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Menendez, A., Esperante, D., Garcia-Olcina, R., Torres, J., Perez-Soler, J., Marco, R., et al. (2022). RF Acquisition System Based on μTCA for Testing of High-Gradient Acceleration Cavities. Electronics, 11(5), 720–22pp.
Abstract: The radio frequency (RF) laboratory hosted in the Corpuscular Physics Institute (IFIC) of the University of Valencia is designed to house a high-power and high-repetition-rate facility to test normal conduction RF accelerator cavities in the S-Band (2.9985 GHz) in order to perform R & D activities related to particle accelerator cavities. The system, which manages the entire process of RF signal generation, data acquisition and closed-loop control of the laboratory, is currently based on a modular and compact PXI platform system. This contribution details the development of a platform with similar features, but which is based on open architecture standards at both the hardware and software level. For this purpose, a complete system based on the μTCA platform has been developed. This new system must be able to work with accelerator cavities at other operating frequencies, such as 750 MHz, as well as to explore different options at firmware and software levels based on open-source codes.
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Mendoza, E., Alcayne, V., Cano-Ott, D., Gonzalez-Romero, E., Martinez, T., de Rada, A. P., et al. (2023). Neutron capture measurements with high efficiency detectors and the Pulse Height Weighting Technique. Nucl. Instrum. Methods Phys. Res. A, 1047, 167894–16pp.
Abstract: Neutron capture cross section measurements in time-of-flight facilities are usually performed by detecting the prompt 7-rays emitted in the capture reactions. One of the difficulties to be addressed in these measurements is that the emitted 7-rays may change with the neutron energy, and therefore also the detection efficiency. To deal with this situation, many measurements use the so called Total Energy Detection (TED) technique, usually in combination with the Pulse Height Weighting Technique (PHWT). With it, it is sought that the detection efficiency depends only on the total energy of the 7-ray cascade, which does not vary much with the neutron energy. This technique was developed in the 1960s and has been used in many neutron capture experiments to date. One of the requirements of the technique is that 7-ray detectors have a low efficiency. This has meant that the PHWT has been used with experimental setups with low detection efficiencies. However, this condition does not have to be fulfilled by the experimental system as a whole. The main goal of this work is to show that it is possible to measure with a high efficiency detection system that uses the PHWT, and how to analyze the measured data.
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Mena, O., Palomares-Ruiz, S., Villanueva-Domingo, P., & Witte, S. J. (2019). Constraining the primordial black hole abundance with 21-cm cosmology. Phys. Rev. D, 100(4), 043540–23pp.
Abstract: The discoveries of a number of binary black hole mergers by LIGO and VIRGO have reinvigorated the interest that primordial black holes (PBHs) of tens of solar masses could contribute non-negligibly to the dark matter energy density. Should even a small population of PBHs with masses greater than or similar to O(M-circle dot) exist, they could profoundly impact the properties of the intergalactic medium and provide insight into novel processes at work in the early Universe. We demonstrate here that observations of the 21-cm transition in neutral hydrogen during the epochs of reionization and cosmic dawn will likely provide one of the most stringent tests of solar mass PBHs. In the context of 21-cm cosmology, PBHs give rise to three distinct observable effects: (i) the modification to the primordial power spectrum (and thus also the halo mass function) induced by Poisson noise, (ii) a uniform heating and ionization of the intergalactic medium via x-rays produced during accretion, and (iii) a local modification to the temperature and density of the ambient medium surrounding isolated PBHs. Using a four-parameter astrophysical model, we show that experiments like SKA and HERA could potentially improve upon existing constraints derived using observations of the cosmic microwave background by more than 1 order of magnitude.
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NEXT Collaboration(McDonald, A. D. et al), Alvarez, V., Benlloch-Rodriguez, J. M., Carcel, S., Carrion, J. V., Diaz, J., et al. (2019). Electron drift and longitudinal diffusion in high pressure xenon-helium gas mixtures. J. Instrum., 14, P08009–19pp.
Abstract: We report new measurements of the drift velocity and longitudinal diffusion coefficients of electrons in pure xenon gas and in xenon-helium gas mixtures at 1-9 bar and electric field strengths of 50-300 V/cm. In pure xenon we find excellent agreement with world data at all E/P, for both drift velocity and diffusion coefficients. However, a larger value of the longitudinal diffusion coefficient than theoretical predictions is found at low E/P in pure xenon, below the range of reduced fields usually probed by TPC experiments. A similar effect is observed in xenon-helium gas mixtures at somewhat larger E/P. Drift velocities in xenon-helium mixtures are found to be theoretically well predicted. Although longitudinal diffusion in xenon-helium mixtures is found to be larger than anticipated, extrapolation based on the measured longitudinal diffusion coefficients suggest that the use of helium additives to reduce transverse diffusion in xenon gas remains a promising prospect.
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McDermott, S. D., & Witte, S. J. (2020). Cosmological evolution of light dark photon dark matter. Phys. Rev. D, 101(6), 063030–14pp.
Abstract: Light dark photons are subject to various plasma effects, such as Debye screening and resonant oscillations, which can lead to a more complex cosmological evolution than is experienced by conventional cold dark matter candidates. Maintaining a consistent history of dark photon dark matter requires ensuring that the superthennal abundance present in the early Universe (i) does not deviate significantly after the formation of the cosmic microwave background (CMB), and (ii) does not excessively leak into the Standard Model plasma after big band nucleosynthesis (BBN). We point out that the role of nonresonant absorption, which has previously been neglected in cosmological studies of this dark matter candidate, produces strong constraints on dark photon dark matter with mass as low as 10(-22) eV. Furthermore, we show that resonant conversion of dark photons after recombination can produce excessive heating of the intergalactic medium (IGM) which is capable of prematurely reionizing hydrogen and helium, leaving a distinct imprint on both the Ly-a forest and the integrated optical depth of the CMB. Our constraints surpass existing cosmological bounds by more than 5 orders of magnitude across a wide range of dark photon masses.
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n_TOF Collaboration(Mazzone, A. et al), Babiano-Suarez, V., Caballero, L., Domingo-Pardo, C., Ladarescu, I., & Tain, J. L. (2020). Measurement of the Gd-154(n, gamma) cross section and its astrophysical implications. Phys. Lett. B, 804, 135405–6pp.
Abstract: The neutron capture cross section of Gd-154 was measured from 1 eV to 300 keV in the experimental area located 185 m from the CERN n_TOF neutron spallation source, using a metallic sample of gadolinium, enriched to 67% in Gd-154. The capture measurement, performed with four C6D6 scintillation detectors, has been complemented by a transmission measurement performed at the GELINA time-of-flight facility (JRC-Geel), thus minimising the uncertainty related to sample composition. An accurate Maxwellian averaged capture cross section (MACS) was deduced over the temperature range of interest for s process nucleosynthesis modelling. We report a value of 880(50) mb for the MACS at kT = 30 keV, significantly lower compared to values available in literature. The new adopted Gd-154(n, gamma) cross section reduces the discrepancy between observed and calculated solar s-only isotopic abundances predicted by s-process nucleosynthesis models.
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Mavromatos, N. E., & Mitsou, V. A. (2020). Magnetic monopoles revisited: Models and searches at colliders and in the Cosmos. Int. J. Mod. Phys. A, 35(23), 2030012–81pp.
Abstract: In this review, we discuss recent developments in both the theory and the experimental searches of magnetic monopoles in past, current and future colliders and in the Cosmos. The theoretical models include, apart from the standard Grand Unified Theories, extensions of the Standard Model that admit magnetic monopole solutions with finite energy and masses that can be as light as a few TeV. Specifically, we discuss, among other scenarios, modified Cho-Maison monopoles and magnetic monopoles in (string-inspired, higher derivative) Born-Infeld extensions of the hypercharge sector of the Standard Model. We also outline the conditions for which effective field theories describing the interaction of monopoles with photons are valid and can be used for result interpretation in monopole production at colliders. The experimental part of the review focuses on, past and present, cosmic and collider searches, including the latest bounds on monopole masses and magnetic charges by the ATLAS and MoEDAL experiments at the LHC, as well as prospects for future searches.
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Masud, M., Bishai, M., & Mehta, P. (2019). Extricating New Physics Scenarios at DUNE with Higher Energy Beams. Sci Rep, 9, 352–9pp.
Abstract: The proposed Deep Underground Neutrino Experiment (DUNE) utilizes a wide-band on-axis tunable muon-(anti) neutrino beam with a baseline of 1300 km to search for CP violation with high precision. Given the long baseline, DUNE is also sensitive to effects due to matter induced non-standard neutrino interactions (NSI) which can interfere with the standard three-flavor oscillation paradigm. Hence it is desirable to design strategies to disentangle effects due to NSI from standard oscillations. In this article, we exploit the tunability of the DUNE neutrino beam over a wide-range of energies to devise an experimental strategy for separating oscillation effects due to NSI from the standard three-flavor oscillation scenario. Using chi(2) analysis, we obtain an optimal combination of beam tunes and distribution of run times in neutrino and anti-neutrino modes that would enable DUNE to isolate new physics scenarios from the standard. We can distinguish scenarios at 3 sigma (5 sigma) level for almost all (similar to 50%) values of delta. To the best of our knowledge, our strategy is entirely new and has not been reported elsewhere.
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Masud, M., Roy, S., & Mehta, P. (2019). Correlations and degeneracies among the NSI parameters with tunable beams at DUNE. Phys. Rev. D, 99(11), 115032–19pp.
Abstract: The Deep Underground Neutrino Experiment (DUNE) is a leading experiment in neutrino physics which is presently under construction. DUNE aims to measure the yet unknown parameters in the three flavor oscillation scenario which includes discovery of leptonic CP violation, determination of the mass hierarchy and determination of the octant of theta(23). Additionally, the ancillary goals of DUNE include probing the subdominant effects induced by new physics. A widely studied new physics scenario is that of nonstandard neutrino interactions (NSI) in propagation which impacts the oscillations of neutrinos. We consider some of the essential NSI parameters impacting the oscillation signals at DUNE and explore the space of NSI parameters as well as study their correlations among themselves and with the yet unknown CP violating phase, delta appearing in the standard paradigm. The experiment utilizes a wide band beam and provides us with a unique opportunity to utilize different beam tunes at DUNE. We demonstrate that combining information from different beam tunes (low energy and medium energy) available at DUNE impacts the ability to probe some of these parameters and leads to altering the allowed regions in two-dimensional space of parameters considered.
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Masud, M., Mehta, P., Ternes, C. A., & Tortola, M. (2021). Non-standard neutrino oscillations: perspective from unitarity triangles. J. High Energy Phys., 05(5), 171–19pp.
Abstract: We formulate an alternative approach based on unitarity triangles to describe neutrino oscillations in presence of non-standard interactions (NSI). Using perturbation theory, we derive the expression for the oscillation probability in case of NSI and cast it in terms of the three independent parameters of the leptonic unitarity triangle (LUT). The form invariance of the probability expression (even in presence of new physics scenario as long as the mixing matrix is unitary) facilitates a neat geometric view of neutrino oscillations in terms of LUT. We examine the regime of validity of perturbative expansions in the NSI case and make comparisons with approximate expressions existing in literature. We uncover some interesting dependencies on NSI terms while studying the evolution of LUT parameters and the Jarlskog invariant. Interestingly, the geometric approach based on LUT allows us to express the oscillation probabilities for a given pair of neutrino flavours in terms of only three (and not four) degrees of freedom which are related to the geometric properties (sides and angles) of the triangle. Moreover, the LUT parameters are invariant under rephasing transformations and independent of the parameterization adopted.
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