Test of Time-Reversal Invariance in Proton-Deuteron Scattering at COSY

We propose to perform a novel (P-even, T-odd) null test of time-reversal invariance to an experimental accuracy of 10-6. The parity conserving time-reversal violating observable is the total cross-section asymmetry Ay,xz. The measurement is planned as an internal target transmission experiment at the cooler synchrotron COSY. Ay,xz is measured using a polarized proton beam with an energy of 135 MeV and a tensor polarized deuteron target. Since the experiment has to be staged, with the current request we ask for the two weeks of beam time by the end of 2012 for studies of bunched beam life time

Beam Request Spin-Filtering Studies at COSY

Summary of experiment: We report on the progress of the PAX experimental program since the last PAC meeting. During two blocks of each three weeks beam development intercepted by two weeks of maintenance, systematic machine studies have been carried out. An effective procedure for setting up the machine with the low-β section and a target cell at the new PAX-IP in order to achieve high beam lifetimes has been developed. The effect of flow-limiters and one NEG-pump on the beam lifetime has been studied, as well as the effect of different beam emittances and beam intensities on the beam lifetime. Even though by increasing the beam emittance a reproducible maximum for the beam lifetime was achievable, no effect of the beam intensity was seen and therefore no clear observation of the so-called Touschek-effect was possible. Nevertheless, we learned how to gain a sufficient beam lifetime for spin-filtering studies at COSY and apply for 3 weeks of beam development followed by 4 weeks of beam time

Status Report and Beam-Time Request for COSY experiment #199 Spin–Filtering Studies at COSY

We report on the progress of the PAX experimental programme since the last PAC meeting. During summer shutdown 2009 four new quadrupole magnets and a modified vacuum system have been installed into the COSY ring to form a section with low β functions. With the successful commissioning of this low-β insertion in January 2010 it has also been discovered that intra-beam scattering effects are likely limiting the beam lifetime. In order to get these effects under control and to improve the lifetime, to commission a new detection system, and to finally perform a first series of spin–filtering measurements with transverse polarisation, we request ten weeks of beam time. Content

Spin-Filtering Studies at COSY

We propose to use an internal polarised target in the COSY ring to determine the polarisation build–up in a proton beam. Spin–filtering experiments at COSY would provide the necessary data to test our present understanding of spin–filtering processes in storage rings. Measurements of the polarisation build–up of stored protons are crucial to progress towards the PAX goal to eventually produce stored polarised antiproton beams. The availability of intense stored beams of polarised antiprotons will provide access to a wealth of single– and double–spin observables, opening a new window on QCD spin physics. It is planned to realise this experimental programme at the new Facility for Antiproton and Ion Research (FAIR) at GSI in Darmstadt, Germany. A recent experiment at COSY revealed that e~p spin–flip cross sections are too small to cause a detectable depolarisation of a stored proton beam. This measurement rules out a proposal to use polarised electrons to polarise a proton beam by ~ep spin–flip interactions. Thus, our approach to provide a beam of polarised protons is based on spin–filtering using an internal polarised gas target. In total 22 weeks of beam time are needed to complete the experimental program at COSY. We now ask for two weeks of beam time for commissioning of the low–β section and measuring the machine acceptance

Measurement of Spin Observables in the ~p ~d Breakup Reaction

We update our Letter-of-Intent 202 for Measurement of Spin Observables in the ~p ~d Breakup Reaction. An estimate of the overall beam time needed for completing the measurements is specied and a timeline in view of the planned PAX experiments is presented. The proposal aims at a study of the three nucleon continuum in proton deuteron breakup reactions, between 30 and 50 MeV proton beam energies, an energy range where there have been few and limited measurements. The large coverage of the PAX detection setup and the energy range chosen will provide essential new data intended as a laboratory for chiral eective eld theory, the modern theory for nuclear forces relevant at low and intermediate energies. Vector and tensor analyzing powers and spin correlation coecients will be measured and evaluated over large kinematical areas in the ve parameter phase space of the nal state containing three nucleons. For the analysis the sampling method will be used, a technique developed specically for the complex analysis of three particle nal states, providing a direct comparison between experiment and theory

Characterization of the New n TOF Neutron Beam: Fluence, Profile and Resolution

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The Role of Fe and Ni for S-process Nucleosynthesis and Innovative Nuclear Technologies

The accurate measurement of neutron capture cross sections of all Fe and Ni isotopes is important for disentangling the contribution of the s-process and the r-process to the stellar nucleosynthesis of elements in the mass range 60 < A < 120. At the same time, Fe and Ni are important components of structural materials and improved neutron cross section data is relevant in the design of new nuclear systems. With the aim of obtaining improved capture data on all stable iron and nickel isotopes, a program of measurements has been launched at the CERN Neutron Time of Flight Facility n_TOF

Improved Neutron Capture Cross Section Measurements with the n_TOF Total Absorption Calorimeter

The n_TOF collaboration operates a Total Absorption Calorimeter (TAC) [1] for measuring neutron capture cross-sections of low-mass and/or radioactive samples. The results obtained with the TAC have led to a substantial improvement of the capture cross sections of (237)Np and (240)Pu [2]. The experience acquired during the first measurements has allowed us to optimize the performance of the TAC and to improve the capture signal to background ratio, thus opening the way to more complex and demanding measurements on rare radioactive materials. The new design has been reached by a series of detailed Monte Carlo simulations of complete experiments and dedicated test measurements. The new capture setup will be presented and the main achievements highlighted

First

Most elements heavier than iron have been generated in the stellar media by means of neutron capture reactions, approximately half are produced by the slow neutron capture or s-process. Radiative neutron capture cross section measurements are of fundamental importance for the study of this mechanism. In this contribution we present a brief summary on the measurement and results for the 80Se(n,γ) cross-section. The experiment was carried out at CERN n_TOF EAR1 via the time of flight (ToF) technique, using four C6D6 scintillation detectors with very fast response. More than a hundred new resonances have been analyzed for the first time with a high accuracy. The MACS obtained at kT = 8 keV is 36% smaller than the recommended value in KADo-NiS. Some of the astrophysical implications of this result are elucidated in this contribution