PERFORMANCE OF THE SCINTILLATION PROFILE MONITOR 2011IN THE COSY SYNCHROTRON

Residual gas scintillation is used for measuring profile of the proton beam circulating in the COSY synchrotron. The problem of low rate of scintillation events detected by a multichannel photomultiplier is coped with byinjecting small amounts of pure nitrogen into the vacuum chamber of the Scintillation Profile Monitor (SPM). This leads to a temporary local pressure bump of no more than an order of magnitude. A commercially available piezoelectric dosing valve allows good control over the amplitude and duration of the pressure bump. Since the average pressure in the machine is hardly changed, the method is fully compatible with experiment operation.This approach offers a robust and inexpensive way to measure the beam profile. The design of the SPM is discussed. The latest measurement results and comparison to the ionization profile monitor data is presented

PROGRESS WITH THE SCINTILLATION PROFILE MONITOR AT COSY

After successful demonstration measurements with the Scintillation Profile Monitor (SPM) at COSY, a dedicated vacuum chamber with two vacuum windows and supporting vacuum ports was installed in the COSYsynchrotron. The chamber is blackened inside to suppress light reflection. Since residual gas pressure is too low to support reliable profile measurements based on beam induced scintillation, a piezo-electric dosing valve wasinstalled allowing fast injections of defined amount of nitrogen. A 32-channel photomultiplier is used to detect light. Beam profile measurements and first experience are reported

PERFORMANCE OF THE SCINTILLATION PROFILE MONITOR IN THE COSY SYNCHROTRON

Residual gas scintillation is used for measuring profile of the proton beam circulating in the COSY synchrotron. The problem of low rate of scintillation events detected by a multichannel photomultiplier is coped with by injecting small amounts of pure nitrogen into the vacuum chamber of the Scintillation Profile Monitor (SPM). This leads to a temporary local pressure bump of no more than an order of magnitude. A commercially available piezoelectric dosing valve allows good control over the amplitude and duration of the pressure bump. Since the average pressure in the machine is hardly changed, the method is fully compatible with experiment operation. This approach offers a robust and inexpensive way to measure the beam profile. The design of the SPM is discussed. The latest measurement results and comparison to the ionization profile monitor data is presented

Numerical comparative study of BPM designs for the HESR at FAIR

The Institute of Nuclear Physics 4(IKP-4) of the Research Center Jülich (FZJ) is in charge of building and commissioning the High Energy Storage Ring (HESR) within the international Facility for Antiproton and Ion Research (FAIR) at Darmstadt. Simulations and numerical calculations were performed to characterize the beam position pickup design that is currently envisaged for the HESR, i.e. a diagonally cut cylindrical pickup. The behavior of the electrical equivalent circuit has been investigated with emphasis on capacitive cross coupling. Based on our findings, performance increasing changes to the design were introduced. A prototype of the BPM pickup was constructed and tested on a dedicated test bench. Preliminary results are presented. Another proposed design was characterized and put into comparison, as higher signal levels and higher position sensitivity are expected. That is a symmetrical straight four-strip geometry. Additionally an extensive study was conducted to quantify the effect of manufacturing tolerances. Driven by curiosity an eight-strip pickup design was considered, which would allow for beam size measurements, utilizing the non-linearity

Beam Diagnostics for the High Energy Storage Ring at FAIR

Numerous beam diagnostics systems, with the BPM system considered the most important one, are envisaged for the High Energy Storage Ring (HESR) within the FAIR Project. The BPM design, the corresponding test bench, HESR BLM studies at COSY, status of the ionization profile monitor and other subsystems are presented

Injection Kicker for HESR at FAIR using Semi-Conductor Switches

The High Energy Storage Ring (HESR) is a part of the future Facility for Antiproton and Ion Research (FAIR) in Darmstadt. The ring is used for hadron physics experiments with a pellet target and the PANDA detector, and will supply antiprotons of momenta from 1.5 GeV/c to 15 GeV/c. To cover the whole energy range a flexible adjustment of transition energy and the corresponding gamma-t value is foreseen. For Injection and Accumulation of Antiprotons delivered from the CR at a momentum of 3.8 GeV/c (gamma=4.2), the HESR optics will be tuned to gamma-t=6.2. For deceleration down to a momentum of 1.5 GeV/c this optic is suitable as well. Stochastic cooling at an intermediate energy is required to avoid beam losses caused by adiabatic growth of the beam during deceleration. For acceleration to 8 GeV/c (gamma=8.6) the optics will be changed after accumulation of the antiproton beam to gamma-t=14.6. For momenta higher than 8 GeV/c the beam will be debunched at 8 GeV/c, optics will be changed to gamma-t=6.2, and after adiabatic rebunching the beam will be accelerated to 15 GeV/c (gamma=16). Simulations show the feasibility of the described procedures with practically no beam losses

A High-Density Polarized 3He Gas–Jet Target for Laser–Plasma Applications

A laser-driven spin-polarized 3He2+-beam source for nuclear–physics experiments and for the investigation of polarized nuclear fusion demands a high-density polarized 3He gas-jet target. Such a target requires a magnetic system providing a permanent homogeneous holding field for the nuclear spins plus a set of coils for adjusting the orientation of the polarization. Starting from a transport vessel at a maximum pressure of 3 bar, the helium gas is compressed for a short time and can be injected into a laser–interaction chamber through a non-magnetic opening valve and nozzle, thus forming jets with densities of about a few 1019 cm−3 and widths of about 1 mm. The target comprises a 3D adjustment system for precise positioning of the jet relative to the laser focus. An auxiliary gas system provides remote target operation and flushing of the gas lines with Ar gas, which helps to reduce polarization losses. The design of the target, its operation procedures and first experimental results are presented

The KOALA experiment for (anti)proton–proton elastic scattering

The KOALA experiment measures the differential cross section of (anti)proton–proton elastic scattering over a wide range of four-momentum transfer squared from 0.0008 to 0.1 (GeV/c)2. These data are essential input for the PANDA experiment to reach the desired absolute precision for the integrated luminosity determination. The KOALA experiment is based on fixed target kinematics and uses an internal hydrogen cluster jet target. The wide range of is achieved by measuring the total kinetic energy of the recoil protons near 90. The recoil detector consists of silicon and germanium single-sided strip sensors with an energy resolution of approximately 20 keV and 30 keV (FWHM), respectively. A forward detector consisting of two layers of plastic scintillators measures the elastically scattered beam particles in the forward direction close to the beam axis. By requiring a coincidence of the forward detector with the recoil detector, the large background at small recoil angles is suppressed, thereby improving the identification of elastic scattering events in the low range. The KOALA setup has been installed and commissioned with proton beam at COSY in order to validate the detector by measuring the proton–proton elastic scattering. The results from this commissioning are presented here

A polarized 3He Target for the Exploration of Spin Effects in Laser-induced Plasmas

In order to investigate the polarization degree of laser-accelerated 3He ions from a polarized 3He gas-jet target, several challenges have to be overcome. One of these is the development of an appropriate polarized 3He gas-jet target. Since our experiments are carried out at the PHELIX Petawatt Laser Facility, GSI Darmstadt, the layout of the set-up has to cope with the available space within the PHELIX target chamber. The essential components of such a layout are a magnetic holding field for storing polarized 3He gas inside the vacuum chamber for many hours, the gas-jet source for providing the desired laser target, and finally, a polarimeter for measuring the spin-polarization degree of laser-accelerated 3He2+ ions