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Register a new userLab::Measurement - A portable and extensible framework for controlling lab equipment and conducting measurements
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Added by
Andreas K. H\\\"uttel
Publication date
2018
fields
Physics
and research's language is
English
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Lab::Measurement is a framework for test and measurement automatization using Perl 5. While primarily developed with applications in mesoscopic physics in mind, it is widely adaptable. Internally, a layer model is implemented. Communication protocols such as IEEE 488, USB Test & Measurement, or, e.g., VXI-11 are addressed by the connection layer. The wide range of supported connection backends enables unique cross-platform portability. At the instrument layer, objects correspond to equipment connected to the measurement PC (e.g., voltage sources, magnet power supplies, multimeters, etc.). The high-level sweep layer automates the creation of measurement loops, with simultaneous plotting and data logging. An extensive unit testing framework is used to verify functionality even without connected equipment. Lab::Measurement is distributed as free and open source software.
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Linear alkylbenzene has been recently used as the solvent of liquid scintillator by several neutrino experiments. The energy quenching effect of a linear alkylbenzene based liquid scintillator is studied in this paper with a 14 MeV D-T compact neutron generator, to improve the energy non-linearity modelling of this kind of detectors. The recoiled proton in the liquid scintillator has a kinetic energy ranging from 0.5 MeV to 13 MeV. The data is used to extract the parameters of the Birks law, an empirical model to describe the energy quenching effect of the liquid scintillator.
We describe a dynamically polarized target that has been utilized for two electron scattering experiments in Hall A at Jefferson Lab. The primary components of the target are a new, high cooling power 4He evaporation refrigerator, and a re-purposed, superconducting split-coil magnet. It has been used to polarize protons in irradiated NH3 at a temperature of 1 K and at fields of 2.5 and 5.0 Tesla. The performance of the target material in the electron beam under these conditions will be discussed. Maximum polarizations of 28% and 95% were obtained at those fields, respectively. To satisfy the requirements of both experiments, the magnet had to be routinely rotated between angles of 0, 6, and 90 degrees with respect to the incident electron beam. This was accomplished using a new rotating vacuum seal which permits rotations to be performed in only a few minutes.
Electron antineutrinos are detected in organic liquid scintillator based neutrino experiments by means of the inverse beta decay, producing both a positron and a neutron. The positron may form a bound state together with an electron, called positronium (Ps). The longer-lived spin state of Ps, orthopositronium (o-Ps) has a lifetime of about $3,mathrm{ns}$ in organic liquid scintillators (LS). Its formation changes the time distribution of photon emission, which affects positron reconstruction algorithms and allows the application of pulse shape discrimination (PSD) to distinguish electron from positron events. In this work, we measured the lifetime $tau_2$ of o-Ps in the linear alkylbenzene (LAB) based LS of the JUNO (Jiangmen Underground Neutrino Observatory) experiment including wavelength shifters, obtaining $tau_2 = 2.97,mathrm{ns} pm 0.04,mathrm{ns}$. Due to systematics, which are not yet completely understood, we are not able to give a final result for the o-Ps formation probability $I_2$. We use a novel type of setup, which allows a better background suppression as compared to commonly used PALS (positron annihilation lifetime spectroscopy) measurements.
This document describes the technical design concept of a compact high intensity, multi-GeV photon source. Capable of producing 10^12 equivalent photons per second this novel device will provide unprecedented access to physics processes with very small scattering probabilities such as hard exclusive reactions on the nucleon. When combined with dynamic nuclear polarized targets, its deployment will result in a large gain in polarized experiment figure-of-merit compared to all previous measurements. Compared to a traditional bremsstrahlung photon source the proposed concept presents several advantages, most significantly in providing a full intensity in a small spot at the target and in taking advantage of the narrow angular spread associated with high energy bremsstrahlung compare to the wide angular distribution of the secondary radiation to minimize the operational prompt and activation radiation dose rates.
The $alpha$-particle light response of liquid scintillators based on linear alkylbenzene (LAB) has been measured with three different experimental approaches. In the first approach, $alpha$-particles were produced in the scintillator via $^{12}$C($n$,$alpha$)$^9$Be reactions. In the second approach, the scintillator was loaded with 2% of $^{mathrm{nat}}$Sm providing an $alpha$-emitter, $^{147}$Sm, as an internal source. In the third approach, a scintillator flask was deployed into the water-filled SNO+ detector and the radioactive contaminants $^{222}$Rn, $^{218}$Po and $^{214}$Po provided the $alpha$-particle signal. The behavior of the observed $alpha$-particle light outputs are in agreement with each case successfully described by Birks law. The resulting Birks parameter $kB$ ranges from $(0.0066pm0.0016)$ cm/MeV to $(0.0076pm0.0003)$ cm/MeV. In the first approach, the $alpha$-particle light response was measured simultaneously with the light response of recoil protons produced via neutron-proton elastic scattering. This enabled a first time a direct comparison of $kB$ describing the proton and the $alpha$-particle response of LAB based scintillator. The observed $kB$ values describing the two light response functions deviate by more than $5sigma$. The presented results are valuable for all current and future detectors, using LAB based scintillator as target, since they depend on an accurate knowledge of the scintillator response to different particles.
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