New search for the neutron electric dipole moment with ultracold neutrons at ILL

Comparison of ultracold neutron sources for fundamental physics measurements

“…This was for a long time the only source with sufficient UCNs available. At the beginning experiments concentrated on measurements of the free neutron lifetime (τ n ) [5][6][7][8] and on the search for a permanent electric dipole moment of the neutron (nEDM) [9][10][11][12][13]. In addition to the fundamental particle aspect, τ n is also an important quantity in understanding the primordial nucleo-synthesis and contributes presently one of the larger uncertainties to its description [14].…”

The pulsed neutron beam EDM experiment

“…The search for a finite neutron EDM remains a top priority. It has become a worldwide endeavor which is followed by various research teams setting up experiments for improved measurements [2][3][4][5][6][7][8][9][10]. All these collaborations are using or are planning to use ultracold neutrons, since they have the advantage of long interaction times.…”

An ultracold neutron storage bottle for UCN density measurements

“…Such neutrons are reflected under all angles of incidence from surfaces of suitable materials. Therefore, UCN can be confined in material containers, dubbed 'storage bottles', in which storage times of several hundreds of seconds are possible and ultimately limited by the neutron beta-decay lifetime of 880 s. This unique feature makes UCN ideal to study fundamental properties of the neutron in precision experi-ments [1] like most prominently in the search for an electric dipole moment of the neutron (nEDM) [2][3][4][5][6] or the determination of the lifetime of the free neutron [7,8], the measurement of neutron decay correlations [9][10][11] or the investigation of neutron states bound in the Earth's gravitational field [12][13][14].…”