The PAX (Polarized Antiproton eXperiment) collaboration aims to polarise antiproton beams stored in ring by means of spin-filtering. The experimental setup is based on a polarised internal gas ...target, surrounded by a detection system for the measurement of spin observables. In this report, we present results from the commission of the PAX target (atomic beam source, openable cell, and polarimeter).
A Polarized Internal gas Target (PIT) has been developed for the ANKE spectrometer at COSY. After its first installation at the ANKE target position in summer 2005, commissioning studies were carried ...out. In March 2006, first single polarization measurements with the polarized hydrogen beam from an Atomic Beam Source (ABS) were performed. The beam was injected into a storage cell made from aluminum foil. The data analysis showed that the events from the extended gas target can be clearly identified in the ANKE forward detection system. Using unpolarized nitrogen, the background from the cell walls could be determined as well. The thickness of the gas in the storage cell with the hydrogen atoms in hyperfinestate |1⟩ was measured as 2×1013 atoms/cm2. The ABS jet target thickness was 1.5×1011 atoms/cm2. In November 2006, the commissioning of a Silicon Tracking Telescope (STT) was successfully finished. In the following beam time in January 2007, a new storage cell from aluminum coated with teflon was used together with the STT. The Lamb-shift polarimeter (LSP) was mounted below the target chamber to allow for online tuning of the transition units and monitoring of the ABS jet polarization. A first double-polarized experiment was performed, the results will be presented.
The polarized H and D atomic beam source for ANKE at COSY-Jülich Mikirtychyants, M.; Engels, R.; Grigoryev, K. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
09/2013, Letnik:
721
Journal Article
Recenzirano
A polarized atomic beam source was developed for the polarized internal storage-cell gas target at the magnet spectrometer ANKE of COSY-Jülich. The intensities of the beams injected into the storage ...cell, measured with a compression tube, are 7.5×1016 hydrogen atoms/s (two hyperfine states) and 3.9×1016 deuterium atoms/s (three hyperfine states). For the hydrogen beam the achieved vector polarizations are pz≈±0.92. For the deuterium beam, the obtained combinations of vector and tensor (pzz) polarizations are pz≈±0.90 (with a constant pzz≈+0.86), and pzz=+0.90 or pzz=−1.71 (both with vanishing pz). The paper includes a detailed technical description of the apparatus and of the investigations performed during the development. This source has been very successfully used for single and double polarization measurements at ANKE as well as for studies of the polarization of recombining hydrogen molecules.
PROFIBUS, being a national German (DIN 19245) and an European (EN 50170) standard, has become the most widely accepted modern fieldbus technology in Europe. It is expected to rake a similar role on ...the world market, since the IEC standardisation efforts for a common international fieldbus failed recently. A major reason for its success is the technological and functional scalability based on a common core. Now, a wide range of PLCs as well as low cost process I/O is available (also from leading manufacturers like Siemens) which enable easy interfacing. ZEL, the central electronics facility of Forschungszentrum Julich, has decided to use predominantly industrial components (PLCs, I/Os, etc.) in the front end of slow control systems for physics experiments. Interfacing of these devices is accomplished by PROFIBUS controllers, that have been developed for PCI and CompactPCI with device drivers for Linux and LynxOS. Front end PROFIBUS controllers have been developed for integrating dedicated devices. On the base of two case studies-a nuclear experiment and a neutron scattering experiment-the paper describes this approach. Design of the PROFIBUS hardware and software as well as performance results are presented.
The occupation numbers of the individual hyperfine substates in a beam of hydrogen or deuterium atoms are measured with a Lamb-shift polarimeter. Therefore, the nuclear polarization of an atomic beam ...can be determined with high precision of about
0.5
% within 20
s. The measurements are carried out with the atomic beam source for the internal polarized storage-cell gas target of ANKE (
I
∼
7
×
10
16
atoms/s). The polarization of a slow (500–2000
eV) ion beam with currents higher than 1
nA can be measured as well. When the intensity of the atomic beam is reduced by a factor of 100, the Lamb-shift polarimeter still provides a precise measurement with an error of about 2% within 30
s. Thus, it is thought possible to determine the nuclear polarization of the atomic gas inside the storage cell, when a sample of these atoms effuse into the Lamb-shift polarimeter through a sample tube.
First, results obtained with a simple Teflon cell, a new ionizer with an internal getter pump, a newly designed Wien filter and a larger photomultiplier are presented. Planned studies to optimize the polarization measurement are discussed as well.
For future few-nucleon interaction studies with polarized beams and targets at COSY-Julich, a polarized internal storage-cell gas target was implemented at the magnet spectrometer ANKE in summer ...2005. First commissioning of the polarized Atomic Beam Source (ABS) at ANKE was carried out and some improvements of the system have been done. Storage-cell tests to determine the COSY beam dimensions have been performed. Electron cooling combined with stacking and stochastic cooling have been studied. Experiments with N2 gas in the storage cell to simulate the background produced by beam interaction with the aluminum cell walls were performed to investigate the beam heating by the target gas. The analysis of the 'd-vector ''p-vector ''- > 'dp and 'd-vector ''p-vector ''- > '(dpsp)pi0 reactions showed that events from the extended target can be clearly identified in the ANKE detector system.The polarization of the atomic beam of the ABS, positioned close to the strong dipole magnet D2 of ANKE, was tuned with a Lamb-shift polarimeter (LSP) beneath the target chamber. With use of the known analyzing powers of the quasi-free np'- > 'dpi0 reaction, the polarization in the storage cell was measured to be Qy = 0.79+/-0.07 in the vertical stray field of the D2 magnet acting as a holding field. The achieved target thickness was 2X1013 atoms/cm2 for one hyperfine state populated in the ABS beam only. With a COSY beam intensity of 6X109 stored polarized deuterons in the ring, the luminosity for double polarized experiments was 1X1029 cm-2 s-1.
The PAX Collaboration has successfully performed a spin-filtering experiment with protons at the COSY-ring. The measurement allowed the determination of the spin-dependent polarizing cross section, ...that compares well with the theoretical prediction from the nucleonanucleon potential. The test confirms that spin-filtering can be adopted as a method to polarize a stored beam and that the present interpretation of the mechanism in terms of the protonaproton interaction is correct. The outcome of the experiment is of utmost importance in view of the possible application of the method to polarize a beam of stored antiprotons.
The polarized H and D atomic beam source for ANKE at COSY-JA14lich Mikirtychyants, M; Engels, R; Grigoryev, K ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
09/2013, Letnik:
721
Journal Article
Recenzirano
A polarized atomic beam source was developed for the polarized internal storage-cell gas target at the magnet spectrometer ANKE of COSY-JA14lich. The intensities of the beams injected into the ...storage cell, measured with a compression tube, are 7.5A10167.5A1016 hydrogen atoms/s (two hyperfine states) and 3.9A10163.9A1016 deuterium atoms/s (three hyperfine states). For the hydrogen beam the achieved vector polarizations are pzaA-0.92pzaA-0.92. For the deuterium beam, the obtained combinations of vector and tensor (pzzpzz) polarizations are pzaA-0.90pzaA-0.90 (with a constant pzza+0.86pzza+0.86), and pzz=+0.90pzz=+0.90 or pzz=a1.71pzz=a1.71 (both with vanishing pzpz). The paper includes a detailed technical description of the apparatus and of the investigations performed during the development. This source has been very successfully used for single and double polarization measurements at ANKE as well as for studies of the polarization of recombining hydrogen molecules.
In a previous publication, measurements of the depolarization of a stored proton beam by interaction with a co-propagating unpolarized electron beam at low relative energy have been presented and an ...upper limit of about 3 ×107 b for the electron–proton spin-flip cross-section was determined. A refined analysis presented in this paper reduces the previous upper limit by a factor of three by the introduction of a new procedure that also makes use of non-identified particles.
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