31 research outputs found
Direct Dark Matter Searches with CDMS and XENON
The Cryogenic Dark Matter Search (CDMS) and XENON experiments aim to directly
detect dark matter in the form of weakly interacting massive particles (WIMPs)
via their elastic scattering on the target nuclei. The experiments use
different techniques to suppress background event rates to the minimum, and at
the same time, to achieve a high WIMP detection rate. The operation of
cryogenic Ge and Si crystals of the CDMS-II experiment in the Soudan mine
yielded the most stringent spin-independent WIMP-nucleon cross-section
(~10^{-43} cm^2) at a WIMP mass of 60 GeV/c^2. The two-phase xenon detector of
the XENON10 experiment is currently taking data in the Gran Sasso underground
lab and promising preliminary results were recently reported. Both experiments
are expected to increase their WIMP sensitivity by a one order of magnitude in
the scheduled science runs for 2007.Comment: appears in the proceedings of the 36th COSPAR Scientific Assembly in
Beijing, July 200
Direct detection prospects of dark vectors with xenon-based dark matter experiments
Dark matter experiments primarily search for the scattering of WIMPs on
target nuclei of well shielded underground detectors. The results from liquid
scintillator experiments furthermore provide precise probes of very light and
very weakly coupled particles that may be absorbed by electrons. In these
proceedings we summarize previously obtained constraints on long-lived dark
matter vector particles (dark photons) in the keV mass range. In
addition, we provide a first projected sensitivity reach for the upcoming
XENON1T dark matter search to detect dark photons.Comment: 5 pages, 1 figure; proceedings of the European Physical Society
Conference on High Energy Physics 2015 (EPS-HEP 2015), Vienna, Austria;
reference adde
Reward-Directed Conditional Diffusion: Provable Distribution Estimation and Reward Improvement
We explore the methodology and theory of reward-directed generation via
conditional diffusion models. Directed generation aims to generate samples with
desired properties as measured by a reward function, which has broad
applications in generative AI, reinforcement learning, and computational
biology. We consider the common learning scenario where the data set consists
of unlabeled data along with a smaller set of data with noisy reward labels.
Our approach leverages a learned reward function on the smaller data set as a
pseudolabeler. From a theoretical standpoint, we show that this directed
generator can effectively learn and sample from the reward-conditioned data
distribution. Additionally, our model is capable of recovering the latent
subspace representation of data. Moreover, we establish that the model
generates a new population that moves closer to a user-specified target reward
value, where the optimality gap aligns with the off-policy bandit regret in the
feature subspace. The improvement in rewards obtained is influenced by the
interplay between the strength of the reward signal, the distribution shift,
and the cost of off-support extrapolation. We provide empirical results to
validate our theory and highlight the relationship between the strength of
extrapolation and the quality of generated samples
Low Energy Electronic Recoils and Single Electron Detection with a Liquid Xenon Proportional Scintillation Counter
Liquid xenon (LXe) is a well-studied detector medium to search for rare
events in dark matter and neutrino physics. Two-phase xenon time projection
chambers (TPCs) can detect electronic and nuclear recoils with energy down to
kilo-electron volts (keV). In this paper, we characterize the response of a
single-phase liquid xenon proportional scintillation counter (LXePSC), which
produces electroluminescence directly in the liquid, to detect electronic
recoils at low energies. Our design uses a thin (10 - 25 m diameter),
central anode wire in a cylindrical LXe target where ionization electrons,
created from radiation particles, drift radially towards the anode, and
electroluminescence is produced. Both the primary scintillation (S1) and
electroluminescence (S2) are detected by photomultiplier tubes (PMTs)
surrounding the LXe target. Up to 17 photons are produced per electron,
obtained with a 10 m diameter anode wire, allowing for the highly
efficient detection of electronic recoils from beta decays of a tritium source
down to roughly 1 keV. Single electrons, from photo-emission of the cathode
wires, are observed at a gain of 1.8 photoelectrons (PE) per electron. The
delayed signals following the S2 signals are dominated by single-photon-like
hits, without evidence for electron signals observed in the two-phase xenon
TPCs. We discuss the potential application of such a LXePSC for reactor
neutrino detection via Coherent Elastic Neutrino Nucleus Scattering
(CENS).Comment: 18 pages, 17 figure
Low-mass dark matter search results from full exposure of PandaX-I experiment
We report the results of a weakly-interacting massive particle (WIMP) dark
matter search using the full 80.1\;live-day exposure of the first stage of the
PandaX experiment (PandaX-I) located in the China Jin-Ping Underground
Laboratory. The PandaX-I detector has been optimized for detecting low-mass
WIMPs, achieving a photon detection efficiency of 9.6\%. With a fiducial liquid
xenon target mass of 54.0\,kg, no significant excess event were found above the
expected background. A profile likelihood analysis confirms our earlier finding
that the PandaX-I data disfavor all positive low-mass WIMP signals reported in
the literature under standard assumptions. A stringent bound on the low mass
WIMP is set at WIMP mass below 10\,GeV/c, demonstrating that liquid xenon
detectors can be competitive for low-mass WIMP searches.Comment: v3 as accepted by PRD. Minor update in the text in response to
referee comments. Separating Fig. 11(a) and (b) into Fig. 11 and Fig. 12.
Legend tweak in Fig. 9(b) and 9(c) as suggested by referee, as well as a
missing legend for CRESST-II legend in Fig. 12 (now Fig. 13). Same version as
submitted to PR