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155,157Gd neutron capture cross sections measured at n TOF (CERN)
Get PDFThe accurate knowledge of the neutron capture cross sections of 155Gd and 157Gd plays an important in many fields of science. Despite of its importance, only few experimental data are available on these two isotopes in the low energy region. For this purpose, a measurement of the neutron capture cross-sections of the two odd Gd isotopes was carried out at the experimental area (EAR1) of the n TOF facility at CERN. In this work, the main results obtained in the thermal region as well as in the resolved resonance region, will be presented
Track reconstruction in the FOOT experiment
Get PDFThe FOOT experiment is a fixed target experiment aiming for high precision (better than 5%) measurement of fragmentation cross section for hadrontherapy and space radioprotection purposes. Both target and projectile fragmentation are studied by using mainly proton, Carbon and Oxygen ion beams in both direct and inverse kinematic regime, alternatively. A good track reconstruction and momentum measurement is of fundamental importance for precise fragment identification and cross section measurement
The K+ → π+νν¯ decay: First results from the NA62 experiment
Get PDFNA62 is a fixed target experiment installed in the CERN North Area that studies the physics of the K+ meson. Its main purpose is to carry out a precision test of the Standard Model, measuring the branching ratio of the ultra-rare K+ → π+νν¯ decay with a 10% precision, then probing New Physics evidence. NA62 collected data in 2016 and 2017, and the 2018 run is going on. The full 2016 data sample has been analysed. It shows that the new in flight technique for the study of the K+ → π+νν¯ decay works, and 1 signal candidate event has been observed
Statistical behaviour of a proxy of the entropy production rate of the solar photosphere
Get PDFThe solar photosphere provides an incomparable laboratory to study turbulent convection in a dissipative non-equilibrium system. The evaluation of the entropy production rate on the solar photosphere and its probability distribution are the key issues for studying the non-equilibrium dynamics of the solar convection. The local entropy production rate is not offhandedly measurable on the solar photosphere, but it can be easily evaluated using the vertical heat flux as a proxy, which is given by the product between the line-of-sight velocity and the surface temperature. In this work, we present some preliminary results on statistics of the local entropy production rate via the vertical heat flux, using line-of-sight velocity and temperature maps of the solar photosphere which are derived from high-resolution spectro-polarimetric data making use of the Center of Gravity Method and the Stefan-Boltzmann law
Recent insights on the penumbra formation process
Get PDFUsing high-resolution spectropolarimetric data acquired by IBIS, as well as SDO/HMI observations, we studied the penumbra formation in AR NOAA 11490 and in a sample of twelve ARs appeared on the solar disk on 2011 and 2012, which were characterized by β-type magnetic field configuration. The results show that the onset of the classical Evershed flow occurs in a very short time scale, 1-3 hours. Studying the formation of the first penumbral sector around the following proto-spot, we found that a stable penumbra forms in the area facing the opposite polarity, which appears to be co-spatial with an AFS, i.e. in a flux emergence region, in contrast with the results of the paper Schlichenmaier R., Rezaei R. et al., Astron. Astrophys., 512 (2010) L1 concerning the leading polarity of AR NOAA 11490. Conversely, analyzing the sample of twelve ARs, we noticed that there is not a preferred location for the formation of the first penumbral sector. We also observed before the penumbra formation an inverse Evershed flow, which changes its sign when the penumbra appears. This confirms the observational evidence that the appearance of the penumbral filaments is correlated with the transition from the inverse Evershed to the classical Evershed flow. Furthermore, the analysis suggests that the time needed to form the penumbra may be related to the location where the penumbra first appears. New high-resolution observations, like those that will be provided by the European Solar Telescope, are expected to increase our understanding of the penumbra formation process
Metrology on-board PROBA-3: The Shadow Position Sensor (SPS) subsystem
Get PDFPROBA-3 is an ESA Mission whose aim is to demonstrate the in-orbit Formation Flying and attitude control capabilities of its two satellites by means of closed-loop, on-board metrology. The two small spacecraft will form a giant externally occulted coronagraph that will observe in visible polarized light the inner part of the solar corona. The SPS subsystem is composed of eight sensors that will measure, with the required sensitivity and dynamic range, the penumbra light intensity around the coronagraph instrument entrance pupil
Long-term heliomagnetic field variation based on cosmogenic 44Ti in meteorites
Get PDFReconstructions of the heliospheric magnetic field (HMF) in the past centuries are mainly based on the analysis of sunspot activity, geomagnetic data or on measurement of cosmogenic radioisotopes stored in terrestrial reservoirs (tree rings and ice cores). There are, however, significant discrepancies among the results obtained by various techniques using different proxies of solar magnetic activity. In this work, new results obtained from a unique approach based on the measurement of the cosmogenic 44Ti activity detected in meteorites are presented and compared with the most recent reconstructions of the near-Earth HMF strength. The very low level of 44Ti activity in several meteorites fallen in the last 250 years was determined by using gamma-ray spectrometers (HPGe+NaI) located in the underground laboratory of Monte dei Cappuccini (INAF-OATo) in Torino, Italy. This approach, specifically designed to overcome the main problems affecting other methods, yields a powerful independent tool to reconstruct the long-term evolution of the HMF through the last two and a half centuries
Status and perspectives of the neutron time-of-flight facility n_TOF at CERN
Get PDFThe neutron time-of-flight facility of CERN, called n TOF, started its operation in 2001, and since then it plays a major role in the field of neutron cross-section measurements. The two beam-lines available provide an excellent combination of good energy resolution and high instantaneous neutron flux, combining the time-of-flight method with a powerful neutron spallation source. So far, a large number of experiments has been performed on a variety of isotopes of interest for nuclear astrophysics, advanced nuclear technologies, nuclear medicine, and for basic nuclear physics. After the CERN long shutdown, a new phase of data taking is planned to start in 2021. The R&D of a new spallation target is ongoing and its upgrade will bring important improvements in both beam lines, allowing the n TOF
Collaboration to perform new, challenging measurements
The Endcap Disc DIRC for PANDA at FAIR
Get PDFThe Endcap Disc DIRC for the PANDA experiment is going to provide an excellent particle identification up to particle momenta of 4 GeV/c. It covers the polar angles from 5◦ to 22◦ and guarantees a separation power of more than 3
standard deviations (s.d.) for pions and kaons in the required phase space. The simulated detector performance has been validated during several testbeam campaigns.
Additionally, the transmission losses of the optical filter has been investigated to estimate the filter performance at the end of the PANDA lifetime
The Phase 0 of the NEPIR project at LNL
Get PDFNEPIR (Neutron and Proton Irradiation facility) is the project of a new irradiation facility at INFN Legnaro National Laboratories (LNL). The facility will exploit the LNL 35-70 MeV high current proton cyclotron of the SPES complex, to feed two different compact neutron sources in order to generate high flux neutron beams with different energy spectra: quasi-monoenergetic neutron beams and atmospheric-like neutrons. This contribution focuses on the first stage of the construction of the facility: the NEPIR Phase 0, financed and in an advanced design phase. It will use a Be neutron production target capable of delivering up to ∼ 2 × 106 n cm−2 s −1