NEXT Collaboration(Haefner, J. et al), Benlloch-Rodriguez, J. M., Carcel, S., Carrion, J. V., Martin-Albo, J., Martinez-Vara, M., et al. (2023). Reflectance and fluorescence characteristics of PTFE coated with TPB at visible, UV, and VUV as a function of thickness. J. Instrum., 18(3), P03016–21pp.
Abstract: Polytetrafluoroethylene (PTFE) is an excellent diffuse reflector widely used in light collection systems for particle physics experiments. In noble element systems, it is often coated with tetraphenyl butadiene (TPB) to allow detection of vacuum ultraviolet scintillation light. In this work this dependence is investigated for PTFE coated with TPB in air for light of wavelengths of 200 nm, 260 nm, and 450 nm. The results show that TPB-coated PTFE has a reflectance of approximately 92% for thicknesses ranging from 5 mm to 10 mm at 450 nm, with negligible variation as a function of thickness within this range. A cross-check of these results using an argon chamber supports the conclusion that the change in thickness from 5 mm to 10 mm does not affect significantly the light response at 128 nm. Our results indicate that pieces of TPB-coated PTFE thinner than the typical 10 mm can be used in particle physics detectors without compromising the light signal.
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Abele, H. et al, Algora, A., Gonzalez-Alonso, M., & Novella, P. (2023). Particle physics at the European Spallation Source. Phys. Rep., 1023, 1–84.
Abstract: Presently under construction in Lund, Sweden, the European Spallation Source (ESS) will be the world's brightest neutron source. As such, it has the potential for a particle physics program with a unique reach and which is complementary to that available at other facilities. This paper describes proposed particle physics activities for the ESS. These encompass the exploitation of both the neutrons and neutrinos produced at the ESS for high precision (sensitivity) measurements (searches).
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DUNE Collaboration(Abud, A. A. et al), Amedo, P., Antonova, M., Barenboim, G., Cervera-Villanueva, A., De Romeri, V., et al. (2023). Highly-parallelized simulation of a pixelated LArTPC on a GPU. J. Instrum., 18(4), P04034–35pp.
Abstract: The rapid development of general-purpose computing on graphics processing units (GPGPU) is allowing the implementation of highly-parallelized Monte Carlo simulation chains for particle physics experiments. This technique is particularly suitable for the simulation of a pixelated charge readout for time projection chambers, given the large number of channels that this technology employs. Here we present the first implementation of a full microphysical simulator of a liquid argon time projection chamber (LArTPC) equipped with light readout and pixelated charge readout, developed for the DUNE Near Detector. The software is implemented with an end-to-end set of GPU-optimized algorithms. The algorithms have been written in Python and translated into CUDA kernels using Numba, a just-in-time compiler for a subset of Python and NumPy instructions. The GPU implementation achieves a speed up of four orders of magnitude compared with the equivalent CPU version. The simulation of the current induced on 103 pixels takes around 1 ms on the GPU, compared with approximately 10 s on the CPU. The results of the simulation are compared against data from a pixel-readout LArTPC prototype.
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NEXT Collaboration(Navarro, K. E. et al), Carcel, S., Carrion, J. V., Lopez, F., Lopez-March, N., Martin-Albo, J., et al. (2023). A compact dication source for Ba2+ tagging and heavy metal ion sensor development. J. Instrum., 18(7), P07044–19pp.
Abstract: We present a tunable metal ion beam that delivers controllable ion currents in the picoamp range for testing of dry-phase ion sensors. Ion beams are formed by sequential atomic evaporation and single or multiple electron impact ionization, followed by acceleration into a sensing region. Controllability of the ionic charge state is achieved through tuning of electrode potentials that influence the retention time in the ionization region. Barium, lead, and cadmium samples have been used to test the system, with ion currents identified and quantified using a quadrupole mass analyzer. Realization of a clean Ba2+ ion beam within a bench-top system represents an important technical advance toward the development and characterization of barium tagging systems for neutrinoless double beta decay searches in xenon gas. This system also provides a testbed for investigation of novel ion sensing methodologies for environmental assay applications, with dication beams of Pb2+ and Cd2+ also demonstrated for this purpose.
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T2K Collaboration(Abe, K. et al), Antonova, M., Cervera-Villanueva, A., Molina Bueno, L., & Novella, P. (2023). Measurements of neutrino oscillation parameters from the T2K experiment using 3.6 x 10^21 protons on target. Eur. Phys. J. C, 83(9), 782–50pp.
Abstract: The T2K experiment presents new measurements of neutrino oscillation parameters using 19.7(16.3) x 10(20) protons on target (POT) in (anti-)neutrino mode at the far detector (FD). Compared to the previous analysis, an additional 4.7 x 10(20) POT neutrino data was collected at the FD. Significant improvements were made to the analysis methodology, with the near-detector analysis introducing new selections and using more than double the data. Additionally, this is the first T2K oscillation analysis to use NA61/SHINE data on a replica of the T2K target to tune the neutrino flux model, and the neutrino interaction model was improved to include new nuclear effects and calculations. Frequentist and Bayesian analyses are presented, including results on sin(2) theta(13) and the impact of priors on the delta(CP) measurement. Both analyses prefer the normal mass ordering and upper octant of sin(2) theta(23) with a nearly maximally CP-violating phase. Assuming the normal ordering and using the constraint on sin(2) theta(13) from reactors, sin(2) theta(23) = 0.561(-0.032)(+0.021) using Feldman-Cousins corrected intervals, and Delta m(32)(2) = 2.494(-0.058)(+0.041) x 10(-3) eV(2) using constant Delta chi(2) intervals. The CP-violating phase is constrained to delta(CP) = -1.97(-0.70)(+0.97) using Feldman-Cousins corrected intervals, and delta(CP) = 0, pi is excluded at more than 90% confidence level. A Jarlskog invariant of zero is excluded at more than 2 sigma credible level using a flat prior in delta(CP), and just below 2 sigma using a flat prior in sin delta(CP). When the external constraint on sin(2) nu(13) is removed, sin(2) theta(13) = 28.0(-6.5)(+2.8) x 10(-3), in agreement with measurements from reactor experiments. These results are consistent with previous T2K analyses.
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