Comparing the Calibration and Simulation Data of the Cryogenic Dark Matter Search

DiFranzo, Anthony ; /Rensselaer Poly. /SLAC

关键词: CALIBRATION;    CHARGE TRANSPORT;    CRYOGENICS;    CRYSTAL LATTICES;    DECAY;    DETECTION;    GE SEMICONDUCTOR DETECTORS;    GERMANIUM;    IONIZATION;    NONLUMINOUS MATTER;    PHONONS;    PRODUCTION;    PULSE RISE TIME;    RADIATIONS;    SCATTERING;    SIMULATION Astrophysics;    Other;   

DOI  :  10.2172/1017225
RP-ID  :  SLAC-TN-11-004
PID  :  OSTI ID: 1017225
Others  :  TRN: US1103335

学科分类：物理（综合）

美国|英语

来源: SciTech Connect

【 摘 要 】

The Cryogenic Dark Matter Search, or CDMS, collaboration is preparing a new experiment called SuperCDMS. CDMS uses Germanium detectors to attempt the direct detection of dark matter. To do this, they measure the ionization and heat produced during an event where a WIMP scatters off of germanium crystal lattice. To prepare for the experiment the detectors are calibrated with various radioactive sources. The response of the detectors is also modeled by a Monte Carlo simulation. These simulations include modeling everything from the radiation production to the raw data collected by the detector. The experimental data will be used to validate the results of the detector simulation. This research will look only at the phonons produced during events that occur very close to the detector surface. From the raw data and simulation output three parameters will be determined: the rise time, the decay time, and time to position independence. It was found that the simulation's risetime and time to position independence was generally smaller than that of the data, while the decay time was found to be larger in the simulation than in the data. These differences show that the simulation is not complete. The difference in risetime implies that the phonons are not spread out enough when they reach the detector walls, which would be improved by a look at the Luke phonon and charge transport. The long decay time in the simulation implies that the rate phonons are being absorbed is underestimated. Finally, the small time to position independence in the simulation could be due to a low phonon scattering rate. A simple solution may be to alter the parameters that control the simulation, while still remaining physically sensible, to help match simulation and data.