daniel brandt [email protected] scientific computing workshop kipac, slac, 20 june 2011...
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Daniel [email protected]
Scientific Computing WorkshopKIPAC, SLAC, 20 June 2011
Simulating CDMS Detector PhysicsA condensed matter energy transport framework for
Geant4
D. Brandt, M. Asai, E. Do Couto e Silva, B. Cabrera
Daniel [email protected]
Scientific Computing WorkshopKIPAC, SLAC, 20 June 2011
The Cryogenic Dark Matter Search•The Cryogenic Dark Matter Search (CDMS) is looking the direct interaction of dark matter with conventional matter
•The sensitive detector mass comprises a set of large high purity Germanium crystals
•Dark matter particles are expected to create free charge carriers and lattice vibrations
Daniel [email protected]
Scientific Computing WorkshopKIPAC, SLAC, 20 June 2011
Phonons in the CDMS detector
Phonon propagation is complicated by two facts:
1. Phonons spontaneously downconvert to low energy pairs with radically longer mean free paths
2. Phonon propagation is highly anisotropic due to anisotropic speed of sound in the crystal
Above: Phonon propagation in Ge, simulated using Geant4
Daniel [email protected]
Scientific Computing WorkshopKIPAC, SLAC, 20 June 2011
Charge propagation in the CDMS detector
Charge propagation is complicated by the Germanium band structure. Electrons behave as though they have an anisotropic mass.
Charge propagation in Geant4 in perspective (left) and from the side (right). Green = electrons, red = holes
Daniel [email protected]
Scientific Computing WorkshopKIPAC, SLAC, 20 June 2011
Full physical model of energy transport
•The full model of energy transport in the detector is implemented using Geant4
•Consequently, the implementation is flexible and highly re-usable
•Fast progress was made possible by the combination of CDMS experts and the core Geant4 development team on site at SLAC
Above: Signal propagation in Ge. Red=hole, green = electron, blue = phonon
Validating the transport codes
The intensity pattern recorded by the detector of a phonon point source at the crystal center is in good agreement with experimental results reported in the literature.
A MatLab version of the simulation yields good agreement of carrier transport properties with experiment. We hope to begin validation of carrier transport in Geant4 in the next few weeks.Image from Cabrera et al., 2010, arxiv 1004.1233v1 Daniel Brandt
[email protected] Computing WorkshopKIPAC, SLAC, 20 June 2011
•The entire project is implemented using the Geant4 toolkit
Daniel [email protected]
Scientific Computing WorkshopKIPAC, SLAC, 20 June 2011
Project implementation & applications
•Our efforts constitute the first condensed matter framework for Geant4•The Geant4 toolkit is freely available under a public license, making our efforts available to the scientific community
•We hope our work will find application in the cryogenic calorimeter community, other rare event search experiments and possibly nano-scale device physics
•This project has been made possible by the unique synergy of having the physics expertise and the Geant4 core development team on the same campus
California Institute of TechnologyZ. Ahmed, J. Filippini, S.R. Golwala, D. Moore
Fermi National Accelerator LaboratoryD. A. Bauer, F. DeJongh, J. Hall, D. Holmgren, L. Hsu, E. Ramberg, R.L. Schmitt, J. Yoo
Massachusetts Institute of TechnologyE. Figueroa-Feliciano, S. Hertel, S.W. Leman, K.A. McCarthy, P. Wikus
NIST K. Irwin
Queen’s UniversityC. Crewdon*, P. Di Stefano *, J. Fox *, S. Liu *, C. Martinez*, P. Nadeau *, W. Rau
Saint Olaf CollegeA. Reisetter
Santa Clara UniversityB. A. Young
SLAC National Accelerator Laboratory/KIPAC *M. Asai, A. Borgland, P. Brink, D. Brandt, W. Craddock, E. do Couto e Silva, .G. Godfrey, J. Hasi, M. Kelsey, C. J. Kenney, P. C. Kim, R. Partridge, R. Resch, A. Tomada, D. Wright
Southern Methodist UniversityJ. Cooley, B. Karabuga, H. Qiu
Stanford UniversityB. Cabrera, M. Cherry, L. Novak, R.W. Ogburn, M. Pyle, M. Razeti *, B. Shank*, S. Yellin, J. Yen*
Syracuse UniversityM. Kos, M. Kiveni, R. W. Schnee
Texas A&MK. Koch*, R. Mahapatra, M. Platt *, K. Prasad *, J. Sander
University of California, BerkeleyM. Daal,T. Doughty, N. Mirabolfathi, A. Phipps, B. Sadoulet, D. Seitz, B. Serfass, D. Speller, K.M. Sundqvist
University of California, Santa BarbaraR. Bunker, D.O. Caldwell, H. Nelson
University of Colorado DenverB.A. Hines, M.E. Huber
University of FloridaT. Saab, D. Balakishiyeva, B. Welliver *
University of Minnesota H. Chagani*, J. Beaty, P. Cushman, S. Fallows, M. Fritts, T Hoffer*, O. Kamaev, V. Mandic, X. Qiu, R. Radpour*,
A. Villano*, J. Zhang* new collaborators or new institutions in SuperCDMS
NSF DOE
about 100 collaborators