arXiv subjects

Marc Schumann

Publications and source records attributed to Marc Schumann.

At least 19 recordsLinked to original sources

arXiv2026

Doberman: a modular and distributed slow control system for small- to medium-scale experiments

We present Doberman (Detector OBsERving and Monitoring ApplicatioN), a lightweight, modular, and open-source slow control system designed for small-to medium-scale physics experiments. Doberman addresses the gap between heavyweight industrial SCADA frameworks and ad hoc laboratory solutions by providing a flexible software architecture that supports heterogeneous instrumentation, distributed deployment, automated control, and robust alarm handling. The web-based graphical user interface Doberview provides live and continuously updated visualization, configuration, and control of the entire experiment, supporting both routine operation and rapid response to exceptional conditions. Doberman has been deployed and validated in multiple experimental setups, ranging from a remotely operated underground gamma-ray spectrometer to a large, highly instrumented liquid xenon test facility with several hundred monitored quantities. Doberman and Doberview are released under permissive open-source licenses, and the software, documentation, and example device integrations are publicly available.

physics.ins-det↗

arXiv2026

Operating a large-diameter dual-phase liquid xenon TPC in the unshielded PANCAKE facility

Future liquid-xenon (LXe) based observatories for rare processes, such as XLZD, require testing of large components and sub-assemblies in cryogenic liquid or gaseous xenon environments. Here we present results from the stable operation of a shallow dual-phase LXe TPC with an inner diameter of 133.4\,cm and a height of 3.1\,cm in the unshielded PANCAKE platform, without underground suppression of cosmic-ray backgrounds. A total of 340\,kg of xenon was used in the experiment, of which 127\,kg constituted the active TPC mass. Measurements of the LXe purity-dependent electron lifetime and the electron drift velocity in LXe demonstrate that sensitive measurements to characterize the TPC performance are possible in a high-background environment, even with a very basic PMT-based light detection system. Improving this will straightforwardly reduce the TPC threshold, which was observed to be around 15\,keV for electronic recoils in TPC operation.

physics.ins-det↗

arXiv2024

Signal partitioning in superfluid ${}^4$He: a Monte Carlo approach

Superfluid ${}^4$He is an ideal candidate for the direct detection of light dark matter via nuclear recoils thanks to its low nuclear mass and the possibility to reach a low detection energy threshold by exploiting the generated quasiparticles. The design of future detectors based on this target, such as the DELight experiment, requires a proper understanding of the formation and partitioning of the signal for different energy depositions from various sources. This work presents an overview of the physical processes involved in the energy deposition of recoiling electrons and ions, and describes a Monte Carlo approach to the partitioning of the signal into different channels. Despite an overall good agreement with existing literature, differences in the region of interest for light dark matter searches below 200 eV are observed.

hep-ex↗

arXiv2024

Proportional scintillation in liquid xenon: demonstration in a single-phase liquid-only time projection chamber

The largest direct dark matter search experiments to date employ dual-phase time projection chambers (TPCs) with liquid noble gas targets. These detect both the primary photons generated by particle interactions in the liquid target, as well as proportional secondary scintillation light created by the ionization electrons in a strong electric field in the gas phase between the liquid-gas interface and the anode. In this work, we describe the detection of charge signals in a small-scale single-phase liquid-xenon-only TPC, that features the well-established TPC geometry with light readout above and below a cylindrical target. In the single-phase TPC, the proportional scintillation light (S2) is generated in liquid xenon in close proximity to 10 {\mu}m diameter anode wires. The detector was characterized and the proportional scintillation process was studied using the 32.1 keV and 9.4 keV signals from 83mKr decays. A charge gain factor g2 of up to (1.9 $\pm$ 0.3) PE/electron was reached at an anode voltage 4.4 kV higher than the gate electrode 5 mm below it, corresponding to (29 $\pm$ 6) photons emitted per ionization electron. The duration of S2 signals is dominated by electron diffusion and approaches the xenon de-excitation timescale for very short electron drift times. The electron drift velocity and the longitudinal diffusion constant were measured at a drift field of 470 V/cm. The results agree with the literature and demonstrate that a single-phase TPC can be operated successfully.

physics.ins-det↗

arXiv2023

PANCAKE: a large-diameter cryogenic test platform with a flat floor for next generation multi-tonne liquid xenon detectors

The PANCAKE facility is the world's largest liquid xenon test platform. Inside its cryostat with an internal diameter of 2.75 m, components for the next generation of liquid xenon experiments, such as DARWIN or XLZD, will be tested at their full scale. This is essential to ensure their successful operation. This work describes the facility, including its cryostat, cooling systems, xenon handling infrastructure, and its monitoring and instrumentation. The inner vessel has a flat floor, which allows the full diameter to be used with a modest amount of xenon. This is a novel approach for such a large cryostat and is of interest for future large-scale experiments, where a standard torispherical head would require tonnes of additional xenon. Our current xenon inventory of 400 kg allows a liquid depth of about 2 cm in the inner cryostat vessel. We also describe the commissioning of the facility, which is now ready for component testing.

physics.ins-det↗

arXiv2022

DELight: a Direct search Experiment for Light dark matter with superfluid helium

To reach ultra-low detection thresholds necessary to probe unprecedentedly low Dark Matter masses, target material alternatives and novel detector designs are essential. One such target material is superfluid $^4$He which has the potential to probe so far uncharted light Dark Matter parameter space at sub-GeV masses. The new ``Direct search Experiment for Light dark matter'', DELight, will be using superfluid helium as active target, instrumented with magnetic micro-calorimeters. It is being designed to reach sensitivity to masses well below 100\,MeV in Dark Matter-nucleus scattering interactions.

hep-ex↗

arXiv2022

Reduction of $^{222}$Rn-induced Backgrounds in a Hermetic Dual-Phase Xenon Time Projection Chamber

The continuous emanation of $^{222}$Rn from detector surfaces causes the dominant background in current liquid xenon time projection chambers (TPCs) searching for dark matter. A significant reduction is required for the next generation of detectors which are aiming to reach the neutrino floor, such as DARWIN. $^{222}$Rn-induced back\-grounds can be reduced using a hermetic TPC, in which the sensitive target volume is mechanically separated from the rest of the detector containing the majority of Rn-emanating surfaces. We present a hermetic TPC that mainly follows the well-established design of leading xenon TPCs and has been operated successfully over a period of several weeks. By scaling up the results achieved to the DARWIN-scale, we show that the hermetic TPC concept can reduce the $^{222}$Rn concentration to the required level, even with imperfect separation of the volumes.

physics.ins-det↗

arXiv2022

The XeBRA platform for liquid xenon time projection chamber development

XeBRA is a flexible cryogenic platform designed to perform research and development for liquid xenon detectors searching for rare events. Its extra-large outer cryostat makes it possible to install a wide variety of detector designs. We present the system, including its cryogenic, gas handling, data acquisition and slow control subsystems. Two dual phase time projection chambers with sensitive masses at the 1 kg scale have so far been operated in XeBRA. Using data from these, we determine the field-dependence of the electron drift velocity in liquid xenon. We also measure the relative charge and light yields for 41.5 keV energy deposits from Kr-83m with electric drift fields between 50 V/cm and 677 V/cm.

physics.ins-det↗

arXiv2022

GeMSE: a Low-Background Facility for Gamma-Spectrometry at Moderate Rock Overburden

The GeMSE (Germanium Material and meteorite Screening Experiment) facility operates a low-background HPGe crystal in an underground laboratory with a moderate rock overburden of 620$\,$m.w.e. in Switzerland. It has been optimized for continuous remote operation. A multi-layer passive shielding, a muon veto, and a boil-off nitrogen purge line inside the measurement cavity minimize the instrument's background rate, which decreased by 33% to (164$\pm$2)$\,$counts/day (100-2700$\,$keV) after five years of underground operation. This agrees with the prediction based on the expected decay of short-lived isotopes. A fit to the known background components, modeled via a precise simulation of the detector, shows that the GeMSE background is now muon-dominated. We also present updates towards a more accurate detection efficiency calculation for the screened samples: the thickness of the crystal's outer dead-layer is precisely determined and the efficiency can now be easily calculated for any sample geometry. The advantage of this feature is showcased via the determination of the $^{40}$K content in the screening of a complex-shaped object: a banana.

physics.ins-det↗

arXiv2021

Prospects of charge signal analyses in liquid xenon TPCs with proportional scintillation in the liquid phase

As liquid xenon TPCs increase in target mass while pursuing the direct detection of WIMP dark matter, the technical challenges arising due to their size call for new solutions and open the discussion on alternative detector concepts. Proportional scintillation in liquid xenon allows for a single-phase design evading all problems related to the liquid-gas interface and the precise gas gap required in a dual-phase TPC. Aside from a different scintillation mechanism, the successful detection- and analysis scheme of state-of-the-art experiments is maintained in this approach. We study the impact on charge signal analysis in a single-phase detector of DARWIN dimensions, where the fast timing of the proportional scintillation signal allows for the precise identification of the single electrons in the ionisation signal. Such a discrete electron-counting approach leads to a better signal resolution for low energies when compared to the classical dual-phase continuous method. The absence of the liquid-gas interface further benefits the S2-only energy resolution significantly. This reduces the uncertainties from the scintillation and signal-detection process to a level significantly below the irreducible fluctuation in the primary ionisation. Exploiting the precise electron time information further allows for a powerful single vs.~multiple site interaction discrimination with 93% rejection efficiency and 98% signal acceptance. This outperforms the design goal of the DARWIN observatory by a reduction factor of 4.2 in non-rejected multiple site neutron events.

physics.ins-det↗

arXiv2021

Direct Detection of Dark Matter -- APPEC Committee Report

This Report provides an extensive review of the experimental programme of direct detection searches of particle dark matter. It focuses mostly on European efforts, both current and planned, but does it within a broader context of a worldwide activity in the field. It aims at identifying the virtues, opportunities and challenges associated with the different experimental approaches and search techniques. It presents scientific and technological synergies, both existing and emerging, with some other areas of particle physics, notably collider and neutrino programmes, and beyond. It addresses the issue of infrastructure in light of the growing needs and challenges of the different experimental searches. Finally, the Report makes a number of recommendations from the perspective of a long-term future of the field. They are introduced, along with some justification, in the opening Overview and Recommendations section and are next summarised at the end of the Report. Overall, we recommend that the direct search for dark matter particle interactions with a detector target should be given top priority in astroparticle physics, and in all particle physics, and beyond, as a positive measurement will provide the most unambiguous confirmation of the particle nature of dark matter in the Universe.

hep-ex↗

arXiv2020

VUV Transmission of PTFE for Xenon-based Particle Detectors

Liquid xenon (LXe) based detectors for rare event searches in particle and astroparticle physics are optimized for high xenon scintillation light collection and low background rate from detector materials. Polytetrafluoroethylene (PTFE, Teflon) is commonly used to encapsulate the active LXe volume due to its high reflectance for VUV LXe scintillation light with peak emission at 178 nm. Reflectance, transmission and number of background signals arising from PTFE depend on the thickness of the PTFE detector walls. In this work, we present VUV transmission measurements for PTFE of various thicknesses often considered in the design phase of LXe detectors. PTFE samples are measured in an apparatus previously used for reflectance measurements in LXe using collimated light at a wavelength of 178 nm. Measurements in vacuum as well as gaseous xenon are described by the Kubelka and Munk model, as well as by Beer-Lambert's law for samples of $\geq 0.7\,\mathrm{mm}$ thickness, yielding a transmission coefficient of $\lambda_\text{BL} = (0.89 \pm 0.05)\,\mathrm{mm}$. The PTFE wall thickness of the XENONnT dark matter experiment was optimized by these measurements and selected as $\geq 3\,\mathrm{mm}$.

physics.ins-det↗

arXiv2019

Direct Detection of WIMP Dark Matter: Concepts and Status

The existence of dark matter as evidenced by numerous indirect observations is one of the most important indications that there must be physics beyond the Standard Model of particle physics. This article reviews the concepts of direct detection of dark matter in the form of Weakly Interacting Massive Particles (WIMPs) in ultra-sensitive detectors located in underground laboratories, discusses the expected signatures, detector concepts, and how the stringent low-background requirements are achieved. Finally, it summarizes the current status of the field and provides an outlook on the years to come.

astro-ph.CO↗

arXiv2016

A versatile and light-weight slow control system for small-scale applications

We present an open source slow control system for small and medium scale projects. Thanks to its modular and flexible design, where the various instruments are read and controlled by independent plugins, Doberman (Detector OBsERving and Monitoring ApplicatioN) can be quickly adapted for many applications, also making use of existing code or proprietary components. The system uses a SQL database to store the data from the instruments and provides an online application to display and browse through the data. It allows the modification of device settings while the program is running and features a protocol to handle exceptions, including the automated distribution of alarm messages. We present two case studies from astroparticle physics, on which Doberman is successfully deployed: a low-background screening facility installed in a remote underground laboratory and a detector R&D platform using cryogenic liquid xenon.

physics.ins-det↗

arXiv2015

Cosmogenic activation of xenon and copper

Rare event search experiments using liquid xenon as target and detection medium require ultra-low background levels to fully exploit their physics potential. Cosmic ray induced activation of the detector components and, even more importantly, of the xenon itself during production, transportation and storage at the Earth's surface, might result in the production of radioactive isotopes with long half-lives, with a possible impact on the expected background. We present the first dedicated study on the cosmogenic activation of xenon after 345 days of exposure to cosmic rays at the Jungfraujoch research station at 3470m above sea level, complemented by a study of copper which has been activated simultaneously. We have directly observed the production of 7Be, 101Rh, 125Sb, 126I and 127Xe in xenon, out of which only 125Sb could potentially lead to background for a multi-ton scale dark matter search. The production rates for five out of eight studied radioactive isotopes in copper are in agreement with the only existing dedicated activation measurement, while we observe lower rates for the remaining ones. The specific saturation activities for both samples are also compared to predictions obtained with commonly used software packages, where we observe some underpredictions, especially for xenon activation.

astro-ph.IM↗

arXiv2015

Dark matter sensitivity of multi-ton liquid xenon detectors

We study the sensitivity of multi ton-scale time projection chambers using a liquid xenon target, e.g., the proposed DARWIN instrument, to spin-independent and spin-dependent WIMP-nucleon scattering interactions. Taking into account realistic backgrounds from the detector itself as well as from neutrinos, we examine the impact of exposure, energy threshold, background rejection efficiency and energy resolution on the dark matter sensitivity. With an exposure of 200 t x y and assuming detector parameters which have been already demonstrated experimentally, spin-independent cross sections as low as $2.5 \times 10^{-49}$ cm$^2$ can be probed for WIMP masses around 40 GeV/$c^2$. Additional improvements in terms of background rejection and exposure will further increase the sensitivity, while the ultimate WIMP science reach will be limited by neutrinos scattering coherently off the xenon nuclei.

physics.ins-det↗

arXiv2015

Dark Matter 2014

This article gives an overview on the status of experimental searches for dark matter at the end of 2014. The main focus is on direct searches for weakly interacting massive particles (WIMPs) using underground-based low-background detectors, especially on the new results published in 2014. WIMPs are excellent dark matter candidates, predicted by many theories beyond the standard model of particle physics, and are expected to interact with the target nuclei either via spin-independent (scalar) or spin-dependent (axial-vector) couplings. Non-WIMP dark matter candidates, especially axions and axion-like particles are also briefly discussed.

astro-ph.CO↗

arXiv2014

Dual-Phase Liquid Xenon Detectors for Dark Matter Searches

Dual-phase time projection chambers (TPCs) filled with the liquid noble gas xenon (LXe) are currently the most sensitive detectors searching for interactions of WIMP dark matter in a laboratory-based experiment. This is achieved by combining a large, monolithic dark matter target of a very low background with the capability to localize the interaction vertex in three dimensions, allowing for target fiducialization and multiple-scatter rejection. The background in dual-phase LXe TPCs is further reduced by the simultaneous measurement of the scintillation and ionization signal from a particle interaction, which is used to distinguish signal from background signatures. This article reviews the principle of dual-phase LXe TPCs, and provides an overview about running as well as future experimental efforts.

astro-ph.IM↗