The JUNO experiment Top Tracker

Journal of Instrumentation

The complexity of modern cosmic ray observatories and the rich data sets they capture often require a sophisticated software framework to support the simulation of physical processes, detector response, as well as reconstruction and analysis of real and simulated data. Here we present the EUSO-Offline framework. The code base was originally developed by the Pierre Auger Collaboration, and portions of it have been adopted by other collaborations to suit their needs. We have extended this software to fulfill the requirements of Ultra-High Energy Cosmic Ray detectors and very high energy neutrino detectors developed for the Joint Exploratory Missions for an Extreme Universe Observatory (JEM-EUSO). These path-finder instruments constitute a program to chart the path to a future space-based mission like POEMMA. For completeness, we describe the overall structure of the framework developed by the Auger …

arXiv preprint arXiv:2402.05383

Daya Bay presents the first measurement of cosmogenic He isotope production in liquid scintillator, using an innovative method for identifying cascade decays of He and its child isotope, Li. We also measure the production yield of Li isotopes using well-established methodology. The results, in units of 10gcm, are 0.3070.042, 0.3410.040, and 0.5460.076 for He, and 6.730.73, 6.750.70, and 13.740.82 for Li at average muon energies of 63.9~GeV, 64.7~GeV, and 143.0~GeV, respectively. The measured production rate of He isotopes is more than an order of magnitude lower than any other measurement of cosmogenic isotope production. It replaces the results of previous attempts to determine the ratio of He to Li production that yielded a wide range of limits from 0 to 30\%. The results provide future liquid-scintillator-based experiments with improved ability to predict cosmogenic backgrounds.

Journal of High Energy Physics

The polarization of τ leptons is measured using leptonic and hadronic τ lepton decays in Z→ τ+ τ− events in proton-proton collisions at= 13 TeV recorded by CMS at the CERN LHC with an integrated luminosity of 36.3 fb− 1. The measured τ− lepton polarization at the Z boson mass pole is=− 0.144±0.006 (stat)±0.014 (syst)=− 0.144±0.015, in good agreement with the measurement of the τ lepton asymmetry parameter of A τ= 0.1439±0.0043= at LEP. The τ lepton polarization depends on the ratio of the vector to axial-vector couplings of the τ leptons in the neutral current expression, and thus on the effective weak mixing angle sin 2, independently of the Z boson production mechanism. The obtained value sin 2= 0.2319±0. 0008 (stat)±0. 0018 (syst)= 0. 2319±0. 0019 is in good agreement with measurements at e+ e− colliders.

Computing and Software for Big Science

The need for large-scale production of highly accurate simulated event samples for the extensive physics programme of the ATLAS experiment at the Large Hadron Collider motivates the development of new simulation techniques. Building on the recent success of deep learning algorithms, variational autoencoders and generative adversarial networks are investigated for modelling the response of the central region of the ATLAS electromagnetic calorimeter to photons of various energies. The properties of synthesised showers are compared with showers from a full detector simulation using geant4. Both variational autoencoders and generative adversarial networks are capable of quickly simulating electromagnetic showers with correct total energies and stochasticity, though the modelling of some shower shape distributions requires more refinement. This feasibility study demonstrates the potential of using such algorithms for ATLAS fast calorimeter simulation in the future and shows a possible way to complement current simulation techniques.

The\Xbsd decay topology, where the\Xb baryon decays to\psiXim with $\PGy\to\mumu $(upper) or\jpsiLaKm (lower), where\PGy refers to the\jpsi and\psit mesons. The distances given are the average decay lengths, .The\Xbsd decay topology, where the\Xb baryon decays to\psiXim with $\PGy\to\mumu $(upper) or\jpsiLaKm (lower), where\PGy refers to the\jpsi and\psit mesons. The distances given are the average decay lengths, .

Journal of High Energy Physics

A measurement of the Higgs boson (H) production via vector boson fusion (VBF) and its decay into a bottom quark-antiquark pair () is presented using proton-proton collision data recorded by the CMS experiment at= 13 TeV and corresponding to an integrated luminosity of 90.8 fb− 1. Treating the gluon-gluon fusion process as a background and constraining its rate to the value expected in the standard model (SM) within uncertainties, the signal strength of the VBF process, defined as the ratio of the observed signal rate to that predicted by the SM, is measured to be. The VBF signal is observed with a significance of 2.4 standard deviations relative to the background prediction, while the expected significance is 2.7 standard deviations. Considering inclusive Higgs boson production and decay into bottom quarks, the signal strength is measured to be, corresponding to an observed …

A search for the production of long-lived particles in proton-proton collisions at a center-of-mass energy of 13 TeV at the CERN LHC is presented. The search is based on data collected by the CMS experiment in 2016-2018, corresponding to a total integrated luminosity of 137 fb. This search is designed to be sensitive to long-lived particles with mean proper decay lengths between 0.1 and 1000 m, whose decay products produce a final state with at least one displaced vertex and missing transverse momentum. A machine learning algorithm, which improves the background rejection power by more than an order of magnitude, is applied to improve the sensitivity. The observation is consistent with the standard model background prediction, and the results are used to constrain split supersymmetry (SUSY) and gauge-mediated SUSY breaking models with different gluino mean proper decay lengths and masses. This search is the first CMS search that shows sensitivity to hadronically decaying long-lived particles from signals with mass differences between the gluino and neutralino below 100 GeV. It sets the most stringent limits to date for split-SUSY models and gauge-mediated SUSY breaking models with gluino proper decay length less than 6 m.

This paper presents the measurement of fiducial and differential cross sections for both the inclusive and electroweak production of a same-sign W-boson pair in association with two jets (W±W±jj) using 139 fb− 1 of proton-proton collision data recorded at a centre-of-mass energy of s = 13 TeV by the ATLAS detector at the Large Hadron Collider. The analysis is performed by selecting two same-charge leptons, electron or muon, and at least two jets with large invariant mass and a large rapidity difference. The measured fiducial cross sections for electroweak and inclusive W±W±jj production are 2.92±0.22 (stat.)±0.19 (syst.) fb and 3.38±0.22 (stat.)±0.19 (syst.) fb, respectively, in agreement with Standard Model predictions. The measurements are used to constrain anomalous quartic gauge couplings by extracting 95% confidence level intervals on dimension-8 operators. A search for doubly charged Higgs bosons H±±that are produced in vector-boson fusion processes and decay into a same-sign W boson pair is performed. The largest deviation from the Standard Model occurs for an H±±mass near 450 GeV, with a global significance of 2.5 standard deviations.

A combination of the results of several searches for the electroweak production of the supersymmetric partners of standard model bosons, and of charged leptons, is presented. All searches use proton-proton collision data at = 13 TeV recorded with the CMS detector at the LHC in 2016-2018. The analyzed data correspond to an integrated luminosity of up to 137 fb. The results are interpreted in terms of simplified models of supersymmetry. Two new interpretations are added with this combination: a model spectrum with the bino as the lightest supersymmetric particle together with mass-degenerate higgsinos decaying to the bino and a standard model boson, and the compressed-spectrum region of a previously studied model of slepton pair production. Improved analysis techniques are employed to optimize sensitivity for the compressed spectra in the wino and slepton pair production models. The results are consistent with expectations from the standard model. The combination provides a more comprehensive coverage of the model parameter space than the individual searches, extending the exclusion by up to 125 GeV, and also targets some of the intermediate gaps in the mass coverage.

arXiv preprint arXiv:2401.08252

Using events collected with the BESIII detector at BEPCII, the decay of is observed for the first time. The branching fraction of this decay is measured to be $\mathcal{B}_{\psi(3686) \to \Omega^- K^+ \bar{\Xi}^0 +c.c.}=(2.78 \pm 0.40 \pm 0.18 ) \times 10^{-6}$, where the first uncertainty is statistical and the second is systematic. Possible baryon excited states are searched for in this decay, but no evident intermediate state is observed with the current sample size.

Very recently, the Large High Altitude Air Shower Observatory (LHAASO) reported the observation of the very early TeV afterglow of the brightest-of-all-time GRB 221009A, recording the highest photon statistics in the TeV band ever from a gamma-ray burst. We use this unique observation to place stringent constraints on an energy dependence of the speed of light in vacuum, a manifestation of Lorentz invariance violation (LIV) predicted by some quantum gravity (QG) theories. Our results show that the 95% confidence level lower limits on the QG energy scales are times of the Planck energy for the linear, and for the quadratic LIV effects, respectively. Our limits on the quadratic LIV case improve previous best bounds by factors of 5--7.

A search for beyond the standard model spin-0 bosons, , that decay into pairs of electrons, muons, or tau leptons is presented. The search targets the associated production of such bosons with a W or Z gauge boson, or a top quark-antiquark pair, and uses events with three or four charged leptons, including hadronically decaying tau leptons. The proton-proton collision data set used in the analysis was collected at the LHC from 2016 to 2018 at a center-of-mass energy of 13 TeV, and corresponds to an integrated luminosity of 138 fb. The observations are consistent with the predictions from standard model processes. Upper limits are placed on the product of cross sections and branching fractions of such new particles over the mass range of 15 to 350 GeV with scalar, pseudoscalar, or Higgs-boson-like couplings, as well as on the product of coupling parameters and branching fractions. Several model-dependent exclusion limits are also presented. For a Higgs-boson-like model, limits are set on the mixing angle of the Higgs boson with the boson. For the associated production of a boson with a top quark-antiquark pair, limits are set on the coupling to top quarks. Finally, limits are set for the first time on a fermiophilic dilaton-like model with scalar couplings and a fermiophilic axion-like model with pseudoscalar couplings.

Optica

The wind mission Aeolus of the European Space Agency was a groundbreaking achievement for Earth observation. Between 2018 and 2023, the space-borne lidar instrument ALADIN onboard the Aeolus satellite measured atmospheric wind profiles with global coverage, which contributed to improving the accuracy of numerical weather prediction. The precision of the wind observations, however, declined over the course of the mission due to a progressive loss of the atmospheric backscatter signal. The analysis of the root cause was supported by the Pierre Auger Observatory in Argentina whose fluorescence detector registered the ultraviolet laser pulses emitted from the instrument in space, thereby offering an estimation of the laser energy at the exit of the instrument for several days in 2019, 2020, and 2021. The reconstruction of the laser beam not only allowed for an independent assessment of the Aeolus …

arXiv preprint arXiv:2401.14720

We present measurements of the Born cross sections for the processes and at center-of-mass energies from 4.308 to 4.951 GeV. The measurements are performed with data samples corresponding to an integrated luminosity of 11.0 collected with the BESIII detector operating at the BEPCII storage ring. Assuming the signals come from a single resonance, the mass and width are determined to be MeV/ and MeV, respectively, which is consistent with the parameters of the well-established resonance . In addition, we also use one single resonance to describe the line shape, and determine the mass and width to be MeV/ and MeV, respectively. The structure of this line shape requires further understanding.

arXiv preprint arXiv:2404.07436

The Born cross sections for the process are measured at 22 center-of-mass energies from 2.000 to 3.080 GeV using data collected with the BESIII detector at the BEPCII collider. A resonant structure is observed with a statistical significance of 9.6. A Breit-Wigner fit determines its mass to be and its width to be , where the first uncertainties are statistical and the second are systematic.

JUNO-TAO design, prototype and its impact for JUNO physics - NASA/ADS Now on home page ads icon ads Enable full ADS view NASA/ADS JUNO-TAO design, prototype and its impact for JUNO physics Lombardo, C. ; JUNO Collaboration Abstract Publication: The European Physical Society Conference on High Energy Physics Pub Date: March 2024 Bibcode: 2024epsc.confE.192L full text sources Publisher | © The SAO/NASA Astrophysics Data System adshelp[at]cfa.harvard.edu The ADS is operated by the Smithsonian Astrophysical Observatory under NASA Cooperative Agreement NNX16AC86A NASA logo Smithsonian logo Resources About ADS ADS Help What's New Careers@ADS Social @adsabs ADS Blog Project Switch to full ADS Is ADS down? (or is it just me...) Smithsonian Institution Smithsonian Privacy Notice Smithsonian Terms of Use Smithsonian Astrophysical Observatory NASA …

arXiv preprint arXiv:2404.03217

Based on events collected by the BESIII collaboration, evidence of the hadronic decay is found with a significance of in the process. The branching fraction of is measured to be , where the first and second uncertainties are statistical and systematic, respectively. Combining with the exclusive decay width of , our result indicates inconsistencies with both pQCD and NRQCD predictions.

arXiv preprint arXiv:2404.04917

We search for the hadronic decay in the radiative decay using events collected by the BESIII detector at the BEPCII collider. No significant signal is found, and the upper limit of is determined to be at the 90\% confidence level. Using transitions, we also measure the branching fractions of , which are $\mathcal{B}[\chi_{c0}\to 2(\pi^+\pi^-)]=(2.127\pm 0.002~(\mathrm{stat.})\pm 0.101~(\mathrm{syst.}))$\%, $\mathcal{B}[\chi_{c1}\to 2(\pi^+\pi^-)]=(0.685\pm 0.001~(\mathrm{stat.})\pm 0.031~\mathrm{syst.}))$\%, and $\mathcal{B}[\chi_{c2}\to 2(\pi^+\pi^-)]=(1.153\pm 0.001~(\mathrm{stat.})\pm 0.063~(\mathrm{syst.}))$\%.

Physical Review D

The process e+ e−→ Σ+ Σ− is studied from threshold up to 3.04 GeV/c 2 via the initial-state radiation technique using data with an integrated luminosity of 12.0 fb− 1, collected at center-of-mass energies between 3.773 and 4.258 GeV with the BESIII detector at the BEPCII collider. The pair production cross sections and the effective form factors of Σ are measured in eleven Σ+ Σ− invariant mass intervals from threshold to 3.04 GeV/c 2. The results are consistent with the previous results from Belle and BESIII. Furthermore, the branching fractions of the decays J/ψ→ Σ+ Σ− and ψ (3686)→ Σ+ Σ− are determined and the obtained results are consistent with the previous results of BESIII.

arXiv preprint arXiv:2401.02901

The full data set of the Daya Bay reactor neutrino experiment is used to probe the effect of the charged current non-standard interactions (CC-NSI) on neutrino oscillation experiments. Two different approaches are applied and constraints on the corresponding CC-NSI parameters are obtained with the neutrino flux taken from the Huber-Mueller model with a uncertainty. Both approaches are performed with the analytical expressions of the effective survival probability valid up to all orders in the CC-NSI parameters. For the quantum mechanics-based approach (QM-NSI), the constraints on the CC-NSI parameters and are extracted with and without the assumption that the effects of the new physics are the same in the production and detection processes, respectively. The approach based on the effective field theory (EFT-NSI) deals with four types of CC-NSI represented by the parameters . For both approaches, the results for the CC-NSI parameters are shown for cases with various fixed values of the CC-NSI and the Dirac CP-violating phases, and when they are allowed to vary freely. We find that constraints on the QM-NSI parameters and from the Daya Bay experiment alone can reach the order for the former and for the latter, while for EFT-NSI parameters , we obtain for both cases.

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment

This work presents a systematic study of the properties (Light Output Non-Uniformity (LONU) and energy resolution) of two CsI (Tl) scintillation units over a span of almost three years, under adverse conditions of humidity and temperature. These two crystals are part of the CALIFA detector, a highly segmented calorimeter and spectrometer for γ rays and light-charged particles, that is placed surrounding the reaction target at Cave C, the experimental cave of the R 3 B (Reactions with Radioactive Relativistic Beams) collaboration at the GSI-FAIR facilities in Darmstadt, Germany. The findings obtained after the experiment indicate that there was no significant impact on the performance in terms of resolution and LONU. This suggests that the employed wrapping for light collection effectively serves as an excellent barrier against humidity. As a result, the crystal is preserved in a far better condition than initially anticipated.

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment

Studies based on imaging the annihilation of the electron (e−) and its antiparticle positron (e+) open up several interesting applications in nuclear medicine and fundamental research. The annihilation process involves both the direct conversion of e+ e− into photons and the formation of their atomically bound state, the positronium atom (Ps), which can be used as a probe for fundamental studies. With the ability to produce large quantities of Ps, manipulate them in a long-lived Ps states, and image their annihilations after a free fall or after passing through atomic interferometers, this purely leptonic antimatter system can be used to perform inertial sensing studies in view of a direct test of Einstein’s equivalence principle. It is envisioned that modular multi-strip detectors can be exploited as potential detection units for this kind of studies. In this work, we report the results of the first feasibility study performed on a e …

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment

Abstract Over the years, Maxwellian Averaged Cross Sections (MACS) have been measured by neutron activation, providing a neutron energy spectrum resembling the one found inside the stars. Recently, a new method has been proposed to produce stellar spectra at different stellar temperatures (a Maxwell–Boltzmann neutron energy distribution), employing the 7 Li (p, n) 7 Be reaction. The method is based on the idea of shaping the proton beam energy to shape the neutron beam spectrum. This method was applied to obtain a well-reproduced Maxwell–Boltzmann neutron spectrum (MBNS) at k T= 28 keV. An initial proton energy of 3170 keV and an aluminum foil as a proton energy shaper were employed. Differential angular neutron energy distributions from 0 to 90 degrees in 10∘ steps were measured to obtain the 0∘–90∘ integrated neutron spectrum over a neutron flight path of 50 cm. This manuscript …

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment

We report on a highly selective experimental setup for particle-γ coincidence experiments at the Super-Enge Split-Pole Spectrograph (SE-SPS) of the John D. Fox Superconducting Linear Accelerator Laboratory at Florida State University (FSU) using fast CeBr 3 scintillators for γ-ray detection. Specifically, we report on the results of characterization tests for the first five CeBr 3 scintillation detectors of the CeBr 3 Array (CeBrA) with respect to energy resolution and timing characteristics. We also present results from the first particle-γ coincidence experiments successfully performed with the CeBrA demonstrator and the FSU SE-SPS. We show that with the new setup, γ-decay branching ratios and particle-γ angular correlations can be measured very selectively using narrow excitation energy gates, which are possible thanks to the excellent particle energy resolution of the SE-SPS. In addition, we highlight that nuclear …

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment

In deep-underground experiments, intrinsic detector background can exceed the external one, limiting the detection sensitivity. Intrinsic background in liquid scintillator neutron detectors consists of α particles emitted from radioactive impurities in the detector housing (and possibly in the liquid). We present the results of long background measurements of 12 EJ-309 liquid organic scintillators detectors in the deep-underground Gran Sasso National Laboratory of the Italian Institute of Nuclear Physics. These detectors are a part of the detection array for the SHADES ERC project that aims to measure the very low cross section (down to picobarn) of the astrophysically important reaction 22 Ne (α, n) 25 Mg. With an exposure of∼ 35 days we identify an actinide concentration in the detector housing of 8. 4 (1. 8) sta (1. 4) sys× 1 0− 2 ppm and 1. 62 (0. 57) sta (0. 03) sys× 1 0− 1 ppm of 238 U and 232 Th, resulting in 64 α …

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment

The nozzle geometry has a significant impact on the nozzle internal flow, which affects the fuel spray atomization and combustion of internal combustion engine. In this study, the internal geometry and flow characteristics of the nozzle was studied visually by using X-ray phase contrast imaging technique. The results indicate that the angle between the orifice wall and sac significantly influences the formation and development of cavitation in the orifice. A numerical model including the nozzle internal flow and the spray near-field characteristics was established to provide a more detailed description of how the inlet included angle affects the orifice's internal flow. It has been found that the hydraulic flip width increases with the decrease of the inlet included angle. The symmetry of cavitation distribution is greater when the inlet included angles on the left and right sides of the orifice are equal. When the inlet included …

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment

An aerodynamic lens injector was developed specifically for the needs of single-particle diffractive imaging experiments at free-electron lasers. Its design allows for quick changes of injector geometries and focusing properties in order to optimize injection for specific individual samples. Here, we present results of its first use at the FLASH free-electron-laser facility. Recorded diffraction patterns of polystyrene spheres are modeled using Mie scattering, which allowed for the characterization of the particle beam under diffractive-imaging conditions and yielded good agreement with particle-trajectory simulations. The complex refractive index of polystyrene at λ= 4. 5 nm was determined as m= 0. 976− 0. 001 i.

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment

We report on a highly selective experimental setup for particle-γ coincidence experiments at the Super-Enge Split-Pole Spectrograph (SE-SPS) of the John D. Fox Superconducting Linear Accelerator Laboratory at Florida State University (FSU) using fast CeBr 3 scintillators for γ-ray detection. Specifically, we report on the results of characterization tests for the first five CeBr 3 scintillation detectors of the CeBr 3 Array (CeBrA) with respect to energy resolution and timing characteristics. We also present results from the first particle-γ coincidence experiments successfully performed with the CeBrA demonstrator and the FSU SE-SPS. We show that with the new setup, γ-decay branching ratios and particle-γ angular correlations can be measured very selectively using narrow excitation energy gates, which are possible thanks to the excellent particle energy resolution of the SE-SPS. In addition, we highlight that nuclear …

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment

The measurement of shower muons on an event-by-event basis offers a potent tool for conducting ground-based experiments on gamma rays and cosmic rays due to its sensitivity to primary mass and interaction models. In recent years, underground water Cherenkov detectors as large-area muon counters provide the most powerful way of rejecting cosmic ray background when searching for TeV–PeV gamma rays and cosmic ray electrons, an unprecedented rejection power of 1 0 4–1 0 5 is achieved. Unburied water Cherenkov detectors are widely used in ground-based gamma astronomy experiments, eg, Milagro, HAWC, LHAASO-WCDA, etc. However, due to the presence of electromagnetic components, their deployment as event-by-event muon counters has encountered considerable challenges. All the experiments mentioned above reconstruct lateral-distribution-function related parameters to tell a gamma …

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment

The measurement of shower muons on an event-by-event basis offers a potent tool for conducting ground-based experiments on gamma rays and cosmic rays due to its sensitivity to primary mass and interaction models. In recent years, underground water Cherenkov detectors as large-area muon counters provide the most powerful way of rejecting cosmic ray background when searching for TeV–PeV gamma rays and cosmic ray electrons, an unprecedented rejection power of 1 0 4–1 0 5 is achieved. Unburied water Cherenkov detectors are widely used in ground-based gamma astronomy experiments, eg, Milagro, HAWC, LHAASO-WCDA, etc. However, due to the presence of electromagnetic components, their deployment as event-by-event muon counters has encountered considerable challenges. All the experiments mentioned above reconstruct lateral-distribution-function related parameters to tell a gamma …

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment

Abstract The improved Resistive Plate Chambers (iRPC) are designed using thin low resistivity High-Pressure Laminate (HPL) gaps. They are proposed to equip the very forward region of the Compact Muon Solenoid (CMS) detector, as they can stand rates∼ 2 kHz/cm 2. To withstand 3 times higher rates than the installed CMS RPC chambers, the HPL electrode thickness was reduced from 2 mm to 1.4 mm. The gas gain of the detector is dependent on the gas pressure and temperature which requires correcting for the applied voltage to keep detector operational characteristics such as efficiency, cluster size and noise rate constant. Herein, we study the pressure correction at constant temperature for CMS iRPC and compare its correction coefficient with the one for the 2 mm RPC gap technology. Pressure correction parameters for both technologies are found compatible.

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment

The ANDROMeDa project, recently funded by the Italian ministry of research with a 1M€ grant, aims to develop a novel light dark matter (DM) detector sensitive to DM-electron recoil in a target of vertically-aligned carbon nanotubes: the “dark-PMT”. Thanks to their vanishing density in the direction of the tube axis, carbon nanotubes allow a scattered electron to leave the target without being re-absorbed only if it travels parallel to the tubes. Therefore the detector is expected to have directional sensitivity, a key feature in DM searches. With only 1 g of exposure per year and a careful suppression of the backgrounds, such detector might achieve world-leading sensitivity for DM masses below 30 MeV.

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment

For computed tomography (CT) imaging to be considered “real time”, one set of tomographic projections are to be acquired in less than 30 ms. Current conventional CT systems are limited to approximately 300 ms because of mechanical and material limitations. To bypass the mechanical limitations of a conventional gantry system, there is an open design challenge to develop a distributed X-ray source that is tightly packed and bright. The work presented here reports a design for a distributed X-ray source based on a rotating cylindrical anode. In particular, this work focuses on designing the electron beam optics for said X-ray source and refining these optics via multi-physics simulation studies. We designed these studies to investigate the electron beam behavior for switching, steering, and focusing. We demonstrated that the high-energy electron beam could be turned off and on via the grid-switching technique …

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment

Studies based on imaging the annihilation of the electron (e−) and its antiparticle positron (e+) open up several interesting applications in nuclear medicine and fundamental research. The annihilation process involves both the direct conversion of e+ e− into photons and the formation of their atomically bound state, the positronium atom (Ps), which can be used as a probe for fundamental studies. With the ability to produce large quantities of Ps, manipulate them in a long-lived Ps states, and image their annihilations after a free fall or after passing through atomic interferometers, this purely leptonic antimatter system can be used to perform inertial sensing studies in view of a direct test of Einstein’s equivalence principle. It is envisioned that modular multi-strip detectors can be exploited as potential detection units for this kind of studies. In this work, we report the results of the first feasibility study performed on a e …

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment

Neutron and gamma-ray imaging systems are deployed within the field of nuclear safeguards for the detection and localization of special nuclear materials and other materials of interest. 237Np is one of these materials of interest due its presence in spent nuclear fuel and potential for use in nuclear weapons when purified. Here, for the first time, a 6 kg neptunium sphere (98.8 wt% 237Np) was measured using a dual-particle imager, from the University of Michigan, consisting of organic glass and inorganic scintillators. The novel composition of organic glass scintillator was recently developed at Sandia National Labs and has been used in particle imaging systems due to its time resolution and particle discrimination capabilities. Gamma-ray energy spectra from single and coincident events were extracted and the sequencing of Compton scatter and photoelectric absorption gamma-ray events was used to generate …

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment

Abstract The Cherenkov Telescope Array Observatory (CTAO) will be the major global observatory for gamma-ray astronomy over the next decade and beyond. It will consist of two arrays of telescopes of different sizes, one for each hemisphere, and will be sensitive to gamma rays in the energy range from a few tens of GeV to hundreds of TeV. The Small-Sized Telescopes (SSTs) are a crucial component of the southern array, as they will extend the sensitivity of the observatory to the highest energies. Their focal plane will be equipped with 2048 Silicon Photomultiplier (SiPM) pixels, each one read independently by a state-of-the-art full waveform sampling readout. These solid-state sensors offer advantages over the traditional photomultiplier tubes, such as lower operating voltage, higher photon detection efficiency, and tolerance to bright illumination. In particular, they are the best choice for a small and compact …

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment

Abstract The HERMES (High Energy Rapid Modular Ensemble of Satellites) Pathfinder mission aims to develop a constellation of nanosatellites to study astronomical transient sources, such as gamma-ray bursts, in the X and soft γ energy range, exploiting a novel inorganic scintillator. This study presents the results obtained describing, with an empirical model, the unusually intense and long-lasting residual emission of the GAGG: Ce scintillating crystal after irradiating it with high energy protons (70 MeV) and ultraviolet light (∼ 300 nm). From the model so derived, the consequences of this residual luminescence for the detector performance in operational conditions has been analysed. The suitability of this detector for the HERMES Pathfinder nanosatellites was demonstrated by the low contribution of the afterglow, 1–2 pA at peak, to the input current of the front-end electronics.

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment

The development of advanced, high gradient accelerating structures is one of the leading activity of the particle accelerator community. In the technological research of new construction methods for these devices, high-power testing is a critical step for the verification of their viability. Recent experiments showed that accelerating cavities made out of hard copper, fabricated without high-temperature processes, can achieve better performance as compared with soft copper ones. Recently, we have built cavities using Tungsten Inert Gas welding and the high-power experiments confirmed that this joining process is a robust and low-cost alternative to brazing or diffusion bonding. This is a good solution for high-gradient operation, with a gradient of about 150 MV/m in X-band, at a breakdown rate of 1 0− 3/pulse/meter using a shaped RF pulse with a 150 ns flat part. We continue the design, construction and high power …

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment

We have been developing silicon-on-insulator (SOI) pixel detectors with a pinned depleted diode (PDD) structure, named “XRPIX”, for X-ray astronomy. The PDD structure is formed in a thick p-type substrate, to which high negative voltage is applied to make it fully depleted. A pinned p-well is introduced at the backside of the insulator layer to reduce a dark current generation at the Si-SiO2 interface and to fix the back-gate voltage of the SOI transistors. An n-well is further introduced between the p-well and the substrate to make a potential barrier between them and suppress a leakage current. An optimization study on the n-well dopant concentration is necessary because a higher dopant concentration could result in a higher potential barrier but also in a larger sense-node capacitance leading to a lower spectroscopic performance, and vice versa. Based on a device simulation, we fabricated five candidate chips …

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment

In view of the High Luminosity LHC, the CMS Muon system will be upgraded to sustain its efficient muon triggering and reconstruction performance. Resistive Plate Chambers (RPC) are dedicated detectors for muon triggering due to their excellent timing resolution. The RPC system will be extended up to 2.4 in pseudorapidity. Before the LHC Long Shutdown 3, new RE3/1 and RE4/1 stations of the forward Muon system will be equipped with improved Resistive Plate Chambers (iRPC) having, compared to the present RPC system, a different design and geometry and 2D strip readout. This advanced iRPC geometry configuration allows the rate capability to improve and hence survive the harsh background conditions during the HL-LHC phase. Several iRPC demonstrator chambers were installed in CMS during the recently completed 2nd Long Shutdown to study the detector behaviour under real LHC conditions …