Performance of Planacon MCP-PMT photosensors under extreme working conditions

Status of the Fast Interaction Trigger for ALICE Collaboration

“…The design details and results of tests of several FIT detector prototypes have already been published before (see [2][3][4][5][6]), as well as the simulated detector performance (see [7,8]). The focus of this paper is on the final FEE and its response to signals from real detectors.…”

Performance of the cost-effective Planacon ® MCP-PMTs in strong magnetic fields

“…According to our preliminary study done for a single Planacon and reported before [9], placing the device biased to the gain of 1.5•10 4 in a 0.5 T magnetic field results in a decrease in gain by a factor of 2.5. This reasonably small value was only measured for the total bias voltage of 1.35 kV, so this limited study is insufficient to predict the operability…”

“…Testing the device at a lower bias voltage, e.g. 1.15 kV, has shown a decrease in gain by a factor of ~8 [9]. Such a significant gain drop is undesirable for many applications, including for use in the ALICE FIT detector.…”

“…To complete the project, we need 52 (+10 spare) PMTs to be operational at 1.5•10 4 electron gain in the magnetic field of the ALICE L3 solenoid magnet [1] (typically ±0.2 T or ±0.5 T). In the case of FIT, the low-gain operation is optimal to detect relativistic particles with the best timing in a wide range of particle flux values [9], keeping the devices in the linear operation mode. 62 Planacons for ALICE FIT were manufactured throughout 2018 and 2019.…”

The Fast Interaction Trigger Upgrade for ALICE

“…FT0 consists of two arrays of 24 and 28 Cherenkov modules placed asymmetrically on the opposite sides of the interaction point. Each module operates as 4 independent quadrants with separate 2-cm-thick quartz radiator optically coupled to MCP-PMT (PLANACON XP85012/FIT-Q) [5]. The PMTs were customized in order to reduce electronic crosstalk and improve the time resolution.…”