- Main
α-event characterization and rejection in point-contact HPGe detectors
- Arnquist, IJ;
- Avignone, FT;
- Barabash, AS;
- Barton, CJ;
- Bertrand, FE;
- Blalock, E;
- Bos, B;
- Busch, M;
- Buuck, M;
- Caldwell, TS;
- Chan, Y-D;
- Christofferson, CD;
- Chu, P-H;
- Clark, ML;
- Cuesta, C;
- Detwiler, JA;
- Drobizhev, A;
- Edwards, TR;
- Edwins, DW;
- Edzards, F;
- Efremenko, Y;
- Elliott, SR;
- Gilliss, T;
- Giovanetti, GK;
- Green, MP;
- Gruszko, J;
- Guinn, IS;
- Guiseppe, VE;
- Haufe, CR;
- Hegedus, RJ;
- Henning, R;
- Aguilar, D Hervas;
- Hoppe, EW;
- Hostiuc, A;
- Kim, I;
- Kouzes, RT;
- Lopez, AM;
- López-Castaño, JM;
- Martin, EL;
- Martin, RD;
- Massarczyk, R;
- Meijer, SJ;
- Mertens, S;
- Myslik, J;
- Oli, TK;
- Othman, G;
- Pettus, W;
- Poon, AWP;
- Radford, DC;
- Rager, J;
- Reine, AL;
- Rielage, K;
- Ruof, NW;
- Saykı, B;
- Schönert, S;
- Stortini, MJ;
- Tedeschi, D;
- Varner, RL;
- Vasilyev, S;
- Wilkerson, JF;
- Willers, M;
- Wiseman, C;
- Xu, W;
- Yu, C-H;
- Zhu, BX
- et al.
Published Web Location
https://doi.org/10.1140/epjc/s10052-022-10161-yAbstract
P-type point contact (PPC) HPGe detectors are a leading technology for rare event searches due to their excellent energy resolution, low thresholds, and multi-site event rejection capabilities. We have characterized a PPC detector's response to α particles incident on the sensitive passivated and p + surfaces, a previously poorly-understood source of background. The detector studied is identical to those in the Majorana Demonstrator experiment, a search for neutrinoless double-beta decay ( 0 ν β β ) in 76 Ge. α decays on most of the passivated surface exhibit significant energy loss due to charge trapping, with waveforms exhibiting a delayed charge recovery (DCR) signature caused by the slow collection of a fraction of the trapped charge. The DCR is found to be complementary to existing methods of α identification, reliably identifying α background events on the passivated surface of the detector. We demonstrate effective rejection of all surface α events (to within statistical uncertainty) with a loss of only 0.2% of bulk events by combining the DCR discriminator with previously-used methods. The DCR discriminator has been used to reduce the background rate in the 0 ν β β region of interest window by an order of magnitude in the Majorana Demonstrator and will be used in the upcoming LEGEND-200 experiment.
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