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Title: Development of a Navigator and Imaging Techniques for the Cryogenic Dark Matter Search Detectors

Abstract

This project contributes to the detection of flaws in the germanium detectors for the Cryogenic Dark Matter Search (CDMS) experiment. Specifically, after imaging the detector surface with a precise imaging and measuring device, they developed software to stitch the resulting images together, applying any necessary rotations, offsets, and averaging, to produce a smooth image of the whole detector that can be used to detect flaws on the surface of the detector. These images were also tiled appropriately for the Google Maps API to use as a navigation tool, allowing viewers to smoothly zoom and pan across the detector surface. Automated defect identification can now be implemented, increasing the scalability of the germanium detector fabrication.

Authors:
;
Publication Date:
Research Org.:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1017209
Report Number(s):
SLAC-TN-11-018
TRN: US201113%%685
DOE Contract Number:
AC02-76SF00515
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; CRYOGENICS; DEFECTS; DETECTION; FABRICATION; GE SEMICONDUCTOR DETECTORS; NAVIGATION; NONLUMINOUS MATTER; Astrophysics, Instrumentation,Other

Citation Formats

Wilen, Chris, and /Carleton Coll. /KIPAC, Menlo Park. Development of a Navigator and Imaging Techniques for the Cryogenic Dark Matter Search Detectors. United States: N. p., 2011. Web. doi:10.2172/1017209.
Wilen, Chris, & /Carleton Coll. /KIPAC, Menlo Park. Development of a Navigator and Imaging Techniques for the Cryogenic Dark Matter Search Detectors. United States. doi:10.2172/1017209.
Wilen, Chris, and /Carleton Coll. /KIPAC, Menlo Park. 2011. "Development of a Navigator and Imaging Techniques for the Cryogenic Dark Matter Search Detectors". United States. doi:10.2172/1017209. https://www.osti.gov/servlets/purl/1017209.
@article{osti_1017209,
title = {Development of a Navigator and Imaging Techniques for the Cryogenic Dark Matter Search Detectors},
author = {Wilen, Chris and /Carleton Coll. /KIPAC, Menlo Park},
abstractNote = {This project contributes to the detection of flaws in the germanium detectors for the Cryogenic Dark Matter Search (CDMS) experiment. Specifically, after imaging the detector surface with a precise imaging and measuring device, they developed software to stitch the resulting images together, applying any necessary rotations, offsets, and averaging, to produce a smooth image of the whole detector that can be used to detect flaws on the surface of the detector. These images were also tiled appropriately for the Google Maps API to use as a navigation tool, allowing viewers to smoothly zoom and pan across the detector surface. Automated defect identification can now be implemented, increasing the scalability of the germanium detector fabrication.},
doi = {10.2172/1017209},
journal = {},
number = ,
volume = ,
place = {United States},
year = 2011,
month = 6
}

Technical Report:

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  • Dark Matter Search - During the period of performance, our group continued the search for dark matter in the form of weakly interacting massive particles or WIMPs. As a key member of the CDMS (Cryogenic Dark Matter Search) collaboration, we completed the CDMS II experiment which led the field in sensitivity for more than five years. We fabricated all detectors, and participated in detector testing and verification. In addition, we participated in the construction and operation of the facility at the Soudan Underground Laboratory and played key roles in the data acquisition and analysis. Towards the end of the performancemore » period, we began operating the SuperCDMS Soudan experiment, which consists of 15 advanced Ge (9 kg) detectors. The advanced detector design called iZIP grew out of our earlier DOE Particle Detector R&D program which demonstrated the rejection of surface electrons to levels where they are no longer the dominant source of background. Our group invented this advanced design and these larger detectors were fabricated on the Stanford campus in collaboration with the SLAC CDMS group and the Santa Clara University group. The sensitivity reach is expected to be up to 5 times better than CDMS II after two years of operation. We will check the new limits on WIMPs set by XENON100, and we expect improved sensitivity for light mass WIMPs beyond that of any other existing experiment. Our group includes the Spokesperson for SuperCDMS and continues to make important contributions to improvements in the detector technology which are enabling the very low trigger thresholds used to explore the low mass WIMP region. We are making detailed measurements of the charge transport and trapping within Ge crystals, measuring the diffusive trapping distance of the quasiparticle excitations within the Al phonon collector fins on the detector surface, and we are contributing to the development of much improved detector Monte Carlos which are essential to guide the detector design and optimize the analysis. Neutrino Physics – In the period of performance the neutrino group successfully completed the construction of EXO-200 and commissioned the detector. Science data taking started on Jun 1, 2011. With the discovery of the 2-neutrino double-beta decay in 136-Xe and the first measurement of the 0-neutrino mode resulting in the most stringent limit of Majorana masses, our group continues to be a leading innovator in the field of neutrino physics which is central to DOE-HEP Intensity Frontier program. The phenomenon of neutrino oscillations, in part elucidated by our earlier efforts with the Palo Verde and KamLAND experiments, provides the crucial information that neutrino masses are non-zero and, yet, it contains no information on the value of the neutrino mass scale. In recent times our group has therefore shifted its focus to a high sensitivity 0-neutrino double beta decay program, EXO. The 0-neutrino double beta decay provides the best chance of extending the sensitivity to the neutrino mass scale below 10 meV but, maybe more importantly, it tests the nature of the neutrino wave function, providing the most sensitive probe for Majorana particles and lepton number violation. The EXO program, formulated by our group several years ago, plans to use up to tonnes of the isotope 136-Xe to study the 0-neutrino double beta decay mode. The EXO-200 detector is the first step in this program and it represents the only large US-led and based experiment taking data. The EXO-200 isotope enrichment program broke new grounds for the enterprise of double beta decay. The detector design and material selection program paid off, resulting in a background that is among the very best in the field. The “first light" of EXO-200 was very exciting with the discovery -in the first month of data- of the rarest 2-neutrino double beta decay mode ever observed. The lower limit on the 0-neutrino double beta decay half-life, published in Phys. Rev. Lett. and based on the first 120 days of data is the second best but, when translated into a Majorana mass scale, it is one of the most stringent constraint we have on neutrino masses. Indeed, such a limit was the first result to contradict a claim of discovery in 76-Ge for most nuclear matrix elements calculations. As we continue data taking and plan some modest upgrades to EXO-200 our group is also very active in the design of nEXO, a 5 tonne detector based on the technology demonstrated by EXO-200. Over the years we have made it a tradition to explore the frontier and not to be shy about looking in new directions and re-inventing ourselves to best take advantage of the precious few opportunities provided by Nature. We have also cultivated a number of young people at all levels and, by now, many of the undergraduates, graduate students and postdocs educated by this group have leading positions in academia and industry around the world.« less
  • A wide variety of astrophysical observations indicate that approximately 85% of the matter in the universe is nonbaryonic and nonluminous. Understanding the nature of this "dark matter" is one of the most important outstanding questions in cosmology. Weakly Interacting Massive Particles (WIMPs) are a leading candidate for dark matter since they would be thermally produced in the early universe in the correct abundance to account for the observed relic density of dark matter. If WIMPs account for the dark matter, then rare interactions from relic WIMPs should be observable in terrestrial detectors. Recently, unexplained excess events in the DAMA/LIBRA, CoGeNT,more » and CRESST-II experiments have been interpreted as evidence of scattering from WIMPs with masses ~10 GeV and spin-independent scattering cross sections of 10-41-10-40 cm 2. The Cryogenic Dark Matter Search (CDMS II) attempts to identify WIMP interactions using an array of cryogenic germanium and silicon particle detectors located at the Soudan Underground Laboratory in northern Minnesota. In this dissertation, data taken by CDMS II are reanalyzed using a 2 keV recoil energy threshold to increase the sensitivity to WIMPs with masses ~10 GeV. These data disfavor an explanation for the DAMA/LIBRA, CoGeNT, and CRESST-II results in terms of spin-independent elastic scattering of WIMPs with masses ≲12 GeV, under standard assumptions. At the time of publication, they provided the strongest constraints on spin-independent elastic scattering from 5-9 GeV, ruling out previously unexplored parameter space. To detect WIMPs or exclude the remaining parameter space favored by the most popular models will ultimately require detectors with target masses ≳1 ton, requiring an increase in mass by more than two orders of magnitude over CDMS II. For cryogenic detectors such as CDMS, scaling to such large target masses will require individual detector elements to be fabricated more quickly and cheaply, while maintaining the nearly background-free operation of the existing experiment. We describe the development of athermal phonon mediated particle detectors using Microwave Kinetic Inductance Detectors (MKIDs), which could provide a simpler path to extending the CDMS detector technology to the ton scale. Results from prototype devices have demonstrated energy resolutions as good as σ = 0.55 keV at 30 keV, comparable to existing CDMS II detectors. Such designs can be scaled to kg-scale detector elements, while reducing the complexity of the detector fabrication and cryogenic readout electronics relative to existing designs. Since MKIDs are naturally multiplexed in the frequency domain, MKID-based designs also allow much finer pixelization of the phonon sensor, which is expected to enhance background rejection for large detectors while simultaneously reducing the number of wires needed to read out the detectors.« less
  • We have supported one graduate student and a small percentage of fabrication staff on $135k per year for three years plus one no cost extension year on this DUSEL R&D grant. There were three themes within our research program: (1) how to improve the radial sensitivity for single sided phonon readout with four equal area sensors of which three form a central circle and fourth a surrounding ring; (2) how to instrument double sided phonon readouts which will give us better surface event rejection and increased fiducial volume for future CDMS style detectors; and (3) can we manufacture much largermore » Ge detectors using six inch diameter material which is not suitable for standard gamma ray spectroscopy.« less
  • Our program in non-accelerator high energy physics was aimed at searching for non-baryonic dark matter which may be present in the cosmic-rays with laboratory based experiments. The first search of this type was performed by our group using superconducting induction detectors to look for a particle flux of magnetic monopoles. We operated two generations of monopole detectors under this Contract funding period and we have set important upper particle flux limits. During the second half of the Contract period, we broadened our program to include the search for other forms of non-baryonic dark matter. In particular, we developed new particlemore » detectors sensitive to neutral particles which interact weakly with matter. These detectors are based on phonon propagation in silicon crystals at temperatures below 1 K. Under separate future funding, we will use these detectors in reactor neutrino experiments. These experiments would include verifying the neutrino-nucleus coherent elastic scattering cross-section, performing more sensitive neutrino oscillation experiments and setting better limits on the neutrino magnetic dipole moment.« less
  • Our program in non-accelerator high energy physics was aimed at searching for non-baryonic dark matter which may be present in the cosmic-rays with laboratory based experiments. The first search of this type was performed by our group using superconducting induction detectors to look for a particle flux of magnetic monopoles. We operated two generations of monopole detectors under this Contract funding period and we have set important upper particle flux limits. During the second half of the Contract period, we broadened our program to include the search for other forms of non-baryonic dark matter. In particular, we developed new particlemore » detectors sensitive to neutral particles which interact weakly with matter. These detectors are based on phonon propagation in silicon crystals at temperatures below 1 K. Under separate future funding, we will use these detectors in reactor neutrino experiments. These experiments would include verifying the neutrino-nucleus coherent elastic scattering cross-section, performing more sensitive neutrino oscillation experiments and setting better limits on the neutrino magnetic dipole moment.« less