Dresden 2013 – scientific programme

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HK: Fachverband Physik der Hadronen und Kerne

HK 78: Fundamentale Symmetrien

HK 78.6: Talk

Thursday, March 7, 2013, 18:30–18:45, HSZ-401

Background studies for the spectrometer aSPECT — •Romain Maisonobe — Institut Laue-Langevin, Grenoble, France

The retardation spectrometer aSPECT was built to determine the electron-antineutrino angular correlation coefficient a in neutron beta-decay with unprecedented accuracy Δa/a≈0.3%, by measuring the proton recoil spectrum. The a coefficient can be used to derive the ratio λ=g_A/g_V of the weak coupling constants g_A and g_V and to test the unitarity of the CKM matrix, or to derive limits for physics beyond the Standard Model. The attempted precision requires a good understanding of the background.

In 2012, the spectrometer was installed offline (without neutron beam) in order to perform high-voltage tests, to optimize operation parameters of the spectrometer (see talk of Alexander Wunderle), and to study the background behavior for different electrode voltage settings and vacuum conditions. A beta source (activated gold foil) was used to simulate rest-gas ionization by electrons from neutron decay. We present these background studies and the conclusions for the measurement of a.

A new beamtime with aSPECT is scheduled for spring 2013.