Cryogenic Dark Matter Search

Last updated

The Cryogenic Dark Matter Search (CDMS) is a series of experiments designed to directly detect particle dark matter in the form of Weakly Interacting Massive Particles (or WIMPs). Using an array of semiconductor detectors at millikelvin temperatures, CDMS has at times set the most sensitive limits on the interactions of WIMP dark matter with terrestrial materials (as of 2018, CDMS limits are not the most sensitive). The first experiment, CDMS I, was run in a tunnel under the Stanford University campus. It was followed by CDMS II experiment in the Soudan Mine. The most recent experiment, SuperCDMS (or SuperCDMS Soudan), was located deep underground in the Soudan Mine in northern Minnesota and collected data from 2011 through 2015. The series of experiments continues with SuperCDMS SNOLAB, an experiment located at the SNOLAB facility near Sudbury, Ontario in Canada that started construction in 2018 and is expected to start data taking in early 2020s.

Contents

Background

Observations of the large-scale structure of the universe show that matter is aggregated into very large structures that have not had time to form under the force of their own self-gravitation. It is generally believed that some form of missing mass is responsible for increasing the gravitational force at these scales, although this mass has not been directly observed. This is a problem; normal matter in space will heat up until it gives off light, so if this missing mass exists, it is generally assumed to be in a form that is not commonly observed on earth.

A number of proposed candidates for the missing mass have been put forward over time. Early candidates included heavy baryons that would have had to be created in the Big Bang, but more recent work on nucleosynthesis seems to have ruled most of these out. [1] Another candidate are new types of particles known as weakly interacting massive particles, or "WIMP"s. As the name implies, WIMPs interact weakly with normal matter, which explains why they are not easily visible. [1]

Detecting WIMPs thus presents a problem; if the WIMPs are very weakly interacting, detecting them will be extremely difficult. Detectors like CDMS and similar experiments measure huge numbers of interactions within their detector volume in order to find the extremely rare WIMP events.

Detection technology

The CDMS detectors measure the ionization and phonons produced by every particle interaction in their germanium and silicon crystal substrates. [1] These two measurements determine the energy deposited in the crystal in each interaction, but also give information about what kind of particle caused the event. The ratio of ionization signal to phonon signal differs for particle interactions with atomic electrons ("electron recoils") and atomic nuclei ("nuclear recoils"). The vast majority of background particle interactions are electron recoils, while WIMPs (and neutrons) are expected to produce nuclear recoils. This allows WIMP-scattering events to be identified even though they are rare compared to the vast majority of unwanted background interactions.

From supersymmetry, the probability of a spin-independent interaction between a WIMP and a nucleus would be related to the number of nucleons in the nucleus. Thus, a WIMP would be more likely to interact with a germanium detector than a silicon detector, since germanium is a much heavier element. Neutrons would be able to interact with both silicon and germanium detectors with similar probability. By comparing rates of interactions between silicon and germanium detectors, CDMS is able to determine the probability of interactions being caused by neutrons.

CDMS detectors are disks of germanium or silicon, cooled to millikelvin temperatures by a dilution refrigerator. The extremely low temperatures are needed to limit thermal noise which would otherwise obscure the phonon signals of particle interactions. Phonon detection is accomplished with superconduction transition edge sensors (TESs) read out by SQUID amplifiers, while ionization signals are read out using a FET amplifier. CDMS detectors also provide data on the phonon pulse shape which is crucial in rejecting near-surface background events.

History

Bolometric detection of neutrinos with semiconductors at low temperature was first proposed by Blas Cabrera, Lawrence M. Krauss, and Frank Wilczek, [2] and a similar method was proposed for WIMP detection by Mark Goodman and Edward Witten. [3]

CDMS I collected WIMP search data in a shallow underground site (called SUF, Stanford Underground Facility) at Stanford University 1998–2002. CDMS II operated (with collaboration from the University of Minnesota) in the Soudan Mine from 2003 to 2009 (data taking 2006–2008). [4] The newest experiment, SuperCDMS (or SuperCDMS Soudan), with interleaved electrodes, more mass, and even better background rejection was taking data at Soudan 2011–2015. The series of experiments continue with SuperCDMS SNOLAB, currently (2018) under construction in SNOLAB and to be completed in the early 2020s.

The series of experiments also includes the CDMSlite experiment which used SuperCDMS detectors at Soudan in an operating mode (called CDMSlite-mode) that was meant to be sensitive specifically to low-mass WIMPs. As the CDMS-experiment has multiple different detector technologies in use, in particular, 2 types of detectors based on germanium or silicon, respectively, the experiments derived from some specific configuration of the CDMS-experiment detectors and different data-sets thus collected are sometimes given names like CDMS Ge, CDMS Si, CDMS II Si et cetera.

Results

On December 17, 2009, the collaboration announced the possible detection of two candidate WIMPs, one on August 8, 2007, and the other on October 27, 2007. Due to the low number of events, the team could exclude false positives from background noise such as neutron collisions. It is estimated that such noise would produce two or more events 25% of the time. [5] Polythene absorbers were fitted to reduce any neutron background. [6]

A 2011 analysis with lower energy thresholds, looked for evidence for low-mass WIMPs (M < 9 GeV). Their limits rule out hints claimed by a new germanium experiment called CoGeNT and the long-standing DAMA/NaI, DAMA/LIBRA annual modulation result. [7]

Further analysis of data in Physical Review Letters May 2013, revealed 3 WIMP detections with an expected background of 0.7, with masses expected from WIMPs, including neutralinos. There is a 0.19% chance that these are anomalous background noise, giving the result a 99.8% (3 sigmas) confidence level. Whilst not conclusive evidence for WIMPs this provides strong weight to the theories. [8] This signal was observed by the CDMS II-experiment and it is called the CDMS Si-signal (sometimes the experiment is also called CDMS Si) because it was observed by the silicon detectors.

SuperCDMS search results from October 2012 to June 2013 were published in June 2014, finding 11 events in the signal region for WIMP mass less than 30 GeV, and set an upper limit for spin-independent cross section disfavoring a recent CoGeNT low mass signal. [9]

SuperCDMS SNOLAB

A second generation of SuperCDMS is planned for SNOLAB. [10] [11] This is expanded from SuperCDMS Soudan in every way:

The increase in detector mass is not quite as large, because about 25% of the detectors will be made of silicon, [12] : 7  which only weights 44% as much. [14] : 1  Filling all 31 towers at this ratio would result in about 222 kg

Although the project has suffered repeated delays (earlier plans hoped for construction to begin in 2014 [15] and 2016 [13] : 18–25 ), it remains active, [14] with space allocated in SNOLAB and a scheduled construction start in early 2018. [10] : 9 

The construction of SuperCDMS at SNOLAB started in 2018 with beginning of operations in early 2020s. The project budget at the time was US$34 million. [16]

In May 2021, the SuperCDMS SNOLAB detector was under construction, with early science (or prototyping, or preliminary studies) ongoing with prototype/testing hardware, both at the SNOLAB location and at other locations. The full detector was expected ready for science data taking at the end of 2023, and the science operations to last 4 years (with two separate runs) 2023-2027, with possible extensions and developments beyond 2027. [17]

In May 2022, SuperCDMS SNOLAB detector installation was in progress, with a plan to start commissioning run in 2023. First science run with full detector payload in early 2024 and first result in early 2025. [18]

In June 2023, SuperCDMS SNOLAB installation was in full swing. Commissioning was expected to start in 2024. [19]

GEODM proposal

A third generation of SuperCDMS is envisioned, [10] although still in the early planning phase. GEODM (GErmanium Observatory for Dark Matter), with roughly 1500 kg of detector mass, has expressed interest in the SNOLAB "Cryopit" location. [20]

Increasing the detector mass only makes the detector more sensitive if the unwanted background detections do not increase as well, thus each generation must be cleaner and better shielded than the one before. The purpose of building in ten-fold stages like this is to develop the necessary shielding techniques before finalizing the GEODM design.

Related Research Articles

Weakly interacting massive particles (WIMPs) are hypothetical particles that are one of the proposed candidates for dark matter.

The XENON dark matter research project, operated at the Italian Gran Sasso National Laboratory, is a deep underground detector facility featuring increasingly ambitious experiments aiming to detect hypothetical dark matter particles. The experiments aim to detect particles in the form of weakly interacting massive particles (WIMPs) by looking for rare nuclear recoil interactions in a liquid xenon target chamber. The current detector consists of a dual phase time projection chamber (TPC).

<span class="mw-page-title-main">SNOLAB</span> Canadian neutrino laboratory

SNOLAB is a Canadian underground science laboratory specializing in neutrino and dark matter physics. Located 2 km below the surface in Vale's Creighton nickel mine near Sudbury, Ontario, SNOLAB is an expansion of the existing facilities constructed for the original Sudbury Neutrino Observatory (SNO) solar neutrino experiment.

The ArDM Experiment was a particle physics experiment based on a liquid argon detector, aiming at measuring signals from WIMPs, which may constitute the Dark Matter in the universe. Elastic scattering of WIMPs from argon nuclei is measurable by observing free electrons from ionization and photons from scintillation, which are produced by the recoiling nucleus interacting with neighbouring atoms. The ionization and scintillation signals can be measured with dedicated readout techniques, which constituted a fundamental part of the detector.

<span class="mw-page-title-main">DEAP</span> Dark matter search experiment

DEAP is a direct dark matter search experiment which uses liquid argon as a target material. DEAP utilizes background discrimination based on the characteristic scintillation pulse-shape of argon. A first-generation detector (DEAP-1) with a 7 kg target mass was operated at Queen's University to test the performance of pulse-shape discrimination at low recoil energies in liquid argon. DEAP-1 was then moved to SNOLAB, 2 km below Earth's surface, in October 2007 and collected data into 2011.

<span class="mw-page-title-main">Large Underground Xenon experiment</span>

The Large Underground Xenon experiment (LUX) aimed to directly detect weakly interacting massive particle (WIMP) dark matter interactions with ordinary matter on Earth. Despite the wealth of (gravitational) evidence supporting the existence of non-baryonic dark matter in the Universe, dark matter particles in our galaxy have never been directly detected in an experiment. LUX utilized a 370 kg liquid xenon detection mass in a time-projection chamber (TPC) to identify individual particle interactions, searching for faint dark matter interactions with unprecedented sensitivity.

<span class="mw-page-title-main">Cryogenic Rare Event Search with Superconducting Thermometers</span>

The Cryogenic Rare Event Search with Superconducting Thermometers (CRESST) is a collaboration of European experimental particle physics groups involved in the construction of cryogenic detectors for direct dark matter searches. The participating institutes are the Max Planck Institute for Physics (Munich), Technical University of Munich, University of Tübingen (Germany), University of Oxford, the Comenius University Bratislava (Slovakia) and the Istituto Nazionale di Fisica Nucleare.

Light dark matter, in astronomy and cosmology, are dark matter weakly interacting massive particles (WIMPS) candidates with masses less than 1 GeV. These particles are heavier than warm dark matter and hot dark matter, but are lighter than the traditional forms of cold dark matter, such as Massive Compact Halo Objects (MACHOs). The Lee-Weinberg bound limits the mass of the favored dark matter candidate, WIMPs, that interact via the weak interaction to GeV. This bound arises as follows. The lower the mass of WIMPs is, the lower the annihilation cross section, which is of the order , where m is the WIMP mass and M the mass of the Z-boson. This means that low mass WIMPs, which would be abundantly produced in the early universe, freeze out much earlier and thus at a higher temperature, than higher mass WIMPs. This leads to a higher relic WIMP density. If the mass is lower than GeV the WIMP relic density would overclose the universe.

The DAMA/LIBRA experiment is a particle detector experiment designed to detect dark matter using the direct detection approach, by using a matrix of NaI(Tl) scintillation detectors to detect dark matter particles in the galactic halo. The experiment aims to find an annual modulation of the number of detection events, caused by the variation of the velocity of the detector relative to the dark matter halo as the Earth orbits the Sun. It is located underground at the Laboratori Nazionali del Gran Sasso in Italy.

<span class="mw-page-title-main">European Underground Rare Event Calorimeter Array</span> Planned dark matter search experiment

The European Underground Rare Event Calorimeter Array (EURECA) is a planned dark matter search experiment using cryogenic detectors and an absorber mass of up to 1 tonne. The project will be built in the Modane Underground Laboratory and will bring together researchers working on the CRESST and EDELWEISS experiments.

<span class="mw-page-title-main">EDELWEISS</span>

EDELWEISS is a dark matter search experiment located at the Modane Underground Laboratory in France. The experiment uses cryogenic detectors, measuring both the phonon and ionization signals produced by particle interactions in germanium crystals. This technique allows nuclear recoils events to be distinguished from electron recoil events.

SIMPLE is an experiment search for direct evidence of dark matter. It is located in a 61 m3 cavern at the 500 level of the Laboratoire Souterrain à Bas Bruit near Apt in southern France. The experiment is predominantly sensitive to spin-dependent interactions of weakly interacting massive particles.

The Korea Invisible Mass Search (KIMS), is a South Korean experiment, led by Sun Kee Kim, searching for weakly interacting massive particles (WIMPs), one of the candidates for dark matter. The experiments use CsI(Tl) crystals at Yangyang Underground Laboratory (Y2L), in tunnels from a preexisting underground power plant. KIMS is supported by the Creative Research Initiative program of the Korea Science and Engineering Foundation. It is the first physics experiment located, and largely built, in Korea.

The Particle and Astrophysical Xenon Detector, or PandaX, is a dark matter detection experiment at China Jinping Underground Laboratory (CJPL) in Sichuan, China. The experiment occupies the deepest underground laboratory in the world, and is among the largest of its kind.

<span class="mw-page-title-main">LZ experiment</span> Experiment in South Dakota, United States

The LUX-ZEPLIN (LZ) Experiment is a next-generation dark matter direct detection experiment hoping to observe weakly interacting massive particles (WIMP) scatters on nuclei. It was formed in 2012 by combining the LUX and ZEPLIN groups. It is currently a collaboration of 30 institutes in the US, UK, Portugal and South Korea. The experiment is located at the Sanford Underground Research Facility (SURF) in South Dakota, and is managed by the United States Department of Energy's (DOE) Lawrence Berkeley National Lab.

The CoGeNT experiment has searched for dark matter. It uses a single germanium crystal as a cryogenic detector for WIMP particles. CoGeNT has operated in the Soudan Underground Laboratory since 2009.

<span class="mw-page-title-main">Jocelyn Monroe</span> American experimental particle physicist

Jocelyn Monroe is an American British experimental particle physicist who is a professor at the University of Oxford. Her research considers the development of novel detectors as part of the search for dark matter. In 2016 she was honoured with the Breakthrough Prize in Fundamental Physics for her work on the Sudbury Neutrino Observatory.

<span class="mw-page-title-main">ANAIS-112</span> Spanish dark matter direct detection experiment

ANAIS is a dark matter direct detection experiment located at the Canfranc Underground Laboratory (LSC), in Spain.

Direct detection of dark matter is the science of attempting to directly measure dark matter collisions in Earth-based experiments. Modern astrophysical measurements, such as from the Cosmic Microwave Background, strongly indicate that 85% of the matter content of the universe is unaccounted for. Although the existence of dark matter is widely believed, what form it takes or its precise properties has never been determined. There are three main avenues of research to detect dark matter: attempts to make dark matter in accelerators, indirect detection of dark matter annihilation, and direct detection of dark matter in terrestrial labs. The founding principle of direct dark matter detection is that since dark matter is known to exist in the local universe, as the Earth, Solar System, and the Milky Way Galaxy carve out a path through the universe they must intercept dark matter, regardless of what form it takes.

Daniel S. Akerib is an American particle physicist and astrophysicist. He was elected in 2008 a fellow of the American Physical Society (APS).

References

  1. 1 2 3 "WIMP Dark Matter" Archived 2002-06-01 at the Wayback Machine , CDMSII Overview, University of California, Berkeley
  2. ↑ B. Cabrera; L.M. Krauss; F. Wilczek (July 1985), "Bolometric detection of neutrinos", Phys. Rev. Lett., 55 (1): 25–28, Bibcode:1985PhRvL..55...25C, doi:10.1103/PhysRevLett.55.25, PMID   10031671
  3. ↑ M.W. Goodman; E. Witten (15 June 1985), "Detectability of certain dark matter candidates", Phys. Rev. D, 31 (12): 3059–3063, Bibcode:1985PhRvD..31.3059G, doi:10.1103/PhysRevD.31.3059, PMID   9955633
  4. ↑ Ananthaswamy, Anil (2010-03-02). The Edge of Physics: A Journey to Earth's Extremes to Unlock the Secrets of the Universe. HMH. ISBN   978-0-547-48846-2.
  5. ↑ "Latest Results in the Search for Dark Matter Thursday, December 17, 2009" Archived June 18, 2010, at the Wayback Machine
  6. ↑ "CDMS cryostat without detectors". Archived from the original on 2000-08-18. Retrieved 2011-09-23.
  7. ↑ CDMS Collaboration (21 Apr 2011). "Results from a Low-Energy Analysis of the CDMS II Germanium Data". Physical Review Letters. 106 (13): 131302. arXiv: 1011.2482 . Bibcode:2011PhRvL.106m1302A. doi:10.1103/PhysRevLett.106.131302. PMID   21517371. S2CID   9879642.
  8. ↑ CDMS Collaboration (4 May 2013). "Dark Matter Search Results Using the Silicon Detectors of CDMS II". Physical Review Letters. 111 (25): 251301. arXiv: 1304.4279 . Bibcode:2013PhRvL.111y1301A. doi:10.1103/PhysRevLett.111.251301. PMID   24483735. S2CID   3073653.
  9. ↑ Agnese, R.; Anderson, A. J.; Asai, M.; Balakishiyeva, D.; Basu Thakur, R.; Bauer, D. A.; Beaty, J.; Billard, J.; Borgland, A.; Bowles, M. A.; Brandt, D.; Brink, P. L.; Bunker, R.; Cabrera, B.; Caldwell, D. O.; Cerdeno, D. G.; Chagani, H.; Chen, Y.; Cherry, M.; Cooley, J.; Cornell, B.; Crewdson, C. H.; Cushman, P.; Daal, M.; Devaney, D.; Di Stefano, P. C. F.; Silva, E. Do Couto E.; Doughty, T.; Esteban, L.; et al. (June 20, 2014). "Search for Low-Mass WIMPs with SuperCDMS". Phys. Rev. Lett. 112 (24): 241302. arXiv: 1402.7137 . Bibcode:2014PhRvL.112x1302A. doi:10.1103/PhysRevLett.112.241302. hdl:1721.1/88645. PMID   24996080. S2CID   119066853.
  10. 1 2 3 4 Cushman, Priscilla (2012-07-22), "The Cryogenic Dark Matter Search: Status and Future Plans" (PDF), IDM Conference
  11. 1 2 Saab, Tarek (2012-08-01), "The SuperCDMS Dark Matter Search" (PDF), SLAC Summer Institute 2012, SLAC National Accelerator Laboratory, archived from the original (PDF) on 2015-09-24, retrieved 2012-11-28 (presentation)
  12. 1 2 Rau, Wolfgang (25 July 2017). SuperCDMS SNOLAB—Status and Plans. XV International Conference on Topics in Astroparticle and Underground Physics (TAUP 2017). Sudbury, Canada.
  13. 1 2 Brink, Paul (25 June 2015). SuperCDMS results and plans for SNOLAB. 11th Patras Workshop on Axions, WIMPs and WISPs. Zaragoza, Spain.
  14. 1 2 Agnese, R.; et al. (SuperCDMS Collaboration) (2017-04-07). "Projected sensitivity of the SuperCDMS SNOLAB experiment" (PDF). Physical Review D . 95 (8): 082002. arXiv: 1610.00006 . Bibcode:2017PhRvD..95h2002A. doi:10.1103/PhysRevD.95.082002. hdl:1721.1/109800. S2CID   32272925. Archived from the original (PDF) on 2017-10-22. Retrieved 2017-10-22.
  15. ↑ "Second generation dark matter experiment coming to SNOLAB" (Press release). SNOLAB. 2014-07-18. Archived from the original on 2019-03-30. Retrieved 2014-09-18.
  16. ↑ "Construction Begins on SuperCDMS Dark Matter Experiment".
  17. ↑ "CERN" (PDF).
  18. ↑ "Sanford Lab" (PDF).
  19. ↑ "Indico" (PDF).
  20. ↑ Golwala, Sunil (2011-08-15). GEODM Interest in the SNOLAB Cryopit (PDF). Archived from the original (PDF) on 2016-03-04. Retrieved 2015-12-07.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.