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In this work, we present a tandem ion mobility spectrometer (IMS) utilizing a highly efficient ion manipulator allowing to store, manipulate, and analyze ions under high electric field strengths and controlled ion-neutral reactions at ambient conditions. The arrangement of tandem drift regions and an ion manipulator in a single drift tube allows a sequence of mobility selection of precursor ions, followed by storage and analysis, mobility separation, and detection of the resulting product ions. In this article, we present a journey exploring the capabilities of the present instrument by a study of eight different primary alcohols characterized at reduced electric field strengths E/N of up to 120 Td with a water vapor concentration ranging from 40 to 540 ppb. Under these conditions, protonated alcohol monomers up to a carbon number of nine could be dissociated, resulting in 18 different fragmented product ions in total. The fragmentation patterns revealed regularities, which can be used for assignment to the chemical class and improved classification of unknown substances. Furthermore, both the time spent in high electrical field strengths and the reaction time with water vapor can be tuned precisely, allowing the fragment distribution to be influenced. Thus, further information regarding the relations of the product ions can be gathered in a standalone drift tube IMS for the first time.

A growing demand for low-cost gas sensors capable of detecting the smallest amounts of highly toxic substances in air, including chemical warfare agents (CWAs) and toxic industrial chemicals (TICs), has emerged in recent years. Ion mobility spectrometers (IMS) are particularly suitable for this application due to their high sensitivity and fast response times. In view of the preferred mobile use of such devices, miniaturized ion drift tubes are required as the core of IMS-based lightweight, low-cost, hand-held gas detectors. Thus, we evaluate the suitability of a miniaturized ion mobility spectrometer featuring an ion drift tube length of just 40 mm and a high resolving power of Rp= 60 for the detection of various CWAs, such as nerve agents sarin (GB), tabun (GA), soman (GD), and cyclosarin (GF), as well as the blister agent sulfur mustard (HD), the blood agent hydrogen cyanide (AC) and the choking agent chlorine (CL). We report on the limits of detection reaching minimum concentration levels of, for instance, 29 pptvfor sarin (GB) within an averaging time of only 1 s. Furthermore, we investigate the effects of precursors, simulants, and other common interfering substances on false positive alarms.

Dissertation, RWTH Aachen University, 2022; Aachen : RWTH Aachen University 1 Online-Ressource : Illustrationen, Diagramme (2022). = Dissertation, RWTH Aachen University, 2022, Gas filled detectors have been among the first detectors used with electronic read-out in particle physics. Among them, the Time Projection Chamber has proven to be exceptionally versatile. TPCs are deployed from ultra-low background experiments, like searches for neutrino-less double-beta decays, to ultra-high multiplicity events at nuclear colliders. The TPC operation principle has been applied to various gas mixtures at pressures well below andabove atmospheric pressures and even to liquefied gases. When placed inside a magnetic field, TPCs have the ability to identify charged particles by their track curvature and characteristic energy loss. The T2K long baseline neutrino experiment utilizes three TPCs as part of their near detector to identify particles produced by ν interactions and is anticipating an upgrade with two additional TPCs. After decreasing statistical uncertainties over the accumulated T2K lifetime of over 10 years, systematics stemming from poorly understood and measured low-energetic intra-nucleon interactions are among the dominant contributions to the total uncertainty. With the recently published T2K constraint of 3σ on the CP violating phase (δCP) in the lepton sector, the reduction of systematic uncertainties have become tantamount to the success of measuring δCP to 5σ precision. Two mega-projects are currently in the construction phase to challenge the 5σ boundary: Hyper Kamiokande, Super Kamoikande’s successor in Japan, and the Deep Underground Neutrino Observatory in the US. Both rely on a better understanding of the intra-nuclear processes involved in neutrino interactions to reach their sensitivity goal. Neutrino interactions on gas components, especially hydrogen, offer a promising prospect of filling gaps in the available data for developing and improving models. DUNE aims to construct a pressurized TPC at 10 bar that could deliver this data as part of the main neutrino-oscillation physics program. The used gas mixture will be predominantly argon to provide the constraining counter-part for the liquid argon TPCs of the far detector. A proposed later-stage mixture nominates an increased content of alkanes to introduce large amounts of free protons in the form of hydrogen for clean neutrino-nucleon interactions. A miniature TPC, capable of investigating the usability of the extremes of almost pure argon and pure alkanes is desirable as a proving ground for the search of a gas mixture for a full-scale TPC of >100 m³ as for DUNE’s near detector. The performance of a TPC requires precise knowledge of the swarm parameters of free electrons in gas at varying electrical fields, pressures and temperatures. One suitable kind of miniature TPC, called Gas Monitoring Chambers, was developed for T2K at RWTH Aachen University as a continuous calibration device. This work presents the construction of a High Pressure Gas Monitoring Chamber designed for measuring the drift velocity for gas studies and calibration of a full-scale TPC at up to 10 bar. The measurement curves of the gas mixtures P2, P10 and P50 as well as the pure gases CH4, C2H6 and C3H8 are compared to the state-of-the-art simulation program MagBoltz to verify readiness for simulations in the high pressure regime following ET/p scaling., Published by RWTH Aachen University, Aachen