Tübingen 2003 – scientific programme

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HK: Physik der Hadronen und Kerne

HK 2: Kernphysik/Spektroskopie I

HK 2.5: Talk

Monday, March 17, 2003, 17:15–17:30, A

³He magnetometer for neutron EDM experiments — •Stefan Baeßler¹, Werner Heil¹, Yuri Sobolev¹, Vladimir Lobashev², Wolfgang Kilian³, Herbert Rinneberg³ und Frank Seifert³ — ¹Institut für Physik, Universität Mainz — ²Physikalisch-Technische Bundesanstalt, Berlin — ³Institute of Nuclear Research, Moscow, Russia

We report on a ³He-magnetometer capable of detecting tiny magnetic field fluctuations of less than 10⁻¹⁴ Tesla in experiments which measure the electric dipole moment (EDM) of the neutron. It is based both on the Ramsey technique of separated oscillating fields and on the detection of the spin precession signal by means of low T_c-SQUIDS. The nuclear spin-polarized ³He gas is polarized by means of metastable optical pumping and stored in two flat cylindrical vessels of V∼ 4 liter in a sandwich type arrangement around a twin-chamber type storage bottle for ultra-cold neutrons.

A numerical analysis was made which shows that systematic errors correlated to the switching of the applied electric field, which may cause a finite false neutron EDM value, can be traced down to d_EDM∼ 10⁻²⁸ e cm. This is just the order of sensitivity which is needed by recently proposed experiments which aim to measure the neutron EDM at new powerful UCN sources, like at the Paul-Scherrer-Institute, Villigen or the FRM 2-reactor, Munich.