Projected WIMP sensitivity of the LUX-ZEPLIN dark matter experiment

LUX-ZEPLIN (LZ) is a next-generation dark matter direct detection experiment that will operate 4850 feet underground at the Sanford Underground Research Facility (SURF) in Lead, South Dakota, USA. Using a two-phase xenon detector with an active mass of 7 tonnes, LZ will search primarily for low-energy interactions with weakly interacting massive particles (WIMPs), which are hypothesized to make up the dark matter in our galactic halo. In this paper, the projected WIMP sensitivity of LZ is presented based on the latest background estimates and simulations of the detector. For a 1000 live day run using a 5.6-tonne fiducial mass, LZ is projected to exclude at 90% confidence level spin-independent WIMP-nucleon cross sections above 1.4 × 10-48cm2 for a 40 GeV/c2 mass WIMP. Additionally, a 5σ discovery potential is projected, reaching cross sections below the exclusion limits of recent experiments. For spin-dependent WIMP-neutron(-proton) scattering, a sensitivity of 2.3 × 10−43 cm2 (7.1 × 10−42 cm2) for a 40 GeV/c2 mass WIMP is expected. With underground installation well underway, LZ is on track for commissioning at SURF in 2020

Search for annual and diurnal rate modulations in the LUX experiment

Various dark matter models predict annual and diurnal modulations of dark matter interaction rates in Earth-based experiments as a result of the Earth’s motion in the halo. Observation of such features can provide generic evidence for detection of dark matter interactions. This paper reports a search for both annual and diurnal rate modulations in the LUX dark matter experiment using over 20 calendar months of data acquired between 2013 and 2016. This search focuses on electron recoil events at low energies, where leptophilic dark matter interactions are expected to occur and where the DAMA experiment has observed a strong rate modulation for over two decades. By using the innermost volume of the LUX detector and developing robust cuts and corrections, we obtained a stable event rate of 2.3±0.2  cpd/keVee/tonne, which is among the lowest in all dark matter experiments. No statistically significant annual modulation was observed in energy windows up to 26  keVee. Between 2 and 6  keVee, this analysis demonstrates the most sensitive annual modulation search up to date, with 9.2σ tension with the DAMA/LIBRA result. We also report no observation of diurnal modulations above 0.2  cpd/keVee/tonne amplitude between 2 and 6  keVee.Various dark matter models predict annual and diurnal modulations of dark matter interaction rates in Earth-based experiments as a result of the Earth's motion in the halo. Observation of such features can provide generic evidence for detection of dark matter interactions. This paper reports a search for both annual and diurnal rate modulations in the LUX dark matter experiment using over 20 calendar months of data acquired between 2013 and 2016. This search focuses on electron recoil events at low energies, where leptophilic dark matter interactions are expected to occur and where the DAMA experiment has observed a strong rate modulation for over two decades. By using the innermost volume of the LUX detector and developing robust cuts and corrections, we obtained a stable event rate of 2.3$\pm$0.2~cpd/keV$_{\text{ee}}$/tonne, which is among the lowest in all dark matter experiments. No statistically significant annual modulation was observed in energy windows up to 26~keV$_{\text{ee}}$. Between 2 and 6~keV$_{\text{ee}}$, this analysis demonstrates the most sensitive annual modulation search up to date, with 9.2$\sigma$ tension with the DAMA/LIBRA result. We also report no observation of diurnal modulations above 0.2~cpd/keV$_{\text{ee}}$/tonne amplitude between 2 and 6~keV$_{\text{ee}}$

Measurement of the gamma ray background in the Davis Cavern at the Sanford Underground Research Facility

Deep underground environments are ideal for low background searches due to the attenuation of cosmic rays by passage through the earth. However, they are affected by backgrounds from γ-rays emitted by 40K and the 238U and 232Th decay chains in the surrounding rock. The LUX-ZEPLIN (LZ) experiment will search for dark matter particle interactions with a liquid xenon TPC located within the Davis campus at the Sanford Underground Research Facility, Lead, South Dakota, at the 4,850-foot level. In order to characterise the cavern background, in-situ γ-ray measurements were taken with a sodium iodide detector in various locations and with lead shielding. The integral count rates (0--3300~keV) varied from 596~Hz to 1355~Hz for unshielded measurements, corresponding to a total flux in the cavern of 1.9±0.4~γ cm−2s−1. The resulting activity in the walls of the cavern can be characterised as 220±60~Bq/kg of 40K, 29±15~Bq/kg of 238U, and 13±3~Bq/kg of 232Th

EVALUATION OF THE PROGNOSTIC VALUE OF THE EXPRESSION OF EPIDERMAL GROWTH FACTOR RECEPTORS IN BLADDER CANCER

Objectives To evaluate the role and prognostic value of the expression of epidermal growth factor receptors (EGFR) in serum and urine for the detection of human bladder cancer. Patients and Methods The study comprised 30 patients with newly diagnosed transitional cell carcinoma of the bladder and 10 normal volunteers. The patients' age ranged from 42 to 76 years. The serum and urinary EGFR levels were evaluated using the ELISA technique. An indirect haemoagglutination (IHA) test was used for the detection of bilharzial antibodies. Cystoscopy, tumor resection and bimanual examination under anaesthesia were carried out for every patient. The patients were divided into 4 groups: Group A: 10 healthy individuals serving as a control group, Group B: 7 patients with grade I bladder cancer, Group C: 10 patients with grade II bladder cancer and Group D: 13 patients with grade III bladder cancer. Results Bilharziasis was recorded in 33 patients, 6 of them were in the control group. A comparison between the bilharzial and non-bilharzial patients did not reveal any significant difference in the serum EGFR expression (46.47 ± 32.23 and 36 ± 38.22 fmol/ml, respectively) nor in the urinary EGFR expression (45.42 ± 29.78 and 41 ± 31.16 fmol/ml, respectively). None of the patients with grade I bladder cancer was found to have stage T3 and T4 cancer, while all the patient with grade II and grade III cancer had invasive cancer (> Ta). The mean values of urinary and serum levels of EGFR in the control group were 12.37 ± 7.21 and 11.9 ± 8.17 fmol/ml, respectively, while the mean values of urinary and serum levels of EGFR in the cancer patients were 46.47 ± 32.23 fmol/ml and 45.4 ± 29.78 fmol/ml, respectively, which represents a significant increase in the serum and urinary EGFR in the cancer patients as compared to the control goup. In addition, a stepwise increase in the serum and urinary EGFR was noted with the cancer grade increasing from grade I to III. The best cut-off values for serum and urinary EGFR were 22 fmol/ml and 25 fmol/ml, respectively. The best cut-off point for the serum EGFR level had a sensitivity of 83.3%, a specificity of 90% and an accuracy of 85%, while the best cut-off point for the urinary EGFR level had a sensitivity of 80%, a specificity of 90% and an accuracy of 82.5%. Conclusion Resultsof the present study suggest that high levels of EGFR in the serum and urine of patients with bladder cancer are related to various malignant histological features (tumor grade) and invasiveness of bladder cancer. In the future, the evaluation of urinary and serum EGFR might help in the prediction of recurrence rate, response to systemic treatment and in the screening of bladder tumors. African Journal of Urology Vol. 7 No. 1 (Jan 2001): pp 20-26 Key Wordsbladder cancer, epidermal growth factor receptors, tumors marker