Blinding for precision scattering experiments: The MUSE approach as a case study

Human bias is capable of changing the analysis of measured data sufficiently to alter the results of an experiment. It is incumbent upon modern experiments, especially those investigating quantities considered contentious in the broader community, to blind their analysis in an effort to minimize bias. The choice of a blinding model is experiment specific, but should also aim to prevent accidental release of results before an analysis is finalized. In this paper, we discuss common threats to an unbiased analysis, as well as common quantities that can be blinded in different types of nuclear physics experiments. We use the Muon Scattering Experiment as an example, and detail the blinding scheme used therein.Comment: 6 pages, 3 figure

The Two-Photon Exchange Experiment at DESY

We propose a new measurement of the ratio of positron-proton to electron-proton elastic scattering at DESY. The purpose is to determine the contributions beyond single-photon exchange, which are essential for the Quantum Electrodynamic (QED) description of the most fundamental process in hadronic physics. By utilizing a 20 cm long liquid hydrogen target in conjunction with the extracted beam from the DESY synchrotron, we can achieve an average luminosity of $2.12\times10^{35}$ cm$^{-2}\cdot$s$^{-1}\cdot$sr$^{-1}$ ($\approx200$ times the luminosity achieved by OLYMPUS). The proposed TPEX experiment entails a commissioning run at 2 GeV, followed by measurements at 3 GeV, thereby providing new data up to $Q^2=4.6$ (GeV/$c$)$^2$ (twice the range of current measurements). We present and discuss the proposed experimental setup, run plan, and expectations.Comment: 10 pages, 14 figures. arXiv admin note: substantial text overlap with arXiv:2301.0470

Timing detectors with SiPM read-out for the MUSE experiment at PSI

The Muon Scattering Experiment at the Paul Scherrer Institute uses a mixed beam of electrons, muons, and pions, necessitating precise timing to identify the beam particles and reactions they cause. We describe the design and performance of three timing detectors using plastic scintillator read out with silicon photomultipliers that have been built for the experiment. The Beam Hodoscope, upstream of the scattering target, counts the beam flux and precisely times beam particles both to identify species and provide a starting time for time-of-flight measurements. The Beam Monitor, downstream of the scattering target, counts the unscattered beam flux, helps identify background in scattering events, and precisely times beam particles for time-of-flight measurements. The Beam Focus Monitor, mounted on the target ladder under the liquid hydrogen target inside the target vacuum chamber, is used in dedicated runs to sample the beam spot at three points near the target center, where the beam should be focused

Evaluation of fruit raw materials chemical composition by the content of organic acids and macronutrients

The actual content of organic acids and macronutrients in the samples of purees made of strawberries, black currants, blackberries, cranberries, pears, cherries, apricots was determined in the work. The average value of malic acid mass fraction in the studied types of raw materials was 0.7%, while in apple puree it counted 0.43%. The average value of the sum of potassium and magnesium mass fraction for the presented types of raw materials was 212 mg / 100 g, and the previously determined value for apple puree was 211 mg / 100 g. Comparison of the actual values and reference data of the ranges of malic acid content and potassium and magnesium sum shows the possibility of the fruit component content determination in various confectionery products groups. Organic acids and macronutrients were proven to be used as identification indicators for many groups of fruit raw materials. The factual data on organic acids and macronutrients content in some types of fruit purees made of tropical fruits, which are characterized by very wide ranges, were obtained in the work. The mass fraction of malic acid in the studied samples is in the range from 0.03% to 0.30%. The potassium content ranges from 60 mg to 301 mg per 100 g of product, and the magnesium content ranges from 6 mg to 21 mg per 100 g of product. The preservation of organic acids and macronutrients in apple puree was proved during storage. This indicates the possibility of their use in the confectionery industry as accurate and reliable criteria for fruit raw materials identification in finished products

Limit characteristics of switches based on planar open discharge

The limit characteristics of switches based on open discharge (OD) with counter-propagating electron beams were studied. Such switches (kivotrons) are able to generate high-voltage pulses with a sub-nanosecond leading edge. Separately obtained limit values of the switch parameters are as follows: current density up to 1000 A cm−2, operating voltage up to 100 kV, switching time down to 100 ps, the degree of pulse compression up to 100, a pulse repetition frequency up to 100 kHz (in burst mode), and an efficiency of more than 0.9. It was shown that the fast current development arises when the discharge self-sustaining mode is caused by the photoemission from the cathodes due to the resonant radiation emitted by fast helium atoms that have a large Doppler shift with respect to the line center. As a result, the emitted radiation reaches the cathodes without absorption by the helium gas. The presence of a fast atom group with an energy determined by the applied voltage was experimentally demonstrated. The dynamics of the plasma decay was studied. It is shown that the radiative, collisional-radiative, and three-body collision recombination mechanisms significantly contribute to the afterglow decay only when the plasma density remains higher than 1012 cm−3. The main mechanism of the further plasma decay is the diffusion of plasma particles onto the wall. Therefore, the effect of recombination in the plasma bulk is observed only during the first 10–20 μs of the afterglow. The results of the lasing characteristics of a copper vapor laser excited by pulses generated by an OD-based switch are presented