Liquid xenon detector physics with XENON1T and HeXe: electric noise stability, background discrimination studies and measurements of the scintillation pulse shape

Liquefied xenon (LXe) is a popular detection medium for experiments searching for rare interactions proposed by beyond the Standard Model theories. It is employed in dual-phase time projection chambers (TPCs) used by experiments such as XENON1T, which attempt to measure particle dark matter interactions as well as the neutrinoless double-beta decay. A precise understanding of the processes behind the signals of such detectors is necessary to discriminate between background and signal events as well as possible. This work presents analyses regarding LXe TPCs physics. In the first part, the temporal evolution of electric noise in the XENON1T experiment is examined. Furthermore, a selection criterion, which has been developed to exclude interactions happening in the TPC’s gas phase, is extended to higher energy scales. Finally, it is investigated whether the LXe scintillation pulse shape allows to discriminate between nuclear recoils and background electronic recoils which originate from decays in or on TPC reflector panels. The pulse shape is also the topic of the second and final part. There, its electric field strength dependence is measured, using the TPC of the HeidelbergXenon (HeXe) system, for conversion electrons coming from 83mKr decays as well as for alpha-particles from decays of 222Rn and daughters

Transmission of xenon scintillation light through PTFE

Polytetrafluoroethylene (PTFE), also known as Teflon, is a common material used in the construction of liquid xenon detectors due to its high reflectivity for the VUV scintillation light of xenon. We present transmission measurements of PTFE for xenon scintillation light with peak emission at a wavelength of 175 nm. PTFE discs of different thicknesses are installed in front of a photosensor in two setups. One is filled with gaseous xenon, the other with liquid xenon. The measurements performed with the gaseous xenon setup at room temperature yield a transmission coefficient of $\lambda = \bigl(350{{}^{+60}_{~-0}}{}\,{\mathrm{(sys)}}\,\pm\, 50\,{\mathrm{(stat)}}\bigr)\,\mathrm{\mu m}$. This is found to be in agreement with the observations made using the liquid xenon setup.Comment: 12 pages, 5 figures, 2 tables; accepted for publication in JINS

Scintillation decay-time constants for alpha particles and electrons in liquid xenon

Understanding liquid xenon scintillation and ionization processes is of great interest to improve analysis methods in current and future detectors. In this paper, we investigate the dynamics of the scintillation process for excitation by $\mathcal{O}$(10 keV) electrons from a $^{83m}$Kr source and $\mathcal{O}$(6 MeV) $\alpha$-particles from a $^{222}$Rn source, both mixed with the xenon target. The single photon sampling method is used to record photon arrival times in order to obtain the corresponding time distributions for different applied electric fields between about 0.8 V/cm to 1.2 kV/cm. Energy and field dependences of the signals which are observed in the results are discussed.Comment: 11 pages, 9 figures; replaced with published manuscript versio

Characterization of alpha and beta interactions in liquid xenon

Liquid xenon based detectors have achieved great sensitivities in rare event searches. Precise knowledge of the scintillation and ionization responses of the medium is essential to correctly model different interaction types in the detector including both signal and background-like ones. The response of liquid xenon to low energy electrons and to alpha particles has been studied in the Heidelberg Xenon (HeXe) dual-phase xenon TPC. We determine the light and charge signal yields for keV-energy electrons and MeV-energy alpha particles as well as the electron drift velocity for electric drift fields between 7.5 and 1640 V/cm. A three dimensional simulation using COMSOL Multiphysics(R) is used to characterize the applied drift field and its homogeneity.Comment: 16 pages, 21 figures. Associated data is available under https://doi.org/10.5281/zenodo.552521

First time-resolved measurement of infrared scintillation light in gaseous xenon

Xenon is a widely used detector target material due to its excellent scintillation properties in the ultraviolet (UV) spectrum. The additional use of infrared (IR) scintillation light could improve future detectors. However, a comprehensive characterization of the IR component is necessary to explore its potential. We report on the first measurement of the time profile of the IR scintillation response of gaseous xenon. Our setup consists of a gaseous xenon target irradiated by an alpha particle source and is instrumented with one IR- and two UV-sensitive photomultiplier tubes. Thereby, it enables IR timing measurements with nanosecond resolution and simultaneous measurement of UV and IR signals. We find that the IR light yield is in the same order of magnitude as the UV yield. We observe that the IR pulses can be described by a fast and a slow component and demonstrate that the size of the slow component decreases with increasing levels of impurities in the gas. Moreover, we study the IR emission as a function of pressure. These findings confirm earlier observations and advance our understanding of the IR scintillation response of gaseous xenon, which could have implications for the development of novel xenon-based detectors.Comment: 11 pages, 10 figure

AxFoundation/strax: v1.5.4

What's Changed Split compare_metadata into utils.compare_meta by @dachengx in https://github.com/AxFoundation/strax/pull/754 Change endtime - time >= 0 to endtime >= time by @JYangQi00 in https://github.com/AxFoundation/strax/pull/756 Mandatorily wrap _read_chunk in a check_chunk_n decorator by @dachengx in https://github.com/AxFoundation/strax/pull/758 New Contributors @JYangQi00 made their first contribution in https://github.com/AxFoundation/strax/pull/756 Full Changelog: https://github.com/AxFoundation/strax/compare/v1.5.3...v1.5.

Smoking in public places in six European countries: Findings from the EUREST-PLUS ITC Europe Survey

INTRODUCTION Surveillance of tobacco consumption in public places is an important measure to evaluate the impact of tobacco control interventions over time. The objective of this study was to estimate the prevalence of smoking as seen by smokers and their smoking behaviour in public places, in six European countries. METHODS We used baseline data of the International Tobacco Control Six European countries (ITC 6E) Survey, part of the EUREST-PLUS Project, conducted in 2016 in national representative samples of about 1000 adult smokers aged 18 years and older in Germany, Greece, Hungary, Poland, Romania and Spain. For each setting (workplaces, restaurants, bars/pubs and discos) participants were asked whether they had seen someone smoking during their last visit there and whether they too had smoked there. We report the overall and by-country weighted prevalence of seeing someone smoking and the smokers’ own smoking behaviour at each setting. We also assess the relationship between seeing someone smoking and smoking themselves at these settings. RESULTS The prevalence of smoking as seen by smokers was 18.8% at workplaces, with high variability among countries (from 4.7% in Hungary to 40.8% in Greece). Among smokers visiting leisure facilities in the last year, during their last visit 22.7% had seen someone smoking inside restaurants and 12.2% had smoked themselves there, while for bars/pubs the corresponding prevalences were 33.9% and 20.4%, and inside discos 44.8% and 34.8%. CONCLUSIONS Smoking is still prevalent at leisure facilities, particularly at discos in Europe, with high variability among countries. More extensive awareness campaigns and stricter enforcement are needed to increase the compliance of smokefree regulations, especially in leisure facilities

Correlates of the support for smoke-free policies among smokers: A cross-sectional study in six European countries of the EUREST-PLUS ITC EUROPE SURVEYS

INTRODUCTION This report describes the support for smoke-free policies in different settings among smokers in six European countries and the relationship between their opinions about the places where smoking should be banned and their beliefs about the harms of secondhand smoke to non-smokers. METHODS A cross-sectional survey (the ITC 6 European Country Survey, part of the EUREST-PLUS Project) was conducted using nationally representative samples of adult smokers in Germany, Greece, Hungary, Poland, Romania and Spain (n=6011). We describe the prevalence of agreement and support for smoke-free policies in different settings according to sociodemographics, smoking characteristics and beliefs about the danger of secondhand smoke to non-smokers. RESULTS There was high agreement with smoking regulations in cars with preschool children and in schoolyards of primary/secondary schools (>90% overall) and low agreement with banning smoking in outdoor terraces of bars/pubs (8.6%; 95% CI: 7.5%-9.8%) and restaurants (10.1%; 95% CI: 8.9%-11.4%). The highest support for complete smoking bans inside public places came from smokers in Poland, among women, people aged >= 25 years, who had low nicotine dependence, and who tried to quit smoking in the last 12 months. About 78% of participants agreed that tobacco smoke is dangerous to non-smokers, ranging from 63.1% in Hungary to 88.3% in Romania; the highest agreement was noted among women, the 25-54 age groups, those with higher education, low cigarette dependence, and those who tried to quit in the last 12 months. The support for complete smoking bans in public places was consistently higher among smokers who agreed that secondhand smoke is dangerous to non-smokers. CONCLUSIONS Smokers in six European countries declared strong support for smoke-free policies in indoor settings and in settings with minors but low support in outdoor settings, particularly leisure facilities. More education is needed to increase the awareness about the potential exposure to secondhand smoke in specific outdoor areas