The feasibility of the TRIC experiment at COSY

Abstract

For the Time Reversal Invariance experiment at COSY (TRIC) that had been proposed at the Forschungszentrum Jülich a novel technique for measuring total cross sections in internal experiments was developed and the achievable precision of this measuring technique was tested. The experimental idea constitutes a true P-even T-odd null test of TRI. In order to compare to the theoretical upper bound from edm measurements (Haxton and Höring, Nucl Phys A560:469, 1993), the TRI violating observable A y,xz in proton-deuteron forward scattering has to be measured with an accuracy of 10 −6 . An internal TRI experiment can determine the total cross section via the optical theorem by measuring the forward scattering amplitude. In contrast to external experiments, the only calibrated device that is needed is a precise beam current transformer (BCT). The feasibility of an internal TRI experiment was tested at COSY in a measurement of A y,y in p-p scattering, since these values are known. The analysis of the data showed the presence of unexpected large 1/ f noise contributions, which eventually reduced the achievable accuracy by a factor 3. The origin of the 1/ f noise was traced and found to be the Barkhausen noise from the

The legacy of the experimental hadron physics programme at COSY

“…The obvious disadvantage of this spin-filtering method is that, unless σ 1 /σ 0 is very large, the beam intensity would be much reduced before a significant polarization could be built up. There are some similarities here with the measurements of the beam lifetime discussed in connection with the TRIC experiment, the difference being that in the study of A y,y the beam was initially polarized [60].…”

“…The obvious disadvantage of this spin-filtering method is that, unless σ 1 /σ 0 is very large, the beam intensity would be much reduced before a significant polarization could be built up. There are some similarities here with the measurements of the beam lifetime discussed in connection with the TRIC experiment, the difference being that in the study of A y,y the beam was initially polarized [60]. A proof-of-principle experiment was carried out at the Test Storage Ring at Heidelberg using 23 MeV protons passing through a cell filled with transversally polarized hydrogen supplied by an atomic beam source.…”

Test of Time-Reversal Invariance at COSY

“…A detailed discussion of the results obtained can be found in Ref. [11]. Three main conclusions were drawn:…”

Spin physics at COSY and beyond

“…The effects of the breaking of time-reversal invariance can be searched for simultaneously in measurements of total cross sections using a beam-current transformer (BCT), and studies of differential observables using the PAX detection system. A status report about an earlier preparatory experiment carried out at COSY is given in [19]. The test beam time (Oct. 2006) has shown that the accuracy of the standard BCT is not sufficient to reach the necessary precision of 10 −6 in a timereversal non-invariance test.…”