An Improved Neutron Electric Dipole Moment Experiment

A new measurement of the neutron EDM, using Ramsey's method of separated oscillatory fields, is in preparation at the new high intensity source of ultra-cold neutrons (UCN) at the Paul Scherrer Institute, Villigen, Switzerland (PSI). The existence of a non-zero nEDM would violate both parity and time reversal symmetry and, given the CPT theorem, might lead to a discovery of new CP violating mechanisms. Already the current upper limit for the nEDM (|d_n|<2.9E-26 e.cm) constrains some extensions of the Standard Model. The new experiment aims at a two orders of magnitude reduction of the experimental uncertainty, to be achieved mainly by (1) the higher UCN flux provided by the new PSI source, (2) better magnetic field control with improved magnetometry and (3) a double chamber configuration with opposite electric field directions. The first stage of the experiment will use an upgrade of the RAL/Sussex/ILL group's apparatus (which has produced the current best result) moved from Institut Laue-Langevin to PSI. The final accuracy will be achieved in a further step with a new spectrometer, presently in the design phase.Comment: Flavor Physics & CP Violation Conference, Taipei, 200

GLM analysis of time resolved NIRS data of motor activation during different motor tasks

The hemodynamic response to motor activation was investigated by time-resolved NIRS in healthy subjects and patients with unilateral impairment in motor ability. Healthy subjects performed a simple and a complex finger movement task, patients a handgrip task. A General Linear Model approach (GLM) was applied during NIRS data processing. In general, compared to the integral (continuous wave signal), higher significance of activation was found for the variance signal that selectively represents changes in the deep compartment. A discussion of GLM results with respect to task complexity and difficulty is provided

Additional results from the first dedicated search for neutron mirror neutron oscillations

The existence of a mirror world holding a copy of our ordinary particle spectrum could lead to oscillations between the neutron(n) and its mirror partner(n'). Such oscillations could manifest themselves in storage experiments with ultracold neutrons whose storage lifetime would depend on the applied magnetic field. Here, extended details and measurements from the first dedicated experimental search for nn' oscillations published in[G.Ban,K.Bodek,M.Daum,R.Henneck,S.Heule,M.Kasprzak, N. Khomutov,K.Kirch,S.Kistryn,A.Knecht,P.Knowles,M.Ku´ zniak,T.Lefort,A.Mtchedlishvili,O.Naviliat-Cuncic,C.Plonka,G.Quemener,M.Rebetez,D.Rebreyend,S.Roccia,G.Rogel,M.Tur,A.Weis,J.Zejma,G.Zsigmond, Direct experimental limit on neutron mirror–neutron oscillations, Phys.Rev.Lett. 99 (2007)161603]will be presented, focussing on a possible dependence of the UCN counts on the magnetic field and its direction. However, at present no significant change in the averaged UCN counts with respect to the applied magnetic field has been found.status: publishe

Additional results from the first dedicated search for neutron–mirror–neutron oscillations

The existence of a mirror world holding a copy of our ordinary particle spectrum could lead to oscillations between the neutron (n) and its mirror partner (n′). Such oscillations could manifest themselves in storage experiments with ultracold neutrons whose storage lifetime would depend on the applied magnetic field. Here, extended details and measurements from the first dedicated experimental search for nn′ oscillations published in [G. Ban, K. Bodek, M. Daum, R. Henneck, S. Heule, M. Kasprzak, N. Khomutov, K. Kirch, S. Kistryn, A. Knecht, P. Knowles, M. Kuźniak, T. Lefort, A. Mtchedlishvili, O. Naviliat-Cuncic, C. Plonka, G. Quéméner, M. Rebetez, D. Rebreyend, S. Roccia, G. Rogel, M. Tur, A. Weis, J. Zejma, G. Zsigmond, Direct experimental limit on neutron mirror–neutron oscillations, Phys. Rev. Lett. 99 (2007) 161603] will be presented, focussing on a possible dependence of the UCN counts on the magnetic field and its direction. However, at present no significant change in the averaged UCN counts with respect to the applied magnetic field has been found

Towards a new measurement of the neutron electric dipole moment

The effort towards a new measurement of the neutron electric dipole moment (nEDM) at the Paul Scherrer Institute’s (PSI) new high intensity source of ultracold neutrons (UCN) is described. The experimental technique relies on Ramsey’s method of separated oscillatory fields, using UCN in vacuum with the apparatus at ambient temperature. In the first phase, R&D towards the upgrade of the RAL/ Sussex/ILL apparatus is being performed at the Institut Laue-Langevin (ILL). In the second phase the apparatus, moved from ILL to PSI, will allow an improvement in experimental sensitivity by a factor of 5. In the third phase, a new spectrometer should gain an other order of magnitude in sensitivity. The improvements will be mainly due to (1) much higher UCN intensity, (2) improved magnetometry and magnetic field control, and (3) a double chamber configuration with opposite electric field directions.status: publishe

Towards a new measurement of the neutron electric dipole moment

The effort towards a new measurement of the neutron electric dipole moment (nEDM) at the Paul Scherrer Institut's (PSI) new high intensity source of ultracold neutrons (UCN) is described. The experimental technique relies on Ramsey's method of separated oscillatory fields, using UCN in vacuum with the apparatus at ambient temperature. In the first phase, R&D towards the upgrade of the RAL/Sussex/ILL apparatus is being performed at the Institut Laue-Langevin (ILL). In the second phase the apparatus, moved from ILL to PSI, will allow an improvement in experimental sensitivity by a factor of 5. In the third phase, a new spectrometer should gain another order of magnitude in sensitivity. The improvements will be mainly due to (1) much higher UCN intensity, (2) improved magnetometry and magnetic field control, and (3) a double chamber configuration with opposite electric field directions