We present a newly developed instrument for 22Na-based positron-annihilation lifetime spectroscopy, designed to facilitate the simultaneous control of temperature, gas atmosphere, and humidity in a single experimental system. The spectrometer operates within a temperature range of 50–480 K and pressures from 10−6 mbar to 1.5 bars. It features a novel gas dosing chamber that allows in situ adsorption studies with gases such as but not limited to CO2, N2, Ar, O2, and their mixtures, with precise control over mixing ratios. Additionally, the device supports in situ humidity exposure, allowing for comprehensive studies of sample interactions with both humidity and humid gases. Fully automated, the system provides seamless data acquisition and environmental control, including pressure and temperature regulation. We demonstrate the instrument’s capability to elucidate alterations in the free volume of maltodextrin under humidity exposure. Additionally, we illustrate the instrument’s efficacy through case studies on CPO-27 metal-organic frameworks (MOFs), highlighting its versatility in analyzing adsorption phenomena across diverse gas adsorbates and temperatures. This state-of-the-art spectrometer stands as an indispensable tool for probing the physicochemical attributes of materials under varying conditions, providing pivotal insights into gas adsorption mechanisms and material dynamics.

The NeuLAND (New Large-Area Neutron Detector) plastic-scintillator-based time-of-flight detector for 0.1-1.6 GeV neutrons is currently under construction at the Facility for Antiproton and Ion Research (FAIR), Darmstadt, Germany. In its final configuration, NeuLAND will consist of 3,000 2.7 m x 5 cm x 5 cm big plastic scintillator bars that are read out on each end by fast timing photomultipliers. Here, data from a comprehensive study of an alternative light readout scheme using silicon photomultipliers (SiPM) are reported. For this purpose, a NeuLAND bar was instrumented on each end with a SiPM-based prototype of the same geometry as a 1" photomultiplier tube, including four 6 x 6 mm(2) SiPMs, amplifiers, high voltage supply, and microcontroller. Tests were carried out using the 35 MeV electron beam from the superconducting Electron Linac for beams with high Brilliance and low Emittance (ELBE) with its picosecond-level time jitter in two different modes of operation, namely parasitic mode with one electron per bunch and single-user mode with 1-60 electrons per bunch. Acqiris fast digitisers were used for data acquisition. In addition, off-beam tests using cosmic rays and the NeuLAND data acquisition scheme have been carried out. Typical time resolutions of sigma <= 120 ps were found for >= 95% efficiency for minimum ionising particles, improving on previous work at ELBE and exceeding the NeuLAND timing goal of sigma < 150 ps. Over a range of 10-300MeV deposited energy in the NeuLAND bar, the gain was found to deviate by <= 10% (<= 20%) from linearity for 35 mu m (75 mu m) SiPM pitch, respectively, satisfactory for calorimetric use of the full NeuLAND detector. The dark rate of the prototype studied was found to be lower than the expected cosmic-ray induced background in NeuLAND.

The development of a switch circuit to gate charge sensitive preamplifiers for use at pulsed radiation sources will be presented. This development was used for the O-16(n, alpha)C-13 reaction measurement with a Double Frisch Grid Ionization Chamber (DFGIC) at the neutron time-of-flight facility CERN n_TOF in Geneva, Switzerland. Intense instantaneous radiation which is produced in the spallation target of the n_TOF facility (gamma-flash) can saturate charge sensitive preamplifiers and prevent signals from being registered in the detection system. The switch circuit made it possible for the first time to perform a measurement with the DFGIC with gamma -flash gated off at n_TOF. Nano-second gating of charge sensitive preamplifiers has a wide range of applicability at pulsed radiation sources, where short bursts of radiation must be gated off to avoid saturation, e.g. with HPGe detectors for gamma-ray detection. Nano-second gating requires the stray-capacitance of the wideband reflective switch to be compensated to avoid a strong signal during the switch operation. Spectral analysis of the switch circuit shows that additional noise is insignificant.

The 16 O(n, α ) 13 C reaction was proposed to be measured at the neutron time-of-flight (n_TOF) facility of CERN. To this purpose, a Double Frisch Grid Ionization Chamber (DFGIC) containing the oxygen atoms as a component in the counting gas coupled with a switch device in order to prevent the charge collection from the so-called γ -flash has been developed at Helmholtz-Zentrum Dresden-Rossendorf (HZDR), in Germany. The first 16 O(n, α ) 13 C measurement without seeing the charge of the γ -flash at n_TOF has been performed in November 2018. After the electronics did not suffer from the y-flash any more, another huge charge collection was discovered. Due to the high instantaneous flux at the n_TOF facility [1] the amount of that induced charge from neutron induced background reactions was piling up so much that the recognition of 16 O(n, α ) 13 C reactions from that background was very difficult. For that reason another 16 O(n, α ) 13 C measurement at the time-of-flight facility nELBE at HZDR which has a low instantaneous flux [2], has been performed in April 2019. Both measurements from n_TOF and nELBE will be presented here.

The \(^{16}\)O(n, \({\alpha }\))\(^{13}\)C reaction, as the inverse reaction of the astrophysically important \(^{13}\)C(\({\alpha }\), n)\(^{16}\)O reaction, is proposed to be measured at the neutron time-of-flight (n_TOF) facility of CERN. To this purpose, a Double Frisch Grid Ionization Chamber (DFGIC) containing the oxygen atoms as a component in the counting gas has been developed and a prototype was constructed at Helmholtz-Zentrum Dresden-Rossendorf(HZDR), in Germany. The first in-beam tests of the detector have been performed in November 2017 in the first (EAR1) and in April 2018 in the second (EAR2) experimental areas of the n_TOF at facility.

The detection of 200–1000 MeV neutrons requires large amounts, ~100cm, of detector material because of the long nuclear interaction length of these particles. In the example of the NeuLAND neutron time-of-flight detector at FAIR, this is accomplished by using 3000 monolithic scintillator bars of 270×5×5cm3 size made of a fast plastic. Each bar is read out on the two long ends, and the needed time resolution of σt<150ps is reached with fast timing photomultipliers. In the present work, it is investigated whether silicon photomultiplier (SiPM) photosensors can be used instead. Experiments with a picosecond laser system were conducted to determine the timing response of the assembly made up of SiPM and preamplifier. The response of the full system including also the scintillator was studied using 30 MeV single electrons provided by the ELBE superconducting electron linac. The ELBE data were matched by a simple Monte Carlo simulation, and they were found to obey an inverse-square-root scaling law. In the electron beam tests, a time resolution of σt=136ps was reached with a pure SiPM readout, well within the design parameters for NeuLAND.

We show how the high charged-particle flux (1–20 kHz/cm2) expected over the 150 m2 large time-of-flight wall of the future Compressed Baryonic Matter experiment (CBM) at FAIR can be realistically handled with Multi-gap Resistive Plate Chambers (MRPCs). This crucial 100-fold increase of the chamber rate capability, as compared to that of standard MRPCs presently employed in experiments resorting to sub-100 ps timing, has been achieved thanks to the development of a new type of low-resistive doped glass. Following the encouraging results previously obtained with small counters, two types of modules (active area: ∼150 cm2) have been built at Tsinghua University with the new material. The measurements conveyed in this work, obtained with a quasi- minimum ionizing electron beam (γβ≥3), prove their suitability as the building blocks of the present hadron-identification concept of the CBM experiment. Namely, they provide a time resolution better than 80 ps and an efficiency above 90% at a particle flux well in excess of 20 kHz/cm2 (up to 35–60 kHz/cm2), being at the core of a modular concept that is easily scalable. Recent measurements of the electrical and mechanical properties of this new material, together with its long-term behavior, are shortly summarized.