moderators) to 10 sup - sup 2 (solid rare gas moderators) (Mills and Gullikson, Appl. Phys. Lett. 49 (1986) 1121). The high flux of primary positrons restricts the choice to a tungsten moderator that has epsilon approx 10 sup - sup 4 only (Schultz, Nuc. Instr. and Meth. B 30 (1988) 94). The aim of our pr...

Overview of collective effects in the NLC main damping rings

International Nuclear Information System (INIS)

Wolski, A.; Santis, S. de

2002-01-01

The present design for the NLC Main Damping Rings (MDRs) meets the specifications for acceptance and extracted emittance, in the limit of zero current. However, the relatively large bunch charge and moderate energy mean that a variety of collective effects can impact the beam dynamics, leading to loss of stability or increase of equilibrium emittance. These effects include intrabeam scattering, impedance from numerous sources, fast ion instability, and (in the positron ring) electron cloud. In this note, we survey the expected impact on damping ring performance from each of a number of collective effects, and discuss the priorities for future studies in this area

Hazard Analysis for the Pretreatment Engineering Platform (PEP)

Energy Technology Data Exchange (ETDEWEB)

Sullivan, Robin S.; Geeting, John GH; Lawrence, Wesley E.; Young, Jonathan

2008-07-10

The Pretreatment Engineering Platform (PEP) is designed to perform a demonstration on an engineering scale to confirm the Hanford Waste Treatment Plant Pretreatment Facility (PTF) leaching and filtration process equipment design and sludge treatment process. The system will use scaled prototypic equipment to demonstrate sludge water wash, caustic leaching, oxidative leaching, and filtration. Unit operations to be tested include pumping, solids washing, chemical reagent addition and blending, heating, cooling, leaching, filtration, and filter cleaning. In addition, the PEP will evaluate potential design changes to the ultrafiltration process system equipment to potentially enhance leaching and filtration performance as well as overall pretreatment throughput. The skid-mounted system will be installed and operated in the Processing Development Laboratory-West at Pacific Northwest National Laboratory (PNNL) in Richland, Washington.

Positron annihilation in low-temperature rare gases. II. Argon and neon

International Nuclear Information System (INIS)

Canter, K.F.; Roellig, L.O.

1975-01-01

Lifetime measurements of slow-positron and ortho-positronium (o-Ps) annihilation were made in argon and neon gases at room temperature and below. The argon experiments cover the temperature range 115 to 300 0 K and the density range 0.0356 to 0.0726 g/cm 3 (approximately equal to 20 to 40 amagat). The slow-positron spectra in argon exhibit a departure from free-positron annihilation below 200 0 K. The departure becomes more marked as the temperature is lowered. No deviation from free o-Ps pickoff annihilation is observed in argon at low temperatures. The neon measurements cover the temperature range 30 to 300 0 K and the density range 0.032 to 0.89 g/cm 3 (approximately equal to 35 to 980 amagat). No effect of temperature on the slow-positron spectra throughout the temperature and density ranges investigated in neon is observed. The spectra are very exponential with a corresponding decay rate which is temperature as well as time independent and is directly proportional to density over the ranges investigated. The o-Ps data are more eventful in that the o-Ps lifetime at near-liquid densities is approximately 20 nsec, a factor of nearly 4 greater than the value obtained using the pickoff-annihilation coefficient obtained at lower densities. This is evidence for positronium-induced cavities in low-temperature neon. A brief discussion of the argon and neon results is given in the context of the explanations offered for the low-temperature effects observed in helium gas

Perception of Arabidopsis AtPep peptides, but not bacterial elicitors, accelerates starvation-induced senescence

Directory of Open Access Journals (Sweden)

Kay eGully

2015-01-01

Full Text Available Members of the AtPep group of Arabidopsis endogenous peptides have frequently been reported to induce pattern-triggered immunity and to increase resistance to diverse pathogens by amplifying the innate immune response. Here, we made the surprising observation that dark-induced leaf senescence was accelerated by the presence of Peps. Adult leaves as well as leaf discs of Col-0 wild type plants showed a Pep-triggered early onset of chlorophyll breakdown and leaf yellowing whereas pepr1 pepr2 double mutant plants were insensitive. In addition, this response was dependent on ethylene signaling and inhibited by the addition of cytokinins. Notably, addition of the bacterial elicitors flg22 or elf18, both potent inducers of pattern-triggered immunity, did not provoke an early onset of leaf senescence.Continuous darkness leads to energy deprivation and starvation and therewith promotes leaf senescence. We found that continuous darkness also strongly induced PROPEP3 transcription. Moreover, Pep-perception led to a rapid induction of PAO, APG7 and APG8a, genes indispensable for chlorophyll degradation as well as autophagy, respectively, and all three hallmarks of starvation and senescence. Notably, addition of sucrose as a source of energy inhibited the Pep-triggered early onset of senescence. In conclusion, we report that Pep-perception accelerates dark/starvation-induced senescence via an early induction of chlorophyll degradation and autophagy. This represents a novel and unique characteristic of PEPR signaling, unrelated to pattern-triggered immunity.

Electron Cloud Build Up and Instability in the CLIC Damping Rings

CERN Document Server

Rumolo, G; Papaphilippou, Y

2008-01-01

Electron cloud can be formed in the CLIC positron damping ring and cause intolerable tune shift and beam instability. Build up simulations with the Faktor2 code, developed at CERN, have been done to predict the cloud formation in the arcs and wigglers of the damping rings. HEADTAIL simulations have been used to study the effect of this electron cloud on the beam and assess the thresholds above which the electron cloud instability would set in.

Polarized positrons in Jefferson lab electron ion collider (JLEIC)

Science.gov (United States)

Lin, Fanglei; Grames, Joe; Guo, Jiquan; Morozov, Vasiliy; Zhang, Yuhong

2018-05-01

The Jefferson Lab Electron Ion Collider (JLEIC) is designed to provide collisions of electron and ion beams with high luminosity and high polarization to reach new frontier in exploration of nuclear structure. The luminosity, exceeding 1033 cm-2s-1 in a broad range of the center-of-mass (CM) energy and maximum luminosity above 1034 cm-2s-1, is achieved by high-rate collisions of short small-emittance low-charge bunches with proper cooling of the ion beam and synchrotron radiation damping of the electron beam. The polarization of light ion species (p, d, 3He) and electron can be easily preserved, manipulated and maintained by taking advantage of the unique figure-8 shape rings. With a growing physics interest, polarized positron-ion collisions are considered to be carried out in the JLEIC to offer an additional probe to study the substructure of nucleons and nuclei. However, the creation of polarized positrons with sufficient intensity is particularly challenging. We propose a dedicated scheme to generate polarized positrons. Rather than trying to accumulate "hot" positrons after conversion, we will accumulate "cold" electrons before conversion. Charge accumulation additionally provides a novel means to convert high repetition rate (>100 MHz) electron beam from the gun to a low repetition rate (<100 MHz) positron beam for broad applications. In this paper, we will address the scheme, provide preliminary estimated parameters and explain the key areas to reach the desired goal.

Five-year cost-effectiveness of the Patient Empowerment Programme (PEP) for type 2 diabetes mellitus in primary care.

Science.gov (United States)

Lian, Jinxiao; McGhee, Sarah M; So, Ching; Chau, June; Wong, Carlos K H; Wong, William C W; Lam, Cindy L K

2017-09-01

This study evaluated the short-term cost-effectiveness of the Patient Empowerment Programme (PEP) for diabetes mellitus (DM) in Hong Kong. Propensity score matching was used to select a matched group of PEP and non-PEP subjects. A societal perspective was adopted to estimate the cost of PEP. Outcome measures were the cumulative incidence of all-cause mortality and diabetic complication over a 5-year follow-up period and the number needed to treat (NNT) to avoid 1 event. The incremental cost-effectiveness ratio (ICER) of cost per event avoided was calculated using the PEP cost per subject multiplied by the NNT. The PEP cost per subject from the societal perspective was US$247. There was a significantly lower cumulative incidence of all-cause mortality (2.9% vs 4.6%, P US$14 465, US$19 617 and US$30 796, respectively. The extra amount allocated to managing PEP was small and it appears cost-effective in the short-term as an addition to RAMP. © 2017 John Wiley & Sons Ltd.

A new lattice for PEP

International Nuclear Information System (INIS)

Rees, J.; Wiedemann, H.

1976-01-01

A new low-beta configuration has been proposed for PEP which has a reduced β/sub y/* and is capable of delivering design luminosity with lower circulating beam currents that those required in the standard configuration described in the Conceptual Design Report of February, 1976. A feasibility study has been carried out and it is reported in PTM-65, September 8, 1976, by Lee, Morton and Wiedemann. The beam-stay-clear region is specified in PTM-66, September 3, 1976 by H. Wiedemann. The principal advantages of the new lattice are that the lower beam currents lead to lower higher-order-mode power and permit reduction of the total rf power required which in turn reduces both capital cost and operating cost. Its disadvantages stem primarily from the relatively high maximum beta values which occur in the interaction-region quadrupoles. These produce high chromaticities which require a generally stronger sextupole system for their compensation. The advantages outweigh the disadvantages and the new 11-cm-beta configuration has been adopted as the design configuration for energies of 15-GeV and lower. In the remainder of this report we shall discuss the implications of this new configuration for the various systems of PEP. 1 fig., 3 tabs

Positron-molecule interactions and corresponding positron attachment to molecules. As a basis for positron emission tomography (PET)

International Nuclear Information System (INIS)

Tachikawa, Masanori; Kimura, Mineo; Pichl, Lukas

2007-01-01

Through positron and electron interactions, they annihilate emitting primarily two gamma rays with 180-degree opposite directions. Positron spectroscopy using the characteristics of these gamma rays has been employed for analyzing various properties of material as well as for positron emission tomography (PET). However, its fundamental physics of positron-electron interactions and resulting features of emitting gamma rays are not well understood. By obtaining better understanding of positron interactions, it should become possible to provide the firm bases for positron spectroscopy in finer accuracy and quality. Here, we propose a significant mechanism for positron annihilation through positron attachment process, which may help increase the quality of positron spectroscopy. (author)

Using Ring Strain to Control 4π-Electrocyclization Reactions: Torquoselectivity in Ring Closing of Medium-Ring Dienes and Ring Opening of Bicyclic Cyclobutenes.

Science.gov (United States)

Boon, Byron A; Green, Aaron G; Liu, Peng; Houk, K N; Merlic, Craig A

2017-05-05

Syntheses of strained cyclic dienes were accomplished via palladium(II)-catalyzed oxidative cyclizations of terminal bis(vinylboronate esters). The reactions generate strained (E,E)-1,3-dienes that undergo spontaneous 4π-electrocyclizations to form bicyclic cyclobutenes. Formation of the cyclobutenes is driven by the strain in the medium-ring (E,E)-1,3-diene intermediate. Thermal ring openings of the cyclobutenes give (Z,Z)-1,3-diene products, again for thermodynamic reasons. DFT calculations verified the thermodynamic versus kinetic control of the reactions, and kinetic studies are in excellent agreement with the calculated energy changes. An extension of the tandem coupling/4π-electrocyclization pathway was demonstrated by a palladium(II)-catalyzed oxidative homocoupling/8π-electrocyclization cascade.

Transduction of PEP-1-heme oxygenase-1 into insulin-producing INS-1 cells protects them against cytokine-induced cell death

Energy Technology Data Exchange (ETDEWEB)

Lee, Su Jin; Kang, Hyung Kyung [Department of Physiology, College of Medicine, Hallym University, Chunchon 200-702 (Korea, Republic of); Song, Dong Keun [Department of Pharmacology, College of Medicine, Hallym University, Chunchon 200-702 (Korea, Republic of); Eum, Won Sik; Park, Jinseu [Department of Biomedical Science and Research Institute of Bioscience and Biotechnology, Hallym University, Chunchon 200-702 (Korea, Republic of); Choi, Soo Young, E-mail: sychoi@hallym.ac.kr [Department of Biomedical Science and Research Institute of Bioscience and Biotechnology, Hallym University, Chunchon 200-702 (Korea, Republic of); Kwon, Hyeok Yil, E-mail: hykwon@hallym.ac.kr [Department of Physiology, College of Medicine, Hallym University, Chunchon 200-702 (Korea, Republic of)

2015-06-05

Pro-inflammatory cytokines play a crucial role in the destruction of pancreatic β-cells, thereby triggering the development of autoimmune diabetes mellitus. We recently developed a cell-permeable fusion protein, PEP-1-heme oxygenase-1 (PEP-1-HO-1) and investigated the anti-inflammatory effects in macrophage cells. In this study, we transduced PEP-1-HO-1 into INS-1 insulinoma cells and examined its protective effect against cytokine-induced cell death. PEP-1-HO-1 was successfully delivered into INS-1 cells in time- and dose-dependent manner and was maintained within the cells for at least 48 h. Pre-treatment with PEP-1-HO-1 increased the survival of INS-1 cells exposed to cytokine mixture (IL-1β, IFN-γ, and TNF-α) in a dose-dependent manner. PEP-1-HO-1 markedly decreased cytokine-induced production of reactive oxygen species (ROS), nitric oxide (NO), and malondialdehyde (MDA). These protective effects of PEP-1-HO-1 against cytokines were correlated with the changes in the levels of signaling mediators of inflammation (iNOS and COX-2) and cell apoptosis/survival (Bcl-2, Bax, caspase-3, PARP, JNK, and Akt). These results showed that the transduced PEP-1-HO-1 efficiently prevented cytokine-induced cell death of INS-1 cells by alleviating oxidative/nitrosative stresses and inflammation. Further, these results suggested that PEP-1-mediated HO-1 transduction may be a potential therapeutic strategy to prevent β-cell destruction in patients with autoimmune diabetes mellitus. - Highlights: • We showed that PEP-1-HO-1 was efficiently delivered into INS-1 cells. • Transduced PEP-1-HO-1 exerted a protective effect against cytokine-induced cell death. • Transduced PEP-1-HO-1 inhibited cytokine-induced ROS and NO accumulation. • PEP-1-HO-1 suppressed cytokine-induced expression of iNOS, COX-2, and Bax. • PEP-1-HO-1 transduction may be an efficient tool to prevent β-cell destruction.

Transduction of PEP-1-heme oxygenase-1 into insulin-producing INS-1 cells protects them against cytokine-induced cell death

International Nuclear Information System (INIS)

Lee, Su Jin; Kang, Hyung Kyung; Song, Dong Keun; Eum, Won Sik; Park, Jinseu; Choi, Soo Young; Kwon, Hyeok Yil

2015-01-01

Pro-inflammatory cytokines play a crucial role in the destruction of pancreatic β-cells, thereby triggering the development of autoimmune diabetes mellitus. We recently developed a cell-permeable fusion protein, PEP-1-heme oxygenase-1 (PEP-1-HO-1) and investigated the anti-inflammatory effects in macrophage cells. In this study, we transduced PEP-1-HO-1 into INS-1 insulinoma cells and examined its protective effect against cytokine-induced cell death. PEP-1-HO-1 was successfully delivered into INS-1 cells in time- and dose-dependent manner and was maintained within the cells for at least 48 h. Pre-treatment with PEP-1-HO-1 increased the survival of INS-1 cells exposed to cytokine mixture (IL-1β, IFN-γ, and TNF-α) in a dose-dependent manner. PEP-1-HO-1 markedly decreased cytokine-induced production of reactive oxygen species (ROS), nitric oxide (NO), and malondialdehyde (MDA). These protective effects of PEP-1-HO-1 against cytokines were correlated with the changes in the levels of signaling mediators of inflammation (iNOS and COX-2) and cell apoptosis/survival (Bcl-2, Bax, caspase-3, PARP, JNK, and Akt). These results showed that the transduced PEP-1-HO-1 efficiently prevented cytokine-induced cell death of INS-1 cells by alleviating oxidative/nitrosative stresses and inflammation. Further, these results suggested that PEP-1-mediated HO-1 transduction may be a potential therapeutic strategy to prevent β-cell destruction in patients with autoimmune diabetes mellitus. - Highlights: • We showed that PEP-1-HO-1 was efficiently delivered into INS-1 cells. • Transduced PEP-1-HO-1 exerted a protective effect against cytokine-induced cell death. • Transduced PEP-1-HO-1 inhibited cytokine-induced ROS and NO accumulation. • PEP-1-HO-1 suppressed cytokine-induced expression of iNOS, COX-2, and Bax. • PEP-1-HO-1 transduction may be an efficient tool to prevent β-cell destruction

X-prolyl dipeptidyl aminopeptidase gene (pepX) is part of the glnRA operon in Lactobacillus rhamnosus.

Science.gov (United States)

Varmanen, P; Savijoki, K; Avall, S; Palva, A; Tynkkynen, S

2000-01-01

A peptidase gene expressing X-prolyl dipeptidyl aminopeptidase (PepX) activity was cloned from Lactobacillus rhamnosus 1/6 by using the chromogenic substrate L-glycyl-L-prolyl-beta-naphthylamide for screening of a genomic library in Escherichia coli. The nucleotide sequence of a 3.5-kb HindIII fragment expressing the peptidase activity revealed one complete open reading frame (ORF) of 2,391 nucleotides. The 797-amino-acid protein encoded by this ORF was shown to be 40, 39, and 36% identical with PepXs from Lactobacillus helveticus, Lactobacillus delbrueckii, and Lactococcus lactis, respectively. By Northern analysis with a pepX-specific probe, transcripts of 4.5 and 7.0 kb were detected, indicating that pepX is part of a polycistronic operon in L. rhamnosus. Cloning and sequencing of the upstream region of pepX revealed the presence of two ORFs of 360 and 1,338 bp that were shown to be able to encode proteins with high homology to GlnR and GlnA proteins, respectively. By multiple primer extension analyses, the only functional promoter in the pepX region was located 25 nucleotides upstream of glnR. Northern analysis with glnA- and pepX-specific probes indicated that transcription from glnR promoter results in a 2.0-kb dicistronic glnR-glnA transcript and also in a longer read-through polycistronic transcript of 7.0 kb that was detected with both probes in samples from cells in exponential growth phase. The glnA gene was disrupted by a single-crossover recombinant event using a nonreplicative plasmid carrying an internal part of glnA. In the disruption mutant, glnRA-specific transcription was derepressed 10-fold compared to the wild type, but the 7.0-kb transcript was no longer detectable with either the glnA- or pepX-specific probe, demonstrating that pepX is indeed part of glnRA operon in L. rhamnosus. Reverse transcription-PCR analysis further supported this operon structure. An extended stem-loop structure was identified immediately upstream of pepX in the glnA-pep

The beam energy measurement system for the Beijing electron-positron collider

International Nuclear Information System (INIS)

Abakumova, E.V.; Achasov, M.N.; Blinov, V.E.; Cai, X.; Dong, H.Y.; Fu, C.D.; Harris, F.A.; Kaminsky, V.V.; Krasnov, A.A.; Liu, Q.; Mo, X.H.; Muchnoi, N.Yu.; Nikolaev, I.B.; Qin, Q.; Qu, H.M.; Olsen, S.L.; Pyata, E.E.; Shamov, A.G.; Shen, C.P.; Todyshev, K.Yu.

2011-01-01

The beam energy measurement system (BEMS) for the upgraded Beijing electron-positron collider BEPC-II is described. The system is based on measuring the energies of Compton back-scattered photons. The relative systematic uncertainty of the electron and positron beam energy determination is estimated as 2×10 -5 . The relative uncertainty of the beam's energy spread is about 6%.

PepMapper: a collaborative web tool for mapping epitopes from affinity-selected peptides.

Directory of Open Access Journals (Sweden)

Wenhan Chen

Full Text Available Epitope mapping from affinity-selected peptides has become popular in epitope prediction, and correspondingly many Web-based tools have been developed in recent years. However, the performance of these tools varies in different circumstances. To address this problem, we employed an ensemble approach to incorporate two popular Web tools, MimoPro and Pep-3D-Search, together for taking advantages offered by both methods so as to give users more options for their specific purposes of epitope-peptide mapping. The combined operation of Union finds as many associated peptides as possible from both methods, which increases sensitivity in finding potential epitopic regions on a given antigen surface. The combined operation of Intersection achieves to some extent the mutual verification by the two methods and hence increases the likelihood of locating the genuine epitopic region on a given antigen in relation to the interacting peptides. The Consistency between Intersection and Union is an indirect sufficient condition to assess the likelihood of successful peptide-epitope mapping. On average from 27 tests, the combined operations of PepMapper outperformed either MimoPro or Pep-3D-Search alone. Therefore, PepMapper is another multipurpose mapping tool for epitope prediction from affinity-selected peptides. The Web server can be freely accessed at: http://informatics.nenu.edu.cn/PepMapper/

Design for ANL 7 GeV storage ring vacuum system

International Nuclear Information System (INIS)

Wehrle, R.B.; Nielsen, R.W.

1988-01-01

The 7-GeV Advanced Photon Source (APS) design includes a storage ring having a 1060-m circumference with the capability of accommodating 34 insertion devices (ID) and their associated photon beam lines. An additional 35 photon lines can be provided from bending magnets. The vacuum system for the storage ring is designed to maintain a beam-on operating pressure of 1n Torr or less to achieve a positron beam lifetime of approximately 20 hours. The vacuum system and it's current developmental status are described

Renormalization theory of beam-beam interaction in electron-positron colliders

International Nuclear Information System (INIS)

Chin, Y.H.

1989-07-01

This note is devoted to explaining the essence of the renormalization theory of beam-beam interaction for carrying out analytical calculations of equilibrium particle distributions in electron-positron colliding beam storage rings. Some new numerical examples are presented such as for betatron tune dependence of the rms beam size. The theory shows reasonably good agreements with the results of computer simulations. 5 refs., 6 figs

First Evidence of pep Solar Neutrinos by Direct Detection in Borexino

Science.gov (United States)

Bellini, G.; Benziger, J.; Bick, D.; Bonetti, S.; Bonfini, G.; Bravo, D.; Buizza Avanzini, M.; Caccianiga, B.; Cadonati, L.; Calaprice, F.; Carraro, C.; Cavalcante, P.; Chavarria, A.; Chepurnov, A.; D'Angelo, D.; Davini, S.; Derbin, A.; Etenko, A.; Fomenko, K.; Franco, D.; Galbiati, C.; Gazzana, S.; Ghiano, C.; Giammarchi, M.; Goeger-Neff, M.; Goretti, A.; Grandi, L.; Guardincerri, E.; Hardy, S.; Ianni, Aldo; Ianni, Andrea; Korablev, D.; Korga, G.; Koshio, Y.; Kryn, D.; Laubenstein, M.; Lewke, T.; Litvinovich, E.; Loer, B.; Lombardi, F.; Lombardi, P.; Ludhova, L.; Machulin, I.; Manecki, S.; Maneschg, W.; Manuzio, G.; Meindl, Q.; Meroni, E.; Miramonti, L.; Misiaszek, M.; Montanari, D.; Mosteiro, P.; Muratova, V.; Oberauer, L.; Obolensky, M.; Ortica, F.; Otis, K.; Pallavicini, M.; Papp, L.; Perasso, L.; Perasso, S.; Pocar, A.; Quirk, J.; Raghavan, R. S.; Ranucci, G.; Razeto, A.; Re, A.; Romani, A.; Sabelnikov, A.; Saldanha, R.; Salvo, C.; Schönert, S.; Simgen, H.; Skorokhvatov, M.; Smirnov, O.; Sotnikov, A.; Sukhotin, S.; Suvorov, Y.; Tartaglia, R.; Testera, G.; Vignaud, D.; Vogelaar, R. B.; von Feilitzsch, F.; Winter, J.; Wojcik, M.; Wright, A.; Wurm, M.; Xu, J.; Zaimidoroga, O.; Zavatarelli, S.; Zuzel, G.

2012-02-01

We observed, for the first time, solar neutrinos in the 1.0-1.5 MeV energy range. We determined the rate of pep solar neutrino interactions in Borexino to be 3.1±0.6stat±0.3systcounts/(day·100ton). Assuming the pep neutrino flux predicted by the standard solar model, we obtained a constraint on the CNO solar neutrino interaction rate of Mikheyev-Smirnov-Wolfenstein large mixing angle solution to solar neutrino oscillations, these values correspond to solar neutrino fluxes of (1.6±0.3)×108cm-2s-1 and <7.7×108cm-2s-1 (95% C.L.), respectively, in agreement with both the high and low metallicity standard solar models. These results represent the first direct evidence of the pep neutrino signal and the strongest constraint of the CNO solar neutrino flux to date.

Ringing in the new physics: The politics and technology of electron colliders in the United States, 1956--1972

Science.gov (United States)

Paris, Elizabeth

The ``November Revolution'' of 1974 and the experiments that followed consolidated the place of the Standard Model in modern particle physics. Much of the evidence on which these conclusions depended was generated by a new type of tool: colliding beam storage rings, which had been considered physically unfeasible twenty years earlier. In 1956 a young experimentalist named Gerry O'Neill dedicated himself to demonstrating that such an apparatus could do useful physics. The storage ring movement encountered numerous obstacles before generating one of the standard machines for high energy research. In fact, it wasn't until 1970 that the U.S. finally broke ground on its first electron-positron collider. Drawing extensively on archival sources and supplementing them with the personal accounts of many of the individuals who took part, Ringing in the New Physics examines this instance of post-World War II techno-science and the new social, political and scientific tensions that characterize it. The motivations are twofold: first, that the chronicle of storage rings may take its place beside mathematical group theory, computer simulations, magnetic spark chambers, and the like as an important contributor to a view of matter and energy which has been the dominant model for the last twenty-five years. In addition, the account provides a case study for the integration of the personal, professional, institutional, and material worlds when examining an episode in the history or sociology of twentieth century science. The story behind the technological development of storage rings holds fascinating insights into the relationship between theory and experiment, collaboration and competition in the physics community, the way scientists obtain funding and their responsibilities to it, and the very nature of what constitutes ``successful'' science in the post- World War II era.

Proceedings of the workshop on new kinds of positron sources for linear colliders

International Nuclear Information System (INIS)

Clendenin, J.; Nixon, R.

1997-06-01

It has been very clear from the beginning of studies for future linear colliders that the conventional positron source approach, as exemplified by the SLC source, is pushing uncomfortably close to the material limits of the conversion target. Nonetheless, since this type of positron source is better understood and relatively inexpensive to build, it has been incorporated into the initial design studies for the JLC/NLC. New ideas for positron sources for linear colliders have been regularly reported in the literature and at accelerator conferences for at least a decade, and indeed the recirculation scheme associated with the VLEPP design is nearly two decades old. Nearly all the new types of positron sources discussed in this workshop come under the heading of crystals (or channeling), undulators, and Compton. Storage ring and nuclear reactor sources were not discussed. The positron source designs that were discussed have varying degrees of maturity, but except for the case of crystal sources, where proof of principle experiments have been undertaken, experimental results are missing. It is hoped that these presentations, and especially the recommendations of the working groups, will prove useful to the various linear collider groups in deciding if and when new experimental programs for positron sources should be undertaken

Efficient Synthesis of Spirobarbiturates and Spirothiobarbiturates Bearing Cyclopropane Rings by Rhodium(II)-Catalyzed Reactions of Cyclic Diazo Compounds

International Nuclear Information System (INIS)

Wang, Xue; Lee, Yong Rok

2013-01-01

Rhodium(II)-catalyzed reactions of cyclic diazo compounds derived from barbituric acid and thiobarbituric acid with a variety of styrene moieties were examined. These reactions provide rapid synthetic routes to the preparations of spirobarbiturates and spirothiobarbiturates bearing cyclopropane rings

Efficient Synthesis of Spirobarbiturates and Spirothiobarbiturates Bearing Cyclopropane Rings by Rhodium(II)-Catalyzed Reactions of Cyclic Diazo Compounds

Energy Technology Data Exchange (ETDEWEB)

Wang, Xue; Lee, Yong Rok [Yeungnam Univ., Gyeongsan (Korea, Republic of)

2013-06-15

Rhodium(II)-catalyzed reactions of cyclic diazo compounds derived from barbituric acid and thiobarbituric acid with a variety of styrene moieties were examined. These reactions provide rapid synthetic routes to the preparations of spirobarbiturates and spirothiobarbiturates bearing cyclopropane rings.

An Automated 476 MHz RF Cavity Processing Facility at SLAC

CERN Document Server

McIntosh, P; Schwarz, H

2003-01-01

The 476 MHz accelerating cavities currently used at SLAC are those installed on the PEP-II B-Factory collider accelerator. They are designed to operate at a maximum accelerating voltage of 1 MV and are routinely utilized on PEP-II at voltages up to 750 kV. During the summer of 2003, SPEAR3 will undergo a substantial upgrade, part of which will be to replace the existing 358.54 MHz RF system with essentially a PEP-II high energy ring (HER) RF station operating at 476.3 MHz and 3.2 MV (or 800 kV/cavity). Prior to installation, cavity RF processing is required to prepare them for use. A dedicated high power test facility is employed at SLAC to provide the capability of conditioning each cavity up to the required accelerating voltage. An automated LabVIEW based interface controls and monitors various cavity and test stand parameters, increasing the RF fields accordingly such that stable operation is finally achieved. This paper describes the high power RF cavity processing facility, highlighting the features of t...

Single-Particle Dynamics in Electron Storage Rings with Extremely Low Emittance

Energy Technology Data Exchange (ETDEWEB)

Cai, Yunhai; /SLAC

2011-05-31

Electron storage rings are widely used for high luminosity colliders, damping rings in high-energy linear colliders, and synchrotron light sources. They have become essential facilities to study high-energy physics and material and medical sciences. To further increase the luminosity of colliders or the brightness of synchrotron light sources, the beam emittance is being continually pushed downward, recently to the nanometer region. In the next decade, another order of reduction is expected. This requirement of ultra-low emittance presents many design challenges in beam dynamics, including better analysis of maps and improvement of dynamic apertures. To meet these challenges, we have refined transfer maps of common elements in storage rings and developed a new method to compute the resonance driving terms as they are built up along a beamline. The method is successfully applied to a design of PEP-X as a future light source with 100-pm emittance. As a result, we discovered many unexpected cancelations of the fourth-order resonance terms driven by sextupoles within an achromat.

Proline iminopeptidase PepI overexpressing Lactobacillus casei as an adjunct starter in Edam cheese

Science.gov (United States)

Navidghasemizad, Sahar; Takala, Timo M; Alatossava, Tapani; Saris, Per EJ

2013-01-01

In this study the growth of genetically modified Lactobacillus casei LAB6, overexpressing proline iminopeptidase PepI and its capacity to increase free proline was investigated during ripening of Edam cheese. The strain successfully survived 12 weeks of ripening period in cheese. The food-grade plasmid pLEB604, carrying the pepI gene, was stable, and PepI enzyme was active in LAB6 cells isolated at different stages of the ripening process. However, HPLC analyses indicated that Lb. casei LAB6 could not increase the amount of free proline in ripened cheese. PMID:23851577

Movable collimator for positron annihilation imaging device

International Nuclear Information System (INIS)

Thompson, C.J.

1982-01-01

A positron annihilation imaging device has two or more rings of detectors from which three or more slices through the object being scanned can be determined at once. A technique is provided for adjusting the slice widths. One slice may be imaged by all detectors in adjacent planes simultaneously, and reconstructed as if all detectors were in the same plane. The single slice facility is provided without the necessity of rotating the detector array or moving it in any way during data collection, allowing the possibility of doing physiologically gated imaging of a single slice

Positron-containing systems and positron diagnostics

International Nuclear Information System (INIS)

1978-01-01

The results of the experimental and theoretical investigations are presented. Considered are quantum-mechanical calculations of wave functions describing the states of positron-containing atomic systems and of cross-sections of the processes characterizing different interactions, and also the calculations of the behaviour of positrons in gases in the presence of an electric field. The results of experimental tests are presented by the data describing the behaviour of positrons and positronium in liquids, polymers and elastomers, complex oxides and in different solids. New equipment and systems developed on the basis of current studies are described. Examined is a possibility of applying the methods of model and effective potentials for studying the bound states of positron systems and for calculating cross-sections of elementary processes of elastic and inelastic collisions with a positron involved. The experimental works described indicate new possibilities of the positron diagnosis method: investigation of thin layers and films of semiconductor materials, defining the nature of chemical bonds in semiconductors, determination of the dislocation density in deformed semiconductors, derivation of important quantitative information of the energy states of radiation defects in them

Beam-beam force and storage ring parameters

International Nuclear Information System (INIS)

Herrera, J.C.

1979-01-01

The fundamental aspects of the beam--beam force as it occurs in Intersecting Storage Rings are reported. The way in which the effect of the beam--particle electromagnetic force (weak--strong interaction) is different in the case of unbunched proton beams which cross each other at an angle (as in the ISR and in ISABELLE) is shown, as compared to the case of electron--positron beams where bunches collide head-on

Design and mechanism of action of a novel bacteria-selective antimicrobial peptide from the cell-penetrating peptide Pep-1

International Nuclear Information System (INIS)

Zhu, W.L.; Lan Hongliang; Park, Il-Seon; Kim, Jae Il; Jin, H.Z.; Hahm, Kyung-Soo; Shin, S.Y.

2006-01-01

Here, we report the successful design of a novel bacteria-selective antimicrobial peptide, Pep-1-K (KKTWWKTWWTKWSQPKKKRKV). Pep-1-K was designed by replacing Glu-2, Glu-6, and Glu-11 in the cell-penetrating peptide Pep-1 with Lys. Pep-1-K showed strong antibacterial activity against reference strains (MIC = 1-2 μM) of Gram-positive and Gram-negative bacteria as well as against clinical isolates (MIC = 1-8 μM) of methicillin-resistant Staphylococcus aureus and multidrug-resistant Pseudomonas aeruginosa. In contrast, Pep-1-K did not cause hemolysis of human erythrocytes even at 200 μM. These results indicate that Pep-1-K may be a good candidate for antimicrobial drug development, especially as a topical agent against antibiotic-resistant microorganisms. Tryptophan fluorescence studies indicated that the lack of hemolytic activity of Pep-1-K correlated with its weak ability to penetrate zwitterionic phosphatidylcholine/cholesterol (10:1, w/w) vesicles, which mimic eukaryotic membranes. Furthermore, Pep-1-K caused little or no dye leakage from negatively charged phosphatidylethanolamine/phosphatidylglycerol (7:3, w/w) vesicles, which mimic bacterial membranes but had a potent ability to cause depolarization of the cytoplasmic membrane potential of intact S. aureus cells. These results suggested that Pep-1-K kills microorganisms by not the membrane-disrupting mode but the formation of small channels that permit transit of ions or protons but not molecules as large as calcein

21 CFR 870.3800 - Annuloplasty ring.

Science.gov (United States)

2010-04-01

...) Identification. An annuloplasty ring is a rigid or flexible ring implanted around the mitral or tricuspid heart valve for reconstructive treatment of valvular insufficiency. (b) Classification. Class II (special...

Power Extension Package (PEP) system definition extension, orbital service module systems analysis study. Volume 9: PEP design, development and test plans

Science.gov (United States)

1979-01-01

A plan for the production of two PEP flight systems is defined. The task's milestones are described. Provisions for the development and assembly of new ground support equipment required for both testing and launch operations are included.

BioPepDB: an integrated data platform for food-derived bioactive peptides.

Science.gov (United States)

Li, Qilin; Zhang, Chao; Chen, Hongjun; Xue, Jitong; Guo, Xiaolei; Liang, Ming; Chen, Ming

2018-03-12

Food-derived bioactive peptides play critical roles in regulating most biological processes and have considerable biological, medical and industrial importance. However, a large number of active peptides data, including sequence, function, source, commercial product information, references and other information are poorly integrated. BioPepDB is a searchable database of food-derived bioactive peptides and their related articles, including more than four thousand bioactive peptide entries. Moreover, BioPepDB provides modules of prediction and hydrolysis-simulation for discovering novel peptides. It can serve as a reference database to investigate the function of different bioactive peptides. BioPepDB is available at http://bis.zju.edu.cn/biopepdbr/ . The web page utilises Apache, PHP5 and MySQL to provide the user interface for accessing the database and predict novel peptides. The database itself is operated on a specialised server.

Homotopic non-local regularized reconstruction from sparse positron emission tomography measurements

International Nuclear Information System (INIS)

Wong, Alexander; Liu, Chenyi; Wang, Xiao Yu; Fieguth, Paul; Bie, Hongxia

2015-01-01

Positron emission tomography scanners collect measurements of a patient’s in vivo radiotracer distribution. The system detects pairs of gamma rays emitted indirectly by a positron-emitting radionuclide (tracer), which is introduced into the body on a biologically active molecule, and the tomograms must be reconstructed from projections. The reconstruction of tomograms from the acquired PET data is an inverse problem that requires regularization. The use of tightly packed discrete detector rings, although improves signal-to-noise ratio, are often associated with high costs of positron emission tomography systems. Thus a sparse reconstruction, which would be capable of overcoming the noise effect while allowing for a reduced number of detectors, would have a great deal to offer. In this study, we introduce and investigate the potential of a homotopic non-local regularization reconstruction framework for effectively reconstructing positron emission tomograms from such sparse measurements. Results obtained using the proposed approach are compared with traditional filtered back-projection as well as expectation maximization reconstruction with total variation regularization. A new reconstruction method was developed for the purpose of improving the quality of positron emission tomography reconstruction from sparse measurements. We illustrate that promising reconstruction performance can be achieved for the proposed approach even at low sampling fractions, which allows for the use of significantly fewer detectors and have the potential to reduce scanner costs

Status report of PEP-4

International Nuclear Information System (INIS)

Kamae, Tuneyoshi

1982-01-01

The present status of PEP-4 is reported. The cosmic ray test of a TPC without magnetic field was done in July, 1981, and tracks were observed on the first day of the test. The entire PEP-4 detector was tested with 3.9 kG magnetic field in November, 1981, and various trigger configurations were tested. The TPC performed well during the test, and a preliminary analysis gave an encouraging position resolution which is expected to be improved with the correction for various non-uniformity and by refining the fitting procedure. Furthermore, the detection efficiency of the muon chamber was about 99 %. In November and December, 1981, the cosmic ray test of the hexagonal calorimeter was carried out. The performance was just as expected. Noise did not pose any problem, and the peak of the Fourier coefficient gave a nice overall calibration of the calorimeter. There are some problems to be solved in future. With the TPC, the impurities in the gas, the electronic noise, the hooks and the magnetic coil should be improved. In addition, there are some problems with the inner drift chamber, the hexagonal calorimeter and the relativistic rise measured by the TPC. The very recent results with the first e + e - beam obtained in February, 1982, are briefly reported, although the events have not been fully analyzed. (Ito, K.)

Topology in quantum states. PEPS formalism and beyond

Energy Technology Data Exchange (ETDEWEB)

Aguado, M [Max-Planck-Institut fuer Quantenoptik. Hans-Kopfermann-Str. 1. D-85748 Garching (Germany); Cirac, J I [Max-Planck-Institut fuer Quantenoptik. Hans-Kopfermann-Str. 1. D-85748 Garching (Germany); Vidal, G [School of Physical Sciences. University of Queensland, Brisbane, QLD, 4072 (Australia)