E. Chiaveri

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Status and outlook of the neutron time-of-flight facility n_TOF at CERN

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2007

The neutron time-of-flight facility n_TOF at CERN, fully operational since 2002, combines a high ... more The neutron time-of-flight facility n_TOF at CERN, fully operational since 2002, combines a high instantaneous neutron flux with high energy resolution. The wide energy range and the high neutron flux per time-of-flight burst result in a much enhanced signal to background ratio for neutron capture of radioactive isotopes and makes this facility well suited for the measurement of high quality neutron-induced reaction cross-sections. Neutrons are created by spallation reactions induced by a pulsed 20 GeV/c proton beam impinging on a lead target. A 5 cm water slab surrounding the lead target serves as a coolant and at the same time as a moderator of the spallation neutron spectrum, providing a wide energy spectrum from 0.1 eV to about 250 MeV. By the end of 2005, a first phase of data taking has been successfully terminated. Fission and capture experiments have been performed on a variety of isotopes of interest for nuclear astrophysics, advanced nuclear technologies and for basic nuclear physics. The instrumentation developed for this facility consists of parallel plate avalanche counter and fission ionization chamber detectors for the fission experiments and of low mass C 6 D 6 detectors and a 4 pi BaF 2 total absorption calorimeter for capture experiments. A new data acquisition system, based on sampling of the detector signals, has been developed to cope with the high count rates and to minimize the effective dead time to only a few tens of nanosecond. A second phase of data taking is planned to start in 2007, after an upgrade of the spallation target. On the longer term, the construction of a flight path at 20 m resulting in an increased neutron flux of about a factor of 100 opens new possibilities.

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Neutron cross-sections for next generation reactors: New data from n_TOF

Applied Radiation and Isotopes, 2010

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The n_TOF Facility at CERN: Performances and First Physics Results

AIP Conference Proceedings, 2005

The neutron Time of Flight (n_TOF) facility at CERN is a source of a wide-range (1 eV<E n <250 Me... more The neutron Time of Flight (n_TOF) facility at CERN is a source of a wide-range (1 eV<E n <250 MeV) flux of neutrons, generated by spallation of 20-GeV/c protons onto a solid lead target. The goal of the n_TOF is to provide unprecedented precision in neutron kinetic energy determination, which will in turn bring the much-needed precision in neutron-induced cross-section measurements. The unique features of the n_TOF facility (instantaneously very intense neutron flux, low duty cycle, high resolution, and low background) make possible the measurement of highly radioactive isotopes usually available in small quantities. Such measurements are vital for a range of studies in fields as diverse as nuclear technology, astrophysics, and fundamental nuclear physics. In this paper, the characteristics of the n_TOF facility will be described, together with the main features of the highperformance detectors and acquisition system used for cross-section measurements, with a summary of the results and experience acquired during the first years of operation.

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Construction and Testing of a 161 MHZ, BETA=0.16 Superconducting QWR with Steering Correction for Ria

We have built a 161 MHz, b=0.16 superconducting Quarter Wave Resonator with steering correction f... more We have built a 161 MHz, b=0.16 superconducting Quarter Wave Resonator with steering correction for the low beta section of RIA. This bulk niobium, double wall cavity, compatible with both separate vacuum between beam line and cryostats or unified one, was designed in collaboration between MSU-NSCL and LNL. The design is suitable for extension to other frequencies, e.g. to obtain

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High Power tests of The prototype 352 MHz beta 0.85 five cell cavity for the Trasco project

The Five-cell beta 0.85 cavities built at CERN for the development of the TRASCO project is fully... more The Five-cell beta 0.85 cavities built at CERN for the development of the TRASCO project is fully tested at the CERN SL-CT Test Bench. The cavity, built using the standard Niobium on Copper technique, was previously tested in a vertical cryostat, showing Qo and Field exceeding the design goal for the Trasco Project (2.5x10 9 and 5.5 MV/m @ 4.5 K). After the successful test we decided to check the performances of the cavity installed in a horizontal Cryostat and equipped with a LEP-II Type high power main coupler and HOM couplers. The cavity was equipped with the Helium Tank, Tuners and couplers at CERN and tested at the SL-CT facility at Cern under a collaboration agreement between INFN and CERN. The behavior of the fully equipped cavity substantially confirmed the results of the preliminary production tests in the vertical Cryostat. The quality factor at low field was substantially unchanged. No MP activity was detected confirming the soundness of the design and the quality of the ...

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Experimental neutron capture data of 58Ni from the CERN n_TOF facility

EPJ Web of Conferences, 2015

Neutron capture cross-section of 155,157Gadolinium View project n_TOF: challenging measurements o... more

format_quoten_TOF results confirm earlier findings for kT=30 keV but deviate over 5% for temperatures above 70 keV, suggesting discrepancies in cross-section evaluations.format_quote

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Successful beam test of the HOM free superconducting SOLEIL cavity prototype at the ESRF

Proceedings of the 2003 Bipolar/BiCMOS Circuits and Technology Meeting (IEEE Cat. No.03CH37440), 2003

A cryo-module housing two strongly HOM damped 352 MHz superconducting (SC) cavity cells has been ... more A cryo-module housing two strongly HOM damped 352 MHz superconducting (SC) cavity cells has been developed within the framework of the SOLEIL project design phase. In 2002, the prototype was installed in the ESRF storage ring and tested with beam in the accelerating regime with the cavities cooled down to 4.5 K by means of liquid helium from Dewars. Four series of tests have been carried out at the end of scheduled shutdowns. In order not to disturb the ESRF machine performance during the user mode of operation, the cavities were maintained detuned at room temperature. In this passive regime, they remained transparent to the beam with less than 100 W of heat deposited by the beam and evacuated by a warm helium gas flow.

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LHC Collimation: Design and Results from Prototyping and Beam Tests

Proceedings of the 2005 Particle Accelerator Conference, 2005

The problem of collimation and beam cleaning is one of the most challenging aspects of the LHC pr... more The problem of collimation and beam cleaning is one of the most challenging aspects of the LHC project. A collimation system must be designed, built, installed and commissioned with parameters that extend the present state-of-the-art by 2-3 orders of magnitude. Problems include robustness, cleaning efficiency, impedance and operational aspects. A strong design effort has been performed at CERN over the last two years. The adopted phased approach is described. Robust and precisely controllable collimators have been designed. Several LHC prototype collimators have been built and tested with the highest beam intensities that are presently available at CERN. The successful beam tests are presented, including beam-based setup procedures, a 2 MJ robustness test and measurements of the collimator-induced impedance. Finally, an outlook is presented on the challenges that are ahead in the coming years.

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A Micromegas Detector for Neutron Beam Imaging at the n_TOF Facility at CERN

Nuclear Data Sheets, 2014

ABSTRACT Micromegas (Micro-MEsh Gaseous Structure) detectors are gas detectors consisting of a st... more ABSTRACT Micromegas (Micro-MEsh Gaseous Structure) detectors are gas detectors consisting of a stack of one ionization and one proportional chamber. A micromesh separates the two communicating regions, where two different electric fields establish respectively a charge drift and a charge multiplication regime. The n_TOF facility at CERN provides a white neutron beam (from thermal up to GeV neutrons) for neutron induced cross section measurements. These measurements need a perfect knowlodge of the incident neutron beam, in particular regarding its spatial profile. A position sensitive micromegas detector equipped with a 10B based neutron/charged particle converter has been extensively used at the n_TOF facility for characterizing the neutron beam profile and extracting the beam interception factor for samples of different size. The boron converter allowed to scan the energy region of interest for neutron induced capture reactions as a function of the neutron energy, determined by the time of flight. Experimental results will be presented and compared to simulations, performed by means of the FLUKA code.

Measurement of the 241Am and the 243Am Neutron Capture Cross Sections at the n_TOF Facility at CERN

Nuclear Data Sheets, 2014

ABSTRACT The capture cross sections of 241Am and 243Am were measured at the n_TOF facility at CER... more ABSTRACT The capture cross sections of 241Am and 243Am were measured at the n_TOF facility at CERN in the epithermal energy range with a BaF Total Absorption Calorimeter. A preliminary analysis of the 241Am and a complete analysis of the 243Am measurement, including the data reduction and the resonance analysis, have been performed.

Fission Fragment Angular Distribution of 232Th(n,f) at the CERN n_TOF Facility

Nuclear Data Sheets, 2014

Neutron capture cross-section of 155,157Gadolinium View project n_TOF: challenging measurements o... more

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Capture Cross Section of 236U: the n_TOF Results

Nuclear Data Sheets, 2014

ABSTRACT Neutron induced capture cross section on 236U has been measured with high accuracy and h... more

Spin Measurements of n +87Sr for Level Density Studies

Nuclear Data Sheets, 2014

ABSTRACT We have used the 4π BaF gamma-ray detector array at the n_TOF neutron time-of-flight fac... more ABSTRACT We have used the 4π BaF gamma-ray detector array at the n_TOF neutron time-of-flight facility at CERN for an experiment in order to determine the spins of resonances of n +87Sr by measuring the gamma-ray spectra and multiplicity distributions. The first results are presented here. We have assigned the orbital momentum ℓ to all evaluated resonances on the basis of their neutron widths. Further we have assigned the spin J to 16 s-wave resonances on based the population of low-lying levels.

Neutron cross-sections for advanced nuclear systems: the n_TOF project at CERN

EPJ Web of Conferences, 2014

High-accuracy determination of the U 238 / U 235 fission cross section ratio up to ≈ 1 GeV at n_TOF at CERN

Physical Review C, 2015

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RF testing of the TRASCO superconducting reentrant cavity for high intensity proton beams

A superconducting reentrant cavity for low beta, high intensity proton beams has been designed, b... more A superconducting reentrant cavity for low beta, high intensity proton beams has been designed, built and tested at LNL after chemical polishing at CERN. This single gap resonator is a prototype for the low beta section of the TRASCO 30 mA proton linac, designed aiming at full beam transmission even in case of failure of one resonator. Rf performance, multipacting and mechanical response of the cavity in the first low power tests will be reported.

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Commissioning of the n-TOF-Ph2 facility-192

$Research paper thumbnail of Reference measurement of the high energy (n, $\ αlpha $) cross section of $^{10} $ B with a CVD diamond detector for the prospect of future applications$

Reference measurement of the high energy (n, $\ αlpha $) cross section of $^{10} $ B with a CVD diamond detector for the prospect of future applications

Microwave apparatus for gravitational waves observation

In this report the theoretical and experimental activities for the development of superconducting... more

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The superconducting medium beta prototype for radioactive beam acceleration at TRIUMF

PACS2001. Proceedings of the 2001 Particle Accelerator Conference (Cat. No.01CH37268), 2001

A 106.08MHz superconducting quarter wave resonator, based on the bulk niobium technology develope... more

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