Neutron-induced reactions in the high-density plasma of a DT capsule implosion at the National Ignition Facility: calibration measurementsR


  Rudra N. Sahoo  ,  M. Paul  ,  M. Tessler  ,  M. L. Avila  ,  C. Dickerson  ,  H. Jayatissa  ,  J. McLain  ,  R.C. Pardo  ,  K. E. Rehm  ,  R. Scott  ,  I. Toltsukhin  ,  R. Vondrasek  ,  C. Velsko  ,  A. Zylstra  ,  T. Bailey  ,  L. Callahan  ,  A. Clark  ,  Y. Kashiv  ,  A. Nelson  ,  P. Collon  ,  U. Köster  ,  K. Zuber  ,  R. Schwengner  
The Hebrew University of Jerusalem, Israel
Soreq Nuclear Research Center, Yavneh, Israel
Argonne National Laboratory, Argonne, IL, USA
Lawrence Livermore National Laboratory, Livermore, CA, USA
University of Notre Dame, Notre Dame, IN, USA
Institut Laue-Langevin, Grenoble, France
Technical University Dresden, Dresden, Germany
Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany

Neutron-induced reactions in the high-density plasma of a DT capsule implosion at the National Ignition Facility: calibration measurements

R. N. Sahoo1, M. Paul1, M. Tessler2, M. L. Avila3, C. Dickerson3, H. Jayatissa3, J. McLain3, R.C. Pardo3,
K. E. Rehm3, R. Scott3, I. Toltsukhin3, R. Vondrasek3, C. Velsko4, A. Zylstra4, T. Bailey5,
L. Callahan5, A. Clark5, Y. Kashiv5, A. Nelson5, P. Collon5, U. Köster6, K. Zuber7, R. Schwengner8

1 The Hebrew University of Jerusalem, Israel
2 Soreq Nuclear Research Center, Yavneh, Israel
3 Argonne National Laboratory, Argonne, IL, USA
4 Lawrence Livermore National Laboratory, Livermore, CA, USA
5 University of Notre Dame, Notre Dame, IN, USA
6 Institut Laue-Langevin, Grenoble, France
7 Technical University Dresden, Dresden, Germany
8 Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany

The thermodynamical conditions of plasma density, temperature, pressure and the neutron density produced in a laser-induced implosion of a DT-filled capsule at the National Ignition Facility (NIF) are the closest laboratory analog to stellar conditions.  In a NIF high-power laser shot approved and scheduled for Fall 2022, we plan to study neutron-induced reactions on 40Ar incorporated in the capsule gas.  We will investigate two neutron-induced reactions on 40Ar, namely 40Ar(n,2n)39Ar and 40Ar(2n,γ)42Ar by counting atoms of long-lived 39Ar (268 y) and 42Ar (33 y)  nuclides produced in the same shot. The former reaction product is a direct monitor of the fast-neutron flux, the latter is a monitor of extreme neutron densities in conditions approaching those of the stellar r process. The chemical inertness of the noble gas Ar allows for reliable collection of reaction products. The ultra-sensitive technique of accelerator mass spectrometry is planned to be used for yield determination.  We report here on calibration measurements of the yield of the 40Ar(n,2n)39gAr reaction in a 14 MeV neutron activation, investigated for the first time. The neutron activation was performed with the DT neutron generator of Technical University Dresden located at Helmholtz-Zentrum Dresden-Rossendorf. Direct identification detection of the 42Ar nuclide was successfully demonstrated for the first time in a 40Ar sample activated by the slow double-neutron capture reaction 40Ar(n,γ)41Ar(n,γ)42Ar for 8 days at the high-flux reactor of Institut Laue-Langevin.  We performed the detection of both 39Ar and 42Ar reaction products using noble-gas accelerator mass spectrometry (NOGAMS) at the ATLAS accelerator facility (Argonne National Laboratory). Preliminary results of these calibration experiments are presented.
This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357.   This research used resources of ANL’s ATLAS facility, which is a DOE Office of Science User Facility. Partial support from the Pazi Foundation (Israel) and USA-Israel Binational Foundation is gratefully acknowledged.