Institute Of Nuclear Physics Research Articles

Characterization of the INFN proton CT scanner for cross-calibration of x-ray CT

Objective. The goal of this study was to assess the imaging performances of the pCT system developed in the framework of INFN-funded (Italian National Institute of Nuclear Physics) research projects. The spatial resolution, noise power spectrum (NPS) and RSP accuracy has been investigated, as a preliminary step to implement a new cross-calibration method for x-ray CT (xCT). Approach. The INFN pCT apparatus, made of four planes of silicon micro-strip detectors and a YAG:Ce scintillating calorimeter, reconstructs 3D RSP maps by a filtered-back projection algorithm. The imaging performances (i.e. spatial resolution, NPS and RSP accuracy) of the pCT system were assessed on a custom-made phantom, made of plastic materials with different densities ((0.66, 2.18) g cm−3). For comparison, the same phantom was acquired with a clinical xCT system. Main results. The spatial resolution analysis revealed the nonlinearity of the imaging system, showing different imaging responses in air or water phantom background. Applying the Hann filter in the pCT reconstruction, it was possible to investigate the imaging potential of the system. Matching the spatial resolution value of the xCT (0.54 lp mm−1) and acquiring both with the same dose level (11.6 mGy), the pCT appeared to be less noisy than xCT, with an RSP standard deviation of 0.0063. Concerning the RSP accuracy, the measured mean absolute percentage errors were (0.23+−0.09)% in air and (0.21+−0.07)% in water. Significance. The obtained performances confirm that the INFN pCT system provides a very accurate RSP estimation, appearing to be a feasible clinical tool for verification and correction of xCT calibration in proton treatment planning.

Measurements of the neutron spectra from the p+Be neutron generator of the NPI CAS

The Nuclear Physics Institute of the Czech Academy of Sciences (NPI CAS) operates several neutron sources, including a generator of a continuous spectrum of neutrons up to 33 MeV. Accelerated protons from the U-120M cyclotron are directed to an 8 mm thick beryllium target to produce the neutrons.In this work, the neutron spectrum at distances of 3–8 m was directly measured with NE213 and stilbene scintillator detectors in the forward, diagonal and perpendicular directions. At a distance of 50 cm from the Be target, the neutron spectrum was validated with a gold activation detector. From previous work, the neutron spectra at close distances were characterized for use in high-intensity irradiation. Both the newly measured spectra at large distances and the previously measured spectrum were simulated using the Monte Carlo code, MCNP6.2, with ENDF7PROT and JENDL-4.0/HE nuclear data libraries. The comparison of the simulated and experimentally measured spectra revealed several limitations of both libraries.

Measurement of the Cross Section for the Neutron-Induced Fission of 238U Nuclei in the Energy Range of 0.3–500 MeV

The cross section for the neutron-induced fission of 238U nuclei has been measured using the time-of-flight spectrometer of the GNEIS neutron complex at the Petersburg Nuclear Physics Institute, National Research Center Kurchatov Institute, in the neutron energy range of 0.3–500 MeV. Fission fragments have been detected by low-pressure position-sensitive multiwire proportional counters. The cross section for 238U(n, f) fission has been measured with respect to the cross section for 235U(n, f) fission, which is an accepted international standard. Data on the energy dependence of the anisotropy of the angular distribution of fragments of neutron-induced 238U nuclei are also presented. The data obtained have been compared to previous experiments carried out using both similar and significantly different methods.

MACHINA, the Movable Accelerator for Cultural Heritage In-situ Non-destructive Analysis: project overview

Over the years, transportable instrumentation for cultural heritage (CH) in situ measurements has noticeably widespread, due to logistic, economical and safety reasons. Ion beam analysis, a powerful set of analytical techniques, of great importance for CH, is instead carried out by using fixed instrumentation. To overcome this limit, the Italian national Institute of Nuclear Physics (INFN), CERN (European Centre for Nuclear Research) and the Opificio delle Pietre Dure (OPD), started MACHINA, the “Movable Accelerator for CH In-situ Non-destructive Analysis: the new generation of accelerators for art” to build a transportable accelerator, compact, with strongly reduced weight, absorbed power and cost. MACHINA will be installed at the OPD and dedicated to CH. It will be moved to major conservation centres and museums, when needed. The INFN-CERN proposal, approved in December 2017, became operative in February 2018. 2018 was dedicated to the acquisition of material/instrumentations, to set up both a dummy accelerator (to test the vacuum system) and a vacuum chamber (to test the source). Due to COVID, in 2020 and 2021 the experimental work was slowed down, but we kept developing the control electronics/software and built the second-generation supporting structure. The HF-RFQ power supplies were integrated in October 2021. At the rise of 2022, after conditioning the cavities, we tested the system and in March 2022 we got the first extracted 2-MeV proton beam. In this paper, we present the structure of the MACHINA system, the approach followed and the main solutions adopted, with a special focus on the control system, and finally the first experimental results.

The new INFN-CHNet neutron imaging facility

In this paper, NICHE (Neutron Imaging for Cultural HEritage), the new neutron imaging facility of the Italian National Institute of Nuclear Physics (INFN) is shortly presented. We report on the main features of the beamline, the specifications of the detection set-up, and the performances of the imaging system. NICHE is installed at the TRIGA reactor of LENA (Laboratorio Energia Nucleare Applicata) Pavia University laboratory (Italy). The imaging facility was designed during 2020, installed in the spring 2021, and has been in operation since May 2021. NICHE is the first Italian neutron imaging station open to national external users through the INFN-CHNet network application system. NICHE allows users to obtain neutron radiographies and tomographies, thus allowing for morphological characterisation of samples. First results to highlight the potential of the facility are reported. In particular, we show the first results about spatial resolution measurement and 3D reconstruction to provide morphological analysis capabilities.

Search for Solar Sources of Interplanetary Coronal Mass Ejections Using the Reverse Model of Magnetodynamic Interaction of the Solar Wind in the Heliosphere

In the development and testing of methods for predicting interplanetary coronal mass ejections (ICMEs), it is important to establish their relationship with sources on the Sun—coronal mass ejections (CMEs) observed by coronagraphs. The often used inverse ballistic calculation of the CME onset time does not consider variations in the CME speed when moving through the heliosphere and can give an uncertainty up to a day. With a good accuracy (on the order of ±10 h), the propagation of CMEs in the heliosphere from the Sun to the Earth is described by the model of the magnetodynamic interaction of CMEs with the background solar wind (drag-based model, DBM). In this paper, we propose to search for possible coronal sources of ICMEs, observed near the Earth, using the reverse model of magnetodynamic interaction (reverse DBM, RDBM), which reconstructs in the reverse course the probable propagation of CMEs in the heliosphere and determines their outflow parameters in the solar corona using the measured ICME parameters. The model uses the speed of the background solar wind, which is calculated from the area of coronal holes in the central part of the Sun and presented on the website of the Space Monitoring Data Center of the Skobeltsyn Institute of Nuclear Physics, Moscow State University (SINP MSU), with correction factors.

Novel implementation of the INFN-CHNet X-ray fluorescence scanner for the study of ancient photographs, archaeological pottery, and rock art

INFN-CHNet is the cultural heritage network of the Italian National Institute of Nuclear Physics (INFN) and is constituted by units from Italy and from outside Europe, one of them at Universidad Nacional de San Martín (UNSAM) in Buenos Aires, Argentina. As a result of the initiative carried out during 2015 by the Accademia dei Lincei for the year of the Italian culture in Latin America, an INFN-CHNet laboratory was set at CEPyA-UNSAM with the collaboration of INFN and the Restoration Workshop Centro Tarea. Noteworthy, this laboratory is conceived as a multidisciplinary research facility with complementary skills, both scientific and humanistic. In this context, the first instrument jointly set up, optimised, and applied to Cultural Heritage was an X-ray fluorescence scanner. In this manuscript, we describe the instrument and its main features together with a set of representative yet novel applications in the field of cultural heritage, namely, the experimental study of hidden rock art through laboratory replicas that imitates the problems found in the archaeological sites (hematite drawings hidden below carbon deposition); the study and chemical characterisation of archaeological decorated pottery; and finally, the application of the XRF scanner to ancient photography, for quick and accurate identification of materials and techniques employed. Beyond these specific results, the primary output of this initiative has been the conception of a future network of scientific laboratories in South America, coordinated by CEPyA at UNSAM.

Principles and Applications of Accelerator Mass Spectrometry

Accelerator mass spectrometry (AMS) represents an ultrasensitive analytical method for measurement of long-lived radionuclides, namely 14C, 10Be, 26Al, 41Ca, 129I, and 236U. It provides information about isotopic ratios up to 10–16 in samples of mass from several miligrams to tens of micrograms. The first AMS laboratory in the Czech Republic was built in Nuclear Physics Institute, Řež, in collaboration with Archaeological Institute, Prague (both Czech Academy of Sciences) and Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, and equipped with AMS MIELA (Ionplus AG, Switzerland). This review summarizes history, principles, and use of this unique analytical method.

Neutron screen method for axial uniformity in silicon ingots for neutron transmutation doping at WWR-K reactor

In 2017, Institute of Nuclear Physics and Chiyoda Technol Corporation signed agreement on cooperation in research and development of technology for neutron-transmutation doping of large-sized silicon with a diameter of more than 6 in. and a height of up to 500 mm for the WWR-K reactor.The goal of the study is to reduce an irregularity in the electrical resistivity over the volume of the silicon ingot to (3–4)%. In view of reduction of the height irregularity factor, thermal neutron-absorbing materials are used, whereas an electric motor, which provides rotation of silicon ingot around its axis, is used to reduce the radial irregularity. The object of investigation is an aluminum block, which is a model of silicon ingot.This work presents the obtained at the critical facility results of the study the application of the screen method to the reduction of the height irregularity for doping in large-size silicon ingots.

On the multipole mixing ratio of the 1066 keV transition from the 0.52 μs isomer of 180Hf

The nucleus 180Hf is one of the most primary examples of an axially symmetric prolate rotor. Combined with the presence of high-K isomers, spectroscopic studies can provide important information on the nature of its single-particle levels. Precise measurements are essential for constraining nuclear models and interpreting the nature of such isomeric states. In this work, the nucleus 180Hf was populated using the proton pick-up reaction 181Ta(11B,12C)180Hf at beam energy of 47 MeV at Horia Hulubei National Institute of Nuclear Physics and Engineering (IFIN-HH). The spin of the 1374 keV state and the mixing ratio of the 1066 keV transition have been measured, the latter with an increased precision compared to the previous value from literature. The presently measured spin of the 1374 keV state, currently assigned a tentative value of (41−), favors one of the two different values that were previously reported. The particular state constitutes the band-head of a rotational band in 180Hf. The measured multipolarity mixing ratio of the inter-band transition 1374→309 keV can provide important information for the testing and constraining of theoretical nuclear models used for the study of the intrinsic properties of 180Hf, as well as its neighboring isotopes.

Experience in dynamic tape drive allocation to manage scientific data

The main computing and storage facility of INFN (Italian Institute for Nuclear Physics) running at CNAF hosts and manages tens of Petabytes of data produced by the LHC (Large Hadron Collider) experiments at CERN and other scientific collaborations in which INFN is involved. Most of these data are stored on tape resources of different technologies. All the tape drives can be used for administrative tasks (as repack, audit, space reclamation), as well to write and read data of all the experiments. Moreover, the usage of tape resources by scientific communities will become considerably more intense in the next years and the amount of data on tape will double by 2025. For these reasons, the issue of the concurrent access to tape drives is significant. We designed a software solution to optimize the efficiency of the shared usage of tape drives in our environment and put it in production in January 2020. In this paper we present the experience with such dynamic tape resources allocation in production. Comparing it with the previous static allocation method, we observed an improvement in reading throughput up to 85%. Moreover, we describe the new features added to our solution to optimize the efficiency of the shared usage of tape drives of different technologies.

EOS deployment on Ceph RBD/CephFS with K8s

The present activity focused on the integration of different storage systems (EOS [1] and Ceph [2]) with the aim to combine the high level scalability and stability of EOS services with the reliability and redundancy features provided by Ceph. The work has been carried out as part of the collaboration between the national center of INFN (Italian Institute for Nuclear Physics) dedicated to Research and Development on Information and Communication Technologies and the Conseil Européen pour la Recherche Nucléaire (CERN), with the goal of evaluating and testing different technologies for next-generation storage challenges. This work leverages the well-known open-source container orchestration system, Kubernetes [3], for managing file system services. The results obtained by measuring the performances of the different combined technologies, comparing for instance block device and file system as backend options provided by a Ceph cluster deployed on physical machines, are shown and discussed in the manuscript.

Analyzing cosmic-ray muons in the experimental paths of the “Mathematical High School” Project

The Mathematical High School (MHS) Project is a research project involving 160 high schools and 26 Italian universities in which experimental research paths are deepened to explore mathematics as a universal language and as a link between the various areas of both humanistic and scientific knowledge. These activities are developed with the collaboration of internationally recognized research institutions. In particular, in the MHS schools, the research group of the Mathematics Department of the University of Salerno in collaboration with INFN (National Institute of Nuclear Physics) Naples division, offers laboratory activities of data analysis on cosmic rays. Students, guided by the researchers, use the CRC (Cosmic Rays Cube), a portable muon detector, to carry out an experimental activity, from the data taking to the analysis. They study what cosmic rays are, where they come from and, in particular, the characteristics of comic-ray muons produced in the Earth atmosphere. Mathematics becomes the instrument to interpret data collected by the detector, measure the muon flux and reconstruct their direction. Using dedicated software, students experience the activity of the researchers. Working in team, they deal with high-profile scientific issues usually not developed in the curricular educational paths.

Application of Accelerator Beam Dumps for Dark Matter Searches

Light dark matter (LDM) in the mega-electron-volt to giga-electron-volt mass region is an attractive candidate for the all-pervasive and encompassing matter making up the vast bulk of the mass of our universe. Beam dump experiments at high-intensity accelerators are a powerful tool to produce and detect LDM. They can probe an unexplored dark sector that is interacting with the standard model (SM) through one or more portals. At the lowest-beam-energy end, the DarkMESA experiment will run behind the dump of the 150-MeV electron beam of the MESA accelerator, currently under construction at the Institute for Nuclear Physics in Mainz. The concept for detecting direct scattering reactions of LDM comprises an electromagnetic calorimeter surrounded by an active veto system for rejecting backgrounds from SM particles. Suitable shielding will be located between the downstream detectors and the dump. A low-pressure, negative-ion, time-projection chamber could supplement these searches. At much higher beam energies, the Beam Dump eXperiment (BDX) is proposed to run parasitically behind the Jefferson Lab Hall-A beam dump making use of the up to 11-GeV electron beam. BDX employs the same detector concept. Direct LDM scattering reactions can be detected in an electromagnetic calorimeter operated inside hermetic layers of veto counters and a thick lead vault. Both experiments can explore uncovered regions of the parameter space of the LDM interaction strength versus mass, exceeding the discovery potential of existing experiments.

1D/2D benchmark experiments of aluminum alloy irradiated by 14 MeV neutrons for ICF facilities

Aluminum alloy (5083) is one of the most important structural materials used in laser-driven Inertial Confinement Fusion (ICF) facilities, which will be exposed to high-yield 14 MeV neutrons and highly activated after the DT explosion. Reliable estimation of shutdown dose rate levels is of great importance for machine operation planning and to ensure the safety of people entering into target bay. Both 1D and 2D benchmark experiments were performed on a DT neutron accelerator at the Institute of Nuclear Physics and Chemistry (INPC) to validate the calculation codes and cross section libraries (JMCT with FENDL-3.1d and FISPACT with EAF-2007) used in the simulations of neutron transport and activation for aluminum alloy 5083. The total neutron yield was about 6 × 1014 in the experiments. Both radioactivity of foils placed inside the assembly and air kerma rate at given positions out of the assembly have been measured in 1D/2D experiments. Monte-Carlo code JMCT with FENDL-3.1d was used in both neutron and gamma-ray transport, and the inventory code FISPACT with EAF-2007 was used to calculate neutron activation. Results show that the relative error for air kerma rate in simulations and experiments is less than 20%, and radioisotopes give different contribution ratios on dose levels for 1D/2D experimental assemblies after DT neutron irradiation, especially for 24Na, 27Mg and 56Mn at the time within 16 h after neutron irradiated. Besides, simulations of radioactivity give good agreement with experimental results obtained for radioisotopes 24Na, 196Au, 57Ni and 58Co in both 1D and 2D experiments, and the relative error is less than ±16%.

VITA high flux neutron source for various applications

A high flux neutron source based on a vacuum-insulated tandem accelerator (VITA) and a lithium target has been proposed and developed at the Budker Institute of Nuclear Physics in Novosibirsk, Russia. We describe VITA which provides a dc proton/deuteron beam with an energy within a range of 0.6–2.3 MeV with a current from 1 nA to 10 mA. VITA is also capable of producing α-particles through the 7Li(p,α)α and 11B(p,α) α α reactions, 478 keV photons through the 7Li(p,p ′ γ)7Li reaction and positrons through the 19F(p,e+e−)16O reaction. We present several applications of this source: boron neutron capture therapy, nuclear cross sections determination, lithium target study, radiation blistering of metals during proton implantation and the radiation testing of promising materials.

TOPAS simulations of the response of a mini-TEPC: benchmark with experimental data

Objective. Microdosimetry offers a fast tool for radiation quality (RQ) verification to be implemented in treatment planning systems in proton therapy based on variable LET or RBE to move forward from the use of a fixed RBE of 1.1. It is known that the RBE of protons can increase up to 50% higher than that value in the last few millimetres of their range. Microdosimetry can be performed both experimentally and by means of Monte Carlo (MC) simulations. This paper has the aim of comparing the two approaches. Approach. Experimental measurements have been performed using a miniaturized Tissue equivalent proportional counter developed at the Legnaro National Laboratories of the Italian National Institute for Nuclear Physics with the aim of being used as RQ monitors for high intensity beams. MC simulations have been performed using the microdosimetric extension of TOPAS which provides optimized parameters and scorers for this application. Main results. Simulations were compared with experimental microdosimetric spectra in terms of shape of the spectra and their average values. Moreover, the latter have been investigated as possible estimators of LET obtained with the same MC code. The shape of the spectra is in general consistent with the experimental distributions and the average values of the distributions in both cases can predict the RQ increase with depth. Significance. This study aims at the comparison of microdosimetric spectra obtained from both experimental measurements and the microdosimetric extension of TOPAS in the same radiation field.

Development of UCN sources at PNPI

This article reviews the development of various sources for ultracold neutrons (UCNs) at the Petersburg Nuclear Physics Institute (PNPI). For 45 years, PNPI has proposed and manufactured cryogenic devices for neutron conversion to low energies. Based on beryllium, hydrogen and deuterium, they can be operated in the intense radiation fields near the core of a nuclear reactor. A more recently launched UCN source development utilizes superfluid helium (He-II) as conversion medium. Initially proposed and designed for PNPI’s old WWR-M reactor, the project has been reshaped to equip the institute’s PIK reactor with a modern UCN source of this type. The projected UCN density in the closed source chamber is 2.2 × 103 cm−3, which, as calculations of neutron transport show, will provide 200 cm−3 in the chambers of a neutron EDM spectrometer connected to the source by a UCN guide. Experiments at PNPI with a full-scale UCN source model have demonstrated that a heat load of 60 W can be removed from the He-II in the converter at a temperature of 1.37 K. This fact confirms the practical possibility to implement low-temperature converters under “in-pile” conditions with large heat inflows. The review concludes with a presentation of various proposed options for a He-II based UCN source at the European Spallation Source.

Background gamma measurement for low energy astrophysical reaction at FRENA

The majority of astrophysical reactions have very low cross-sections (nanobarn to picobarn range) and significant error bars [1, 2]. Hence γ-ray background studies up to 3 MeV have been performed inside the Facility for Research in Experimental Nuclear Astrophysics (FRENA), Saha Institute of Nuclear Physics, Kolkata, India. A meticulous background calculation has been performed at different positions inside the accelerator hall and beam hall using two NaI(Tl) detectors [3]. An XPS measurement has been carried out to identify elements present in the FRENA wall concrete. Activity calculations done in [4] shows that neutrons produced by various experiments may combine with any nearby elements and form various radioactive isotopes with long half-lives, which may produce a γ-ray background .

Time-Series Deep Learning Anomaly Detection for Particle Accelerators

High energy particle accelerators rely on superconducting radio frequency cavities to transfer energy and accelerate the beam. Such particle accelerators are complex and expensive systems prone to failures which lead to downtime of the whole experimental facility: it is thus of primary importance to anticipate and prevent these faults to improve the uptime and cost-effectiveness of particle accelerators. Data-driven methods are especially fit for this task as they can leverage all the data recorded and archived by a typical control system. Previous works used classical machine learning (ML) models for anomaly detection to detect early signs of an upcoming fault. We propose here a different approach based on deep learning (DL) models, exploiting the temporal correlation of the raw data. Three different models are tested on data from the ALPI (Linear Accelerator for Ions) linear accelerator in INFN (National Institute for Nuclear Physics) Legnaro National Laboratories in Italy and they are compared with the classical ML approach.