¹⁶O(n,α) cross section investigation using LENZ instrument at LANSCE

Abstract

Abstract. Importance of studying the 16 O(n,α) reaction is motivated by multiple nuclear applications. The Los Alamos Neutron Science Center (LANSCE) produces a white neutron spectrum ranging from thermal to several hundreds of MeV energies. We have recently developed the LENZ (Low Energy NZ-neutron induced charged particle detection) capability to measure high-precision (n,α) cross sections. In order to provide more reliable data, we have enhanced solid angle coverage, and improved signal-to-noise ratios and time-of-flight resolution by implementing digitizer waveform analysis. The LENZ was commissioned by studying the 59 Co(n,α) reaction with neutron beams in early 2015. For the 16 O(n,α) reaction, we investigate solid oxygen targets and make a relative measurement to a better known cross section, such as the 6 Li(n,α) reaction in order to further reduce systematic uncertainty. We will discuss the progress of the 16 O(n,α) study at LANSCE and the outlook for improving Hauser-Feshbah prediction on (n,p) reaction cross sections.

Templates of expected measurement uncertainties for neutron-induced capture and charged-particle production cross section observables

“…In the case of charged-particle production reactions, the charged product can be measured directly at the time of the reaction. Gaseous detectors such as proportional counters [85], gridded ionization chambers [86][87][88] and compensated ionization chambers [89,90] can provide large solid-angle coverage and high intrinsic detection efficiencies. Solid state detectors such as silicon surface barrier detectors [4,91,92] and single crystal diamond detectors [93,94] allow for good energy and angle resolution and are less sensitive to γ rays.…”

“…Scintillation detectors such as Li glass [95,96], ZnS [89], and CsI(Tl) [97] have fast timing resolution and high intrinsic detection efficiencies. Multiple detector types are often combined to take advantage of the differing strengths, such as the LENZ detector system at LANSCE [86] (Frisch grid ionization chambers and silicon strip detectors), the FAZIA collaboration [97] (silicon strip detectors and CsI(Tl) detectors), and the LPDA detector system at the CSNS Back-n facility [98] (silicon detector array and Frisch grid ionization chamber). A simple schematic of the measurement is shown in Figure 3d.…”

Neutron-Induced Charged Particle Measurements at LANSCE in the Interest of P-Process Nucleosynthesis

“…Energy calibration was performed using a 229 Th source in DSSDs (1000 micron and 1500 micron thick detectors) using CAEN digitizers [9] and was estim ated to be about 50 keV energy resolution [10]. Various digital filters like exponential decay fit, trapezoidal filter, charge integration, are applied to investigate the best timing and energy resolutions with stored waveforms.…”

Research Essay for the Goldwater Scholarship Application

“…Oxygen is found in many natural and human-made structures and materials, including water, concrete, or any oxide. The severe lack of data on the cross section of 16 O(n,α), a reaction that can be found in any material containing oxygen, is detrimental to a complete understanding of the natural or induced behavior of these materials [HYL16]. Additionally, study of this particular reaction and other neutron-induced reactions involving oxygen are useful in the design of naval light water reactors and applications in radio-biology [HYL16].…”

“…The severe lack of data on the cross section of 16 O(n,α), a reaction that can be found in any material containing oxygen, is detrimental to a complete understanding of the natural or induced behavior of these materials [HYL16]. Additionally, study of this particular reaction and other neutron-induced reactions involving oxygen are useful in the design of naval light water reactors and applications in radio-biology [HYL16]. A detailed understanding of the 16 O(n,α) reaction is vital to the safe and efficient study, design, and development of applications such as these.…”