24-28 February 2020
Budker Institute of Nuclear Physics
Asia/Novosibirsk timezone

The GEM-based detector for tracking the Compton-scattered photons in the Laser Polarimeter facility at VEPP4-M collider.

Not scheduled
Budker Institute of Nuclear Physics

Budker Institute of Nuclear Physics

11, akademika Lavrentieva prospect, Novosibirsk, Russia
Board: 36
Poster Micropattern gas detectors


Mr Vasily Kudryavtsev (BINP, NSU)


The VEPP4-M collider has a unique system for energy measurement based on Resonance Depolarization technique. The existing system is working well using the Touschek effect for measurement of polarization at the energies below 2 GeV. For higher energies it is suggested to use the effect of asymmetry of reflected polarized laser photons back-scattered from polarized beam. For the measurement of polarization degree of the beam the coordinates of compton scattered photons are registered with different polarization of the laser. Since non-polarized beam does not produce asymmetry, thus difference in mean coordinate yields the information about polarization degree of the beam. For registering of coordinates of reflected photons the special gaseous detector with triple-GEM was manufactured. The readout structure is a rectangular grid of 1120 pads, which are 2x1 mm sized in center and 4x2 mm on the edge where bigger pads are used for a rough alignment of the detector. In front of sensitive area the lead convertor is placed which converts the reflected photons into charged particles registered by the detector. The trigger for the detector, which is the same signal fed to laser, is generated by frequency division of VEPP4-M bunch crossing signal and is in the range of 1-4 kHz while the laser polarization can be switched on every flash. For the gathering of signals from the pads of the readout structure the DMXG64 front-end ASICs, which were developed at BINP, are used. The prototype detector was tested and the principle was proved. The final detector is assembled and first results will be presented at the conference.


The Laser Polarimeter is being developed at VEPP-4M collider for beam energy
calibration by Resonant Depolarization technique. The essential part of this facility is a photon-tracking detector measuring coordinates of backscattered gammas. The final detector is assembled and first results will be presented at the conference.

Primary author

Mr Vasily Kudryavtsev (BINP, NSU)


Dr Ivan Nikolaev (Budker Insitute of Nuclear Physics) Mr Lev Shekhtman (Budker Institute of Nuclear Physics) Prof. Nikolai Muchnoi (Budker INP SB RAS) Dr Sergey Nikitin (BINP) Viacheslav Kaminskiy (Budker Institute of Nuclear Physics SB RAS) Dr Vladimir Blinov (BINP)

Presentation Materials