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The physics of background discrimina...

Dahl, Carl Eric.

The physics of background discrimination in liquid xenon, and first results from Xenon10 in the hunt for WIMP dark matter.

Record Type:	Electronic resources : Monograph/item
Title/Author:	The physics of background discrimination in liquid xenon, and first results from Xenon10 in the hunt for WIMP dark matter.
Author:	Dahl, Carl Eric.
Description:	182 p.
Notes:	Source: Dissertation Abstracts International, Volume: 70-07, Section: B, page: 4234.
Notes:	Adviser: Tom Shutt.
Contained By:	Dissertation Abstracts International70-07B.
Subject:	Physics, Astronomy and Astrophysics.
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3364532
ISBN:	9781109255294

The physics of background discrimination in liquid xenon, and first results from Xenon10 in the hunt for WIMP dark matter.
Dahl, Carl Eric.

The physics of background discrimination in liquid xenon, and first results from Xenon10 in the hunt for WIMP dark matter. - 182 p.

Source: Dissertation Abstracts International, Volume: 70-07, Section: B, page: 4234.

Thesis (Ph.D.)--Princeton University, 2009.

The WIMP limit set by the Xenon10 experiment in 2007 signals a new era in direct detection of dark matter, with several large-scale liquid target detectors now under construction. A major challenge in these detectors will be to understand backgrounds at the level necessary to claim a positive WIMP signal. In liquid xenon, these backgrounds are dominated by electron recoils, which may be distinguished from the WIMP signal (nuclear recoils) by their higher charge-to-light ratio. During the construction and operation of Xenon10, the prototype detector Xed probed the physics of this discrimination.

ISBN: 9781109255294Subjects--Topical Terms:

227131
Physics, Astronomy and Astrophysics.

The physics of background discrimination in liquid xenon, and first results from Xenon10 in the hunt for WIMP dark matter.
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100 1 $a Dahl, Carl Eric. $3 384286
245 1 4 $a The physics of background discrimination in liquid xenon, and first results from Xenon10 in the hunt for WIMP dark matter.
300 $a 182 p.
500 $a Source: Dissertation Abstracts International, Volume: 70-07, Section: B, page: 4234.
500 $a Adviser: Tom Shutt.
502 $a Thesis (Ph.D.)--Princeton University, 2009.
520 $a The WIMP limit set by the Xenon10 experiment in 2007 signals a new era in direct detection of dark matter, with several large-scale liquid target detectors now under construction. A major challenge in these detectors will be to understand backgrounds at the level necessary to claim a positive WIMP signal. In liquid xenon, these backgrounds are dominated by electron recoils, which may be distinguished from the WIMP signal (nuclear recoils) by their higher charge-to-light ratio. During the construction and operation of Xenon10, the prototype detector Xed probed the physics of this discrimination.
520 $a Particle interactions in liquid xenon both ionize and excite xenon atoms, giving charge and scintillation signals, respectively. Some fraction of ions recombine, reducing the charge signal and creating additional scintillation. The charge-to-light ratio, determined by the initial exciton-ion ratio and the ion recombination fraction, provides the basis for discrimination between electron and nuclear recoils. Intrinsic fluctuations in the recombination fraction limit discrimination.
520 $a Changes in recombination induce an exact anti-correlation between charge and light, and when calibrated this anti-correlation distinguishes recombination fluctuations from uncorrelated fluctuations in the measured signals. We determine the mean recombination and recombination fluctuations as a function of energy and applied field for electron and nuclear recoils, finding that recombination fluctuations are already the limiting factor for discrimination above &sim;12 keVr (nuclear recoil energy). Below 12 keVr statistical fluctuations in the number of scintillation photons counted dominate, and we project a x6 improvement in background rejection with a x2 increase in light collection efficiency.
520 $a We also build a simple recombination model that successfully reproduces the mean recombination in electron and nuclear recoils, including the surprising reversal of the expected trend for recombination with ionization density in low energy electron recoils. The model also reproduces the measured recombination fluctuations to within a factor of two at high energies. Surprisingly, the model suggests that recombination at low energies is independent of ionization density, and our observed discrimination is due not to the different stopping powers of electrons and nuclei as was thought, but rather to a different initial exciton-ion ratio. We suggest two possible physical models for this new result.
590 $a School code: 0181.
650 4 $a Physics, Astronomy and Astrophysics. $3 227131
650 4 $a Physics, Elementary Particles and High Energy. $3 227490
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710 2 $a Princeton University. $3 212488
773 0 $t Dissertation Abstracts International $g 70-07B.
790 1 0 $a Shutt, Tom, $e advisor
790 $a 0181
791 $a Ph.D.
792 $a 2009
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3364532