1,587 research outputs found
A Prototype Detector for Directional Measurement of the Cosmogenic Neutron Flux
This paper describes a novel directional neutron detector prototype. The low
pressure time projection chamber uses a mix of helium and CF4 gases. The
detector reconstructs the energy and angular distribution of fast neutron
recoils. This paper reports results of energy calibration using an alpha source
and angular reconstruction studies using a collimated neutron source. The best
performance is obtained with a 12.5% CF4 gas mixture. At low energies the
target for fast neutrons transitions is primarily helium, while at higher
energies, the fluorine contributes as a target. The reconstruction efficiency
is both energy and target dependent. For neutrons with energies less than 20
MeV, the reconstruction efficiency is ~40% for fluorine recoils and ~60% for
helium recoils.Comment: final versio
First Dark Matter Search Results from a Surface Run of the 10-L DMTPC Directional Dark Matter Detector
The Dark Matter Time Projection Chamber (DMTPC) is a low pressure (75 Torr
CF4) 10 liter detector capable of measuring the vector direction of nuclear
recoils with the goal of directional dark matter detection. In this paper we
present the first dark matter limit from DMTPC. In an analysis window of 80-200
keV recoil energy, based on a 35.7 g-day exposure, we set a 90% C.L. upper
limit on the spin-dependent WIMP-proton cross section of 2.0 x 10^{-33} cm^{2}
for 115 GeV/c^2 dark matter particle mass.Comment: accepted for publication in Physics Letters
A Measurement of Photon Production in Electron Avalanches in CF4
This paper presents a measurement of the ratio of photon to electron
production and the scintillation spectrum in a popular gas for time pro jection
chambers, carbon tetrafluoride (CF4), over the range of 200 to 800 nm; the
ratio is measured to be 0.34+/-0.04. This result is of particular importance
for a new generation of dark matter time projection chambers with directional
sensitivity which use CF4 as a fill gas.Comment: 19 pages, including appendix. 8 figure
Background Rejection in the DMTPC Dark Matter Search Using Charge Signals
The Dark Matter Time Projection Chamber (DMTPC) collaboration is developing
low-pressure gas TPC detectors for measuring WIMP-nucleon interactions. Optical
readout with CCD cameras allows for the detection for the daily modulation in
the direction of the dark matter wind, while several charge readout channels
allow for the measurement of additional recoil properties. In this article, we
show that the addition of the charge readout analysis to the CCD allows us too
obtain a statistics-limited 90% C.L. upper limit on the rejection factor
of for recoils with energies between 40 and 200
keV. In addition, requiring coincidence between charge signals
and light in the CCD reduces CCD-specific backgrounds by more than two orders
of magnitude.Comment: 8 pages, 6 figures. For proceedings of DPF 2011 conferenc
A Background-Free Direction-Sensitive Neutron Detector2 A Background-Free Direction-Sensitive Neutron Detector
We show data from a new type of detector that can be used to determine
neutron flux, energy distribution, and direction of neutron motion for both
fast and thermal neutrons. Many neutron detectors are plagued by large
backgrounds from x-rays and gamma rays, and most current neutron detectors lack
single-event energy sensitivity or any information on neutron directionality.
Even the best detectors are limited by cosmic ray neutron backgrounds. All
applications (neutron scattering and radiography, measurements of solar and
cosmic ray neutron flux, measurements of neutron interaction cross sections,
monitoring of neutrons at nuclear facilities, oil exploration, and searches for
fissile weapons of mass destruction) will benefit from the improved neutron
detection sensitivity and improved measurements of neutron properties made
possible by this detector. The detector is free of backgrounds from x-rays,
gamma rays, beta particles, relativistic singely charged particles and cosmic
ray neutrons. It is sensitive to thermal neutrons, fission neutrons, and high
energy neutrons, with detection features distinctive for each energy range. It
is capable of determining the location of a source of fission neutrons based on
characteristics of elastic scattering of neutrons by helium nuclei. The
detector we have constructed could identify one gram of reactor grade
plutonium, one meter away, with less than one minute of observation time.Comment: 17 pages, 8 figures, Accepted by NI
Charge amplification concepts for direction-sensitive dark matter detectors
Direction measurement of weakly interacting massive particles in
time-projection chambers can provide definite evidence of their existence and
help to determine their properties. This article demonstrates several concepts
for charge amplification in time-projection chambers that can be used in
direction-sensitive dark matter search experiments. We demonstrate
reconstruction of the 'head-tail' effect for nuclear recoils above 100keV, and
discuss the detector performance in the context of dark matter detection and
scaling to large detector volumes.Comment: 15 pages, 9 figure
Data acquisition electronics and reconstruction software for directional detection of Dark Matter with MIMAC
Directional detection of galactic Dark Matter requires 3D reconstruction of
low energy nuclear recoils tracks. A dedicated acquisition electronics with
auto triggering feature and a real time track reconstruction software have been
developed within the framework of the MIMAC project of detector. This
auto-triggered acquisition electronic uses embedded processing to reduce data
transfer to its useful part only, i.e. decoded coordinates of hit tracks and
corresponding energy measurements. An acquisition software with on-line
monitoring and 3D track reconstruction is also presented.Comment: 17 pages, 12 figure
Gaseous Dark Matter Detectors
Dark Matter detectors with directional sensitivity have the potential of
yielding an unambiguous positive observation of WIMPs as well as discriminating
between galactic Dark Matter halo models. In this article, we introduce the
motivation for directional detectors, discuss the experimental techniques that
make directional detection possible, and review the status of the experimental
effort in this field.Comment: 19 pages, review on gaseous directional dark matter detectors
submitted to New Journal of Physic
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