The Cryogenic Dark Matter Search (CDMS) attempts to detect dark matter in the form of Weakly Interacting Massive Particles, or WIMPs.\u00a0 The project uses low-temperature devices to detect these particles via scattering from nuclei.\u00a0 Such experiments involve considerable background events, and much effort is devoted to developing ways to discriminate WIMP scatters from other sources of particles.\u00a0 Most subatomic particles that reach the detectors are electrically charged, and thus interact with the electrons of the detectors.\u00a0 Electron recoils are easily identified and rejected.\u00a0 Charged particles can interact with nuclei as well, but the amount of energy deposited is below the threshold of the detectors.\u00a0 The most problematic background events come from neutron scatters.\u00a0 Both WIMPs and neutrons are electrically neutral, making them invisible to the electronic structure of the detectors; they both scatter primarily from atomic nuclei.\u00a0 Various techniques are used to identify neutrons, and reject them as background.\u00a0 However, before a method is put to use, particle-transport Monte Carlo simulations are utilized to determine the method\u2019s effectiveness.<\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 The second phase of CDMS will be conducted in a mine deep underground.\u00a0 The advantage of this is that the surrounding rock shields much of the cosmic rays that would otherwise shower the detectors with background events.\u00a0 However, there is a process of neutron production that is particularly difficult to reject.\u00a0 In this process, residual high-energy muons interact with the surrounding rock of the mine.\u00a0 The resulting \u201ccascade\u201d produces many different subatomic particles, including neutrons.\u00a0 The other subatomic particles produced carry electric charges, and rarely travel through the rock into the mine.\u00a0 A proposed method to reject these neutrons is to embed the surrounding rock with streamer tubes that can detect charged particles.\u00a0 If a nuclear recoil is seen in the detector that coincides with a signal in the streamer tubes, that event can be rejected.\u00a0 A simulation of this method must be performed to determine what percentage of these neutron cascades could be rejected.<\/p>\n","protected":false},"excerpt":{"rendered":"
Aaron Manalaysay with Dan AkeribMonte Carlo Simulation of a Neutron Rejection Technique in Dark Matter Detection\u00a0<\/p>\n
The Cryogenic Dark Matter Search (CDMS) attempts to detect dark matter in the form of Weakly Interacting Massive Particles, or WIMPs.\u00a0 The project uses low-temperature devices to detect these particles via scattering from nuclei.\u00a0 Such experiments involve considerable background events, and much effort is devoted to developing ways to discriminate WIMP scatters from other sources of particles.\u00a0 Most subatomic particles that reach the detectors are electrically charged, and thus interact with the electrons of the detectors.\u00a0 Electron recoils are easily identified and rejected.\u00a0<\/p>\n