Neutron beam line for TOF measurements at the Spanish National Accelerator Lab (CNA)

Miguel Macías,Begoña Fernández,Javier Praena

doi:10.1051/epjconf/202023917014

Abstract

A few years ago, the Spanish National Accelerator Lab (CNA) developed the first accelerator-based neutron facility in Spain called HiSPANoS (HiSPAlis Neutron Source). The first applications of the line were related to integral measurements applied to nuclear astrophysics, dosimetry and single event effects produced by neutrons in electronic devices. The successful of HiSPANoS pushed the enhancement of the facility. In collaboration with the NEC® Company, two devices were designed for pulsing ion beams (Chopper) and for compressing in time (Buncher) the pulsed beams. The Chopper-Buncher system has been already installed and commissioned. Proton and deuteron beams are delivered with repetition rates from 62.5 kHz to 2 MHz and 1 ns pulse width. In addition, a new line of the 3 MV Tandem Pelletron accelerator was designed for neutron time-of-flight (TOF) experiments. Conventional devices and a dedicated Pick-Up for timing measurements form the new line. In order to check the performance of the whole TOF system, we have carried out the measurement of the neutron spectrum produced by 7Li(p,n)7Be reaction at Ep = 1912 keV. Such spectrum has been measured by the TOF technique few times and it can be considered a standard neutron field, in particular in nuclear astrophysics. The first result of such experiment performed at CNA is shown in some detail. The excellent performance of the accelerator, the Chopper-Buncher system and the acquisition system allow us to offer the TOF line at HiSPANoS-CNA to the neutron community.

Highlights

HiSPANoS is a facility which uses ion beams, provided by an accelerator, and nuclear reactions in order to generate neutrons
Accelerator-Based Neutron Sources (ABNS) is relevant for neutron science in basic physics research, and play a significant role in a variety of applications, such as material science, education, medicine and is an industrial driver of the engineering
The ions can be produced by three NEC R sources: the Alphatross, which generates ions from gases using radio frequency techniques; the Duoplasmatron, in which the ions are produced by bombarding the atoms of a chosen gas with electrons; and the SNICS II, a cesium sputtering source that produces ions from solid samples

Summary

Introduction

HiSPANoS is a facility which uses ion beams, provided by an accelerator, and nuclear reactions in order to generate neutrons. The 7Li(p,n)7Be reaction has been used for producing different stellar neutron beams for nuclear astrophysics studies [3][4]. A new experimental line has been designed and mounted after the 90◦ magnet in the same direction as the accelerator tank, as shown in the scheme of Figure 1. Where ∆l/l and ∆t/t are the fractional uncertainties in the measurement of the length of the flight path and of time respectively

Pulsed system

Neutron TOF line

Pulsed system testing

Commissioning