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COUPP Collaboration,
E. Behnke,
T. Benjamin,
S. J. Brice,
D. Broemmelsiek,
J. I. Collar,
P. S. Cooper,
M. Crisler,
C. E. Dahl,
D. Fustin, [......],
W. H. Lippincott,
T. Moan,
T. Nania,
R. Neilson,
E. Ramberg,
A. E. Robinson,
A. Sonnenschein,
E. Vázquez-Jáuregui,
R. A. Rivera,
L. Uplegger
[show abstract]
[hide abstract]
ABSTRACT: We have directly measured the energy threshold and efficiency for bubble
nucleation from iodine recoils in a CF3I bubble chamber in the energy range of
interest for a dark matter search. These interactions cannot be probed by
standard neutron calibration methods, so we develop a new technique by
observing the elastic scattering of 12 GeV/c negative pions. The pions are
tracked with a silicon pixel telescope and the reconstructed scattering angle
provides a measure of the nuclear recoil kinetic energy. The bubble chamber was
operated with a nominal threshold of (13.6+-0.6) keV. Interpretation of the
results depends on the response to fluorine and carbon recoils, but in general
we find agreement with the predictions of the classical bubble nucleation
theory. This measurement confirms the applicability of CF3I as a target for
spin-independent dark matter interactions and represents a novel technique for
calibration of superheated fluid detectors.
04/2013;
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E. Behnke,
J. Behnke,
S. J. Brice,
D. Broemmelsiek,
J. I. Collar,
A. Conner,
P. S. Cooper,
M. Crisler,
C. E. Dahl,
D. Fustin, [......],
M. Hu,
I. Levine,
W. H. Lippincott,
T. Moan,
T. Nania,
E. Ramberg,
A. E. Robinson,
A. Sonnenschein,
M. Szydagis,
E. Vázquez-Jáuregui
[show abstract]
[hide abstract]
ABSTRACT: New data are reported from the operation of a 4.0 kg CF$_{3}$I bubble chamber
in the 6800-foot-deep SNOLAB underground laboratory. The effectiveness of
ultrasound analysis in discriminating alpha-decay background events from single
nuclear recoils has been confirmed, with a lower bound of $>$99.3% rejection of
alpha-decay events. Twenty single nuclear recoil event candidates and three
multiple bubble events were observed during a total exposure of 553 kg-days
distributed over three different bubble nucleation thresholds. The effective
exposure for single bubble recoil-like events was 437.4 kg-days. A neutron
background internal to the apparatus, of known origin, is estimated to account
for five single nuclear recoil events and is consistent with the observed rate
of multiple bubble events. This observation provides world best direct
detection constraints on WIMP-proton spin-dependent scattering for WIMP masses
$>$20 GeV/c$^{2}$ and demonstrates significant sensitivity for spin-independent
interactions.
04/2012;
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E Behnke,
J Behnke,
S J Brice,
D Broemmelsiek,
J I Collar,
P S Cooper,
M Crisler,
C E Dahl,
D Fustin, J Hall,
J H Hinnefeld,
M Hu,
I Levine,
E Ramberg,
T Shepherd,
A Sonnenschein,
M Szydagis
[show abstract]
[hide abstract]
ABSTRACT: Data from the operation of a bubble chamber filled with 3.5 kg of CF3I in a shallow underground site are reported. An analysis of ultrasound signals accompanying bubble nucleations confirms that alpha decays generate a significantly louder acoustic emission than single nuclear recoils, leading to an efficient background discrimination. Three dark matter candidate events were observed during an effective exposure of 28.1 kg day, consistent with a neutron background. This observation provides strong direct detection constraints on weakly interacting massive particle (WIMP)-proton spin-dependent scattering for WIMP masses >20 GeV/c2.
Physical Review Letters 01/2011; 106(2):021303. · 7.37 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: A photomultiplier (PMT) readout system has been designed for use by the cosmic ray veto systems of two warm liquid bubble chambers built at Fermilab by the Chicagoland Observatory Underground for Particle Physics (COUPP) collaboration. The systems are designed to minimize the infrastructure necessary for installation. Up to five PMTs can be daisy-chained on a single data link using standard Category 5 network cable. The cables is also serve distribute to low voltage power. High voltage is generated locally on each PMT base. Analog and digital signal processing is also performed locally. The PMT base and system controller design and performance measurements are presented.
Nuclear Science Symposium Conference Record (NSS/MIC), 2010 IEEE; 12/2010
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E. Behnke,
J. Behnke,
S. J. Brice,
D. Broemmelsiek,
J. I. Collar,
P. S. Cooper,
M. Crisler,
C. E. Dahl,
D. Fustin, J Hall,
J. H. Hinnefeld,
M. Hu,
I Levine,
E. Ramberg,
T. Shepherd,
A. Sonnenschein,
M. Szydagis
[show abstract]
[hide abstract]
ABSTRACT: Data from the operation of a bubble chamber filled with 3.5 kg of CF$_{3}$I
in a shallow underground site are reported. An analysis of ultrasound signals
accompanying bubble nucleations confirms that alpha decays generate a
significantly louder acoustic emission than single nuclear recoils, leading to
an efficient background discrimination. Three dark matter candidate events were
observed during an effective exposure of 28.1 kg-day, consistent with a neutron
background. This observation provides the strongest direct detection constraint
to date on WIMP-proton spin-dependent scattering for WIMP masses $>20$
GeV/c$^{2}$.
08/2010;
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W. J. Bolte,
J. I. Collar,
M. Crisler, J Hall,
D. Holmgren,
D. Nakazawa,
B. Odom,
K. O'Sullivan,
R Plunkett,
E. Ramberg,
A. Raskin,
A. Sonnenschein,
J. D. Vieira
[show abstract]
[hide abstract]
ABSTRACT: The viability of using a Bubble Chamber for rare event searches and in
particular for the detection of dark matter particle candidates is considered.
Techniques leading to the deactivation of inhomogeneous nucleation centers and
subsequent enhanced stability in such a detector are described. Results from
prototype trials indicate that sensitivity to low-energy nuclear recoils like
those expected from Weakly Interacting Massive Particles can be obtained in
conditions of near total insensitivity to minimum ionizing backgrounds. An
understanding of the response of superheated heavy refrigerants to these
recoils is demonstrated within the context of existing theoretical models. We
comment on the prospects for the detection of supersymmetric dark matter
particles with a large $CF_{3}I$ chamber.
03/2005;
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[show abstract]
[hide abstract]
ABSTRACT: Special effects in motion pictures largely employ image
compositing to seamlessly join picture elements together from separate
sequences. The extraction of objects such as actors from real
backgrounds rather than blue screens requires manual tracking of the
object boundary by skilled operators: an inaccurate and error-prone task
which inevitably generates a bubbling artifact. An active surface model
defined over the three dimensional spatio-temporal space is recovered
whose intersection with each image plane represents the required object
boundary. Such active surfaces are a generalisation of snake contours
common in many image processing applications. Initial crude boundaries
are drawn in end frames and key intermediate frames to construct an
initial surface. A energy minimisation process is used to iteratively
refine the location of boundaries in all frames simultaneously. User
selected edge data may also be employed to guide the crudely specified
initial contours to their correct location
Image Processing, 1997. Proceedings., International Conference on; 11/1997
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W.J. Bolte,
J.I. Collar,
M. Crisler, J. Hall,
D. Holmgren,
D. Nakazawa,
B. Odom,
K. O’Sullivan,
R. Plunkett,
E. Ramberg,
A. Raskin,
A. Sonnenschein,
J.D. Vieira
[show abstract]
[hide abstract]
ABSTRACT: The viability of using Bubble Chambers as dark matter particle detectors is considered. Techniques leading to the enhanced chamber stability needed for this new application are described in detail. Prototype trials show that sensitivity to the low-energy nuclear recoils induced by Weakly Interacting Massive Particles (WIMP) is possible in conditions of extreme insensitivity to minimum ionizing backgrounds. An understanding of detector response is demonstrated using existing theoretical models. We briefly comment on the prospects for detection of supersymmetric dark matter with large CF3I chambers.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment.
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[show abstract]
[hide abstract]
ABSTRACT: Bubble nucleation in moderately superheated liquids can be triggered by nuclear recoils from WIMPs. This phenomenon is the basis for superheated droplet detectors. The droplet technique is currently limited by insensitivity to spin-independent interactions, due to lack of heavy elements in the usual target liquids, and sensitivity to contamination of the gel by alpha emitters. As an alternative, we have developed a new type of homogeneous bubble chamber, which can contain heavy liquids, including CF3Br, CF3I, and C3F8. Detectors of this type may be scalable to large size at modest cost and could have very low backgrounds. We discuss results obtained with a 12 ml prototype and plans for a 1 liter chamber.
New Astronomy Reviews.
