299 research outputs found
Lowering the energy threshold in COSINE-100 dark matter searches
COSINE-100 is a dark matter detection experiment that uses NaI(Tl) crystal
detectors operating at the Yangyang underground laboratory in Korea since
September 2016. Its main goal is to test the annual modulation observed by the
DAMA/LIBRA experiment with the same target medium. Recently DAMA/LIBRA has
released data with an energy threshold lowered to 1 keV, and the persistent
annual modulation behavior is still observed at 9.5. By lowering the
energy threshold for electron recoils to 1 keV, COSINE-100 annual modulation
results can be compared to those of DAMA/LIBRA in a model-independent way.
Additionally, the event selection methods provide an access to a few to sub-GeV
dark matter particles using constant rate studies. In this article, we discuss
the COSINE-100 event selection algorithm, its validation, and efficiencies near
the threshold
Search for solar bosonic dark matter annual modulation with COSINE-100
We present results from a search for solar bosonic dark matter using the
annual modulation method with the COSINE-100 experiment. The results were
interpreted considering three dark sector bosons models: solar dark photon;
DFSZ and KSVZ solar axion; and Kaluza-Klein solar axion. No modulation signal
that is compatible with the expected from the models was found from a data-set
of 2.82 yr, using 61.3 kg of NaI(Tl) crystals. Therefore, we set a 90
confidence level upper limits for each of the three models studied. For the
solar dark photon model, the most stringent mixing parameter upper limit is
for dark photons with a mass of 215 eV. For the DFSZ and
KSVZ solar axion, and the Kaluza-Klein axion models, the upper limits exclude
axion-electron couplings, , above for axion mass
below 0.2 keV; and axion-photon couplings, , above GeV for an axion number density of cm. This is the first experimental search for solar dark
photons and DFSZ and KSVZ solar axions using the annual modulation method. The
lower background, higher light yield and reduced threshold of NaI(Tl) crystals
of the future COSINE-200 experiment are expected to enhance the sensitivity of
the analysis shown in this paper. We show the sensitivities for the three
models studied, considering the same search method with COSINE-200.Comment: 13 pages, 16 figure
Search for Boosted Dark Matter in COSINE-100
We search for energetic electron recoil signals induced by boosted dark
matter (BDM) from the galactic center using the COSINE-100 array of NaI(Tl)
crystal detectors at the Yangyang Underground Laboratory. The signal would be
an excess of events with energies above 4MeV over the well-understood
background. Because no excess of events are observed in a 97.7 kgyears
exposure, we set limits on BDM interactions under a variety of hypotheses.
Notably, we explored the dark photon parameter space, leading to competitive
limits compared to direct dark photon search experiments, particularly for dark
photon masses below 4MeV and considering the invisible decay mode. Furthermore,
by comparing our results with a previous BDM search conducted by the Super-
Kamionkande experiment, we found that the COSINE-100 detector has advantages in
searching for low-mass dark matter. This analysis demonstrates the potential of
the COSINE-100 detector to search for MeV electron recoil signals produced by
the dark sector particle interactions.Comment: 7 pages, 4 figure
Muon detector for the COSINE-100 experiment
The COSINE-100 dark matter search experiment has started taking physics data with the goal of performing an independent measurement of the annual modulation signal observed by DAMA/LIBRA. A muon detector was constructed by using plastic scintillator panels in the outermost layer of the shield surrounding the COSINE-100 detector. It detects cosmic ray muons in order to understand the impact of the muon annual modulation on dark matter analysis. Assembly and initial performance tests of each module have been performed at a ground laboratory. The installation of the detector in the Yangyang Underground Laboratory (Y2L) was completed in the summer of 2016. Using three months of data, the muon underground flux was measured to be 328 ± 1(stat.)± 10(syst.) muons/m2/day. In this report, the assembly of the muon detector and the results from the analysis are presented
Low Threshold Results and Limits from the DRIFT Directional Dark Matter Detector
We present results from a 54.7 live-day shielded run of the DRIFT-IId detector, the world\u27s most sensitive, directional, dark matter detector. Several improvements were made relative to our previous work including a lower threshold for detection, a more robust analysis and a tenfold improvement in our gamma rejection factor. After analysis, no events remain in our fiducial region leading to an exclusion curve for spin-dependent WIMP-proton interactions which reaches 0.28 pb at 100 GeV/c^2 a fourfold improvement on our previous work. We also present results from a 45.4 live-day unshielded run of the DRIFT-IId detector during which 14 nuclear recoil-like events were observed. We demonstrate that the observed nuclear recoil rate of 0.31+/-0.08 events per day is consistent with detection of ambient, fast neutrons emanating from the walls of the Boulby Underground Science Facility
Initial performance of the COSINE-100 experiment
COSINE is a dark matter search experiment based on an array of low background NaI(Tl) crystals located at the Yangyang underground laboratory. The assembly of COSINE-100 was completed in the summer of 2016 and the detector is currently collecting physics quality data aimed at reproducing the DAMA/LIBRA experiment that reported an annual modulation signal. Stable operation has been achieved and will continue for at least 2 years. Here, we describe the design of COSINE-100, including the shielding arrangement, the configuration of the NaI(Tl) crystal detection elements, the veto systems, and the associated operational systems, and we show the current performance of the experiment
- …