Neutron resonance spectroscopy at n_TOF at CERN

During 2014, the second experimental area (EAR2) was completed at the n-TOF neutron beam facility at CERN (n-TOF indicates neutron beam measurements by means of time of flight technique). The neutrons are produced via spallation, by means of a high-intensity 20 GeV pulsed proton beam impinging on a thick target. The resulting neutron beam covers the energy range from thermal to several GeV. In this paper, we describe two beam diagnostic devices, both exploiting silicon detectors coupled with neutron converter foils containing (6)Li. The first one is based on four silicon pads and allows monitoring of the neutron beam flux as a function of the neutron energy. The second one, in beam and based on position sensitive silicon detectors, is intended for the reconstruction of the beam profile, again as a function of the neutron energy. Several electronic setups have been explored in order to overcome the issues related to the gamma flash, namely, a huge pulse present at the start of each neutron bunch which may blind the detectors for some time. The two devices were characterized with radioactive sources and also tested at the n-TOF facility at CERN. The wide energy and intensity range they proved capable of sustaining made them attractive and suitable to be used in both EAR1 and EAR2 n-TOF experimental areas, where they became immediately operational.

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“…We summarize here the basic features of the n-TOF facility, whose full description can be found in refs. [3], [4].…”

Section: Introductionmentioning

confidence: 99%

Silicon detectors for monitoring neutron beams in n-TOF beamlines

Coséntino

Musumarra

Barbagallo

et al. 2015

Review of Scientific Instruments

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“…Conversely, the tritons crossed the ∆E and were stopped in the E layer, releasing respectively 1 and 1.7 MeV (nominal values when tritons are emitted from the very front face of the sample and impinge perpendicularly on the detector). Figure 8 shows the ∆E-E scatter plot measured in the test reaction (1). The triton pattern is clearly visible and its wide energy spread in both directions is due to variable energy loss in the target, depending on the emission depth and angle, and to the spread of incidence angles on the detector.…”

Section: The Validation Testmentioning

confidence: 99%

“…The still higher neutron flux of about 10 7 ÷10 8 n/cm 2 /s, obtained with the reduced flight path of 19 m with respect to the 185 m of the older EAR1, allows to perform experiments on low-mass targets and/or targets made out of short-lived radionuclides, even on isotopes characterized by a small reaction cross-section, with a favorable signal to background ratio. Indeed, challenging measurements of reactions with outgoing charged particles have now become attainable [1][2] [3].…”

Section: Introductionmentioning

confidence: 99%

Experimental setup and procedure for the measurement of the 7Be(n,p)7Li reaction at n_TOF

Barbagallo

Andrzejewski

Mastromarco

et al. 2018

Nuclear Instruments and Methods in Physics Research Section A:

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Following the completion of the second neutron beam line and the related experimental area (EAR2) at the n_TOF spallation neutron source at CERN, several experiments were planned and performed. The high instantaneous neutron flux available in EAR2 allows to investigate neutron indiced reactions with charged particles in the exit channel even employing targets made out of small amounts of short-lived radioactive isotopes. After the successful measurement of the 7 Be(n,α)α cross section, the 7 Be(n,p) 7 Li reaction was studied in order to provide still missing cross section data of relevance for Big Bang Nucleosynthesis (BBN), in an attempt to find a solution to the cosmological Lithium abundance problem. This paper describes the experimental setup employed in such a measurement and its characterization.

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