Development of crystal calorimeters for applications in fundamental and applied sciences
Project Status: 3 Approved without Funding
Duration in months: 36 months
Objective
The project is devoted to the HEPI TSU group participation in the basic and applied research carrying out by the JEDI international collaboration at the Forschungszentrum-Juelich (Juelich, Germany). The main goal of the Collaboration is a search of a permanent electric dipole moment (EDM) of charged hadrons. The EDMs of elementary particles occur when the centroids of positive and negative charges are permanently displaced. An EDM observation could explain the matter-antimatter asymmetry in the Universe and also be a strong indication for physics beyond the Standard Model of particle physics.
EDMs are very small - the best current upper limit for the neutron is 10-26 e•cm - and the goal for charged particles in the ultimate project is 10-29 e•cm or even better. In spite of the simplicity of the measurement principle - following the time development of the polarization vector of particles subject to a perpendicular electric field - the smallness of the effect provides exceptional challenges, e.g., to identify and/or avoid any fake signal. If an electric dipole moment exists, the spin vector, which is oriented parallel to the EDM direction, will experience a torque in an external electric field, resulting in a change in the original spin direction. This minuscule spin rotation (about 1 µrad/s for an EDM of 10-26 e•cm) can be determined with the help of a polarimeter (a detector to determine the spin direction). The measurements with stored deuteron and proton beams at COSY (Coler Synchrotron and storage ring) is the first step towards the dedicated storage ring with two beams circulating in opposite directions.
For these extremely precise beam polarization measurement it is absolutely necessary to build a dedicated polarimeter to control the circulating beam transverse polarization direction. General requirements for the EDM polarimeter are the following. An excellent capability to measure very low (close to zero) beam transverse polarization, to distinguish reliably useful events from accompanying background, to eliminate the systematic errors, and to operate continuously on-line with high efficiency.
The second major direction of the HEPI TSU group activity, which overlaps with the crystal calorimeter development, concerns to the heavy crystal usage in the positron emission tomography (PET) and its integration with magnetic resonance imaging (MR) device. The main problem of MR and PET integration is the radial space limitation for PET and the presence of a strong magnetic field inside the MR coil. So we would like to carry out R&D study in order to overcome these obstacles, to increase the effective sensitive area for PET using the same crystal modules as for the beam calorimeter. Our main goal is to achieve PET module optimization in order to build the module with minimal space occupation, magnetic field resistance, moderate number of channels, and high efficiency.
The EDM search is purely fundamental physics task, requiring a long term activity and a huge resources, whereas the PET calorimeter module development concerns to the applied research and has to be achieved as soon as possible. At the time being these two tasks of our activity are of the common goal, namely heavy crystal calorimeter R&D with almost the same required characteristics and features.
The HEPI TSU group is a member of the JEDI international collaboration at COSY IKP comprising more than 100 collaborators. The HEPI TSU has accepted the responsibility for design, development, and build a modern, state-of-the-art polarimeter with excellent performance. The group has more than 20 years successful experience of collaboration with Nuclear Physics Institute (IKP) of the Forschungszentrum-Juelich (Juelich, Germany).
