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 Julich 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 Horing, Nucl Phys A560:469, 1993), the TRI violating observable Ay,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 Ay,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 ferrite-core of the BCT. A global weighted fitting technique based on a modified Wiener-Khinchin method was applied to suppress the influence of the 1/f noise.