Energy measurement of prompt fission neutrons in 239Pu(n,f) for incident neutron energies from 1 to 200 MeV

Prompt fission neutron spectra in the neutron-induced fission of 239Pu have been measured for incident neutron energies from 1 to 200 MeV at the Los Alamos Neutron Science Center. Preliminary results are discussed and compared to theoretical model calculation

Discovery and Cross-Section Measurement of Neutron-Rich Isotopes in the Element Range from Neodymium to Platinum at the FRS

With a new detector setup and the high-resolution performance of the fragment separator FRS at GSI we discovered 57 new isotopes in the atomic number range of 60$\leq Z \leq 78$: \nuc{159-161}{Nb}, \nuc{160-163}{Pm}, \nuc{163-166}Sm, \nuc{167-168}{Eu}, \nuc{167-171}{Gd}, \nuc{169-171}{Tb}, \nuc{171-174}{Dy}, \nuc{173-176}{Ho}, \nuc{176-178}{Er}, \nuc{178-181}{Tm}, \nuc{183-185}{Yb}, \nuc{187-188}{Lu}, \nuc{191}{Hf}, \nuc{193-194}{Ta}, \nuc{196-197}{W}, \nuc{199-200}{Re}, \nuc{201-203}{Os}, \nuc{204-205}{Ir} and \nuc{206-209}{Pt}. The new isotopes have been unambiguously identified in reactions with a $^{238}$U beam impinging on a Be target at 1 GeV/u. The isotopic production cross-section for the new isotopes have been measured and compared with predictions of different model calculations. In general, the ABRABLA and COFRA models agree better than a factor of two with the new data, whereas the semiempirical EPAX model deviates much more. Projectile fragmentation is the dominant reaction creating the new isotopes, whereas fission contributes significantly only up to about the element holmium.Comment: 9 pages, 4 figure

Measuring the CMB primordial B-modes with Bolometric Interferometry

The Q&U Bolometric Interferometer for Cosmology (QL’BIC) is the first bolometric interferometer designed to measure the primordial B-mode polarization of the Cosmic Microwave Background (CMB). Bolometric interferometry is a novel technique that combines the sensitivity of bolometric detectors with the control of systematic effects that is typical of interferometry, both key features in the quest for the faint signal of the primordial B-modes. A unique feature is the so-called “spectral imaging”, i.e., the ability to recover the sky signal in several sub-bands within the physical band during data analysis. This feature provides an in-band spectral resolution of ∆v/v ~ 0.04 that is unattainable by a traditional imager. This is a key tool for controlling the Galactic foregrounds contamination. In this paper, we describe the principles of bolometric interferometry, the current status of the QU BIC experiment and future prospects.Fil: Mennella, A.. Università degli Studi di Milano; Italia. Istituto Nazionale di Fisica Nucleare; ItaliaFil: Ade, P.. Cardiff University; Reino UnidoFil: Almela, Daniel Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Tecnología en Detección y Astropartículas. Comisión Nacional de Energía Atómica. Instituto de Tecnología en Detección y Astropartículas. Universidad Nacional de San Martín. Instituto de Tecnología en Detección y Astropartículas; ArgentinaFil: Amico, G.. Università di Roma; ItaliaFil: Arnaldi, Luis Horacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Tecnología en Detección y Astropartículas. Comisión Nacional de Energía Atómica. Instituto de Tecnología en Detección y Astropartículas. Universidad Nacional de San Martín. Instituto de Tecnología en Detección y Astropartículas; ArgentinaFil: Aumont, J.. Institut de Recherche en Astrophysique et Planétologie; FranciaFil: Banfi, S.. Università degli Studi di Milano; Italia. Istituto Nazionale di Fisica Nucleare; ItaliaFil: Battistelli, E. S.. Istituto Nazionale di Fisica Nucleare; Italia. Università degli Studi di Milano; ItaliaFil: Bélier, B.. Centre de Nanosciences et de Nanotechnologies; FranciaFil: Bergé, L.. Centre de Spectrométrie Nucléaire et de Spectrométrie de Masse; FranciaFil: Bernard, J.. Institut de Recherche en Astrophysique et Planétologie; FranciaFil: Bersanelli, M.. Università degli Studi di Milano; Italia. Istituto Nazionale di Fisica Nucleare; ItaliaFil: Bonaparte, J.. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes; ArgentinaFil: Bonilla Neira, Jesús David. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Tecnología en Detección y Astropartículas. Comisión Nacional de Energía Atómica. Instituto de Tecnología en Detección y Astropartículas. Universidad Nacional de San Martín. Instituto de Tecnología en Detección y Astropartículas; ArgentinaFil: Bunn, E.. University of Richmond; Estados UnidosFil: Buzi, D.. Università di Roma; ItaliaFil: Cacciotti, F.. Università di Roma; Italia. Istituto Nazionale di Fisica Nucleare; ItaliaFil: Camilieri, D.. Universite de Paris; Francia. Centre National de la Recherche Scientifique; FranciaFil: Cavaliere, F.. Università di Roma; Italia. Istituto Nazionale di Fisica Nucleare; ItaliaFil: Chanial, P.. Universite de Paris; Francia. Centre National de la Recherche Scientifique; FranciaFil: Chapron, C.. Universite de Paris; Francia. Centre National de la Recherche Scientifique; FranciaFil: Colombo, L.. Università degli Studi di Milano; Italia. Istituto Nazionale di Fisica Nucleare; ItaliaFil: Gomez Berisso, Mariano. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro. Archivo Histórico del Centro Atómico Bariloche e Instituto Balseiro | Universidad Nacional de Cuyo. Instituto Balseiro. Archivo Histórico del Centro Atómico Bariloche e Instituto Balseiro; ArgentinaFil: Tucker, G.. University of Wisconsin; Estados UnidosFil: Tucker, C.. Cardiff University; Reino UnidoFil: Vacher, L.. Centre National de la Recherche Scientifique; Francia. Institut de Recherche en Astrophysique et Planétologie; FranciaFil: Voisin, F.. Centre National de la Recherche Scientifique; Francia. Universite de Paris; FranciaFil: Wright, M.. University of Manchester; Reino UnidoFil: Zannoni, M.. Istituto Nazionale di Fisica Nucleare; Italia. Università degli Studi di Milano; ItaliaFil: Zullo, A.. Istituto Nazionale di Fisica Nucleare; Itali

New experimental approaches to investigate the fission dynamics

Abstract. The first ever achieved full identification of both fission fragments, in atomic and mass number, made it possible to define new observables sensitive to the fission dynamics along the fission path up to the scission point. Moreover, proton-induced fission of 208 Pb at high energies offers optimal conditions for the investigation of dissipative, and transient effects, because of the high-excitation energy of the fissioning nuclei, its low angular momentum, and limited shape distortion by the reaction. In this work we show that the charge distribution of the final fission fragments can constrain the ground-to-saddle dynamics while the mass distribution is sensitive to the dynamics until the scission point

Status of QUBIC, the Q&U Bolometer for Cosmology

The Q&U Bolometric Interferometer for Cosmology (QUBIC) is a novel kind of polarimeter optimized for the measurement of the B-mode polarization of the Cosmic Microwave Back-ground (CMB), which is one of the major challenges of observational cosmology. The signal is expected to be of the order of a few tens of nK, prone to instrumental systematic effects and polluted by various astrophysical foregrounds which can only be controlled through multichroic observations. QUBIC is designed to address these observational issues with a novel approach that combines the advantages of interferometry in terms of control of instrumental systematics with those of bolometric detectors in terms of wide-band, background-limited sensitivity.Comment: Contribution to the 2022 Cosmology session of the 33rd Rencontres de Blois. arXiv admin note: substantial text overlap with arXiv:2203.0894

QUBIC VI: cryogenic half wave plate rotator, design and performances

Inflation Gravity Waves B-Modes polarization detection is the ultimate goal of modern large angular scale cosmic microwave background (CMB) experiments around the world. A big effort is undergoing with the deployment of many ground-based, balloon-borne and satellite experiments using different methods to separate this faint polarized component from the incoming radiation. One of the largely used technique is the Stokes Polarimetry that uses a rotating half-wave plate (HWP) and a linear polarizer to separate and modulate the polarization components with low residual cross-polarization. This paper describes the QUBIC Stokes Polarimeter highlighting its design features and its performances. A common systematic with these devices is the generation of large spurious signals synchronous with the rotation and proportional to the emissivity of the optical elements. A key feature of the QUBIC Stokes Polarimeter is to operate at cryogenic temperature in order to minimize this unwanted component. Moving efficiently this large optical element at low temperature constitutes a big engineering challenge in order to reduce friction power dissipation. Big attention has been given during the designing phase to minimize the differential thermal contractions between parts. The rotation is driven by a stepper motor placed outside the cryostat to avoid thermal load dissipation at cryogenic temperature. The tests and the results presented in this work show that the QUBIC polarimeter can easily achieve a precision below 0.1{\deg} in positioning simply using the stepper motor precision and the optical absolute encoder. The rotation induces only few mK of extra power load on the second cryogenic stage (~ 8 K).Comment: Part of a series of 8 papers on QUBIC to be submitted to a special issue of JCA

A compact fission detector for fission-tagging neutron capture experiments with radioactive fissile isotopes

© 2020 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).In the measurement of neutron capture cross-sections of fissile isotopes, the fission channel is a source of background which can be removed efficiently using the so-called fission-tagging or fission-veto technique. For this purpose a new compact and fast fission chamber has been developed. The design criteria and technical description of the chamber are given within the context of a measurement of the 233U(n, γ) cross-section at the n_TOF facility at CERN, where it was coupled to the n_TOF Total Absorption Calorimeter. For this measurement the fission detector was optimized for time resolution, minimization of material in the neutron beam and for alpha-fission discrimination. The performance of the fission chamber and its application as a fission tagging detector are discussed.Peer reviewe