NEA-0700 NRESP4.

1. NAME OR DESIGNATION OF PROGRAM:  NRESP4.

3. DESCRIPTION OF PROBLEM OR FUNCTION

The programs calculate response functions of an organic scintillation detector for incident neutrons in the energy range from 0.05 to 20.0 MeV. The detector system consists of a cylindrical scintillator (e.g. NE213) surrounded by a  cylindrical aluminium housing and connected to a lucite light pipe.

4. METHOD OF SOLUTION

The codes use the Monte Carlo method. Histories of neutrons emitted from a source positioned outside the scinillator are calculated. The spectrum of the light output from secondary charged particles produced by neutron reactions within the scintillator is calculated.

5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM

A neutron point source positioned at the scintillator axis at any distance from the  scintillaor or for larger distances with an angle from 0 to 90 degrees off this axis are considered. Cross section data for H, C, and Al up to 20 MeV are taken from ENDF/B-V. Non isotropic angular distributions are included for elastic and inelastic scattering from Al. Point cross sections are used with interpolation intervals of 20 to 100 keV. Wall effects are considered only for protons.

6. TYPICAL RUNNING TIME

NRESP4: To calculate a response spectrum with 200,000 neutron histories takes about 25 minutes on the TR440.
NEFF4: To calculate the detector efficiency from 0 to 20 MeV with an energy bin of 100 keV and 3,000,000 neutron histories takes about 9 hours on the TR440.

NEA-DB executed the test cases included in the package  on a VAX-11/780. NRESP4 required 31 CPU seconds; NEFF4 required 40 seconds of CPU running time.

7. UNUSUAL FEATURES OF THE PROGRAM

The Monte Carlo code uses weighting methods and may therefore also be applied to small scintillators. Neutron scattering in the surrounding aluminium housing and in the light pipe is taken into account. The programs use new cross section data and up to 7 channels for the 12(n,n'3alpha) reaction.

8. RELATED AND AUXILIARY PROGRAMS

NRESP4 calculates the response function with a non-linear bin width. The program NTRANS transforms  this spectrum to a spectrum which is linear in light output. The spectrum may also be folded with a channel-dependent detector resolution.

10. REFERENCES:

- G. Dietze and H. Klein:
  NRESP4 and NEFF4: Monte Carlo Codes for the Calculation of Neutron
  Response Functions and Detection Efficiencies for NE 213
  Scintillation Detectors.  PTB-ND-22  (October 1982)

11. MACHINE REQUIREMENTS

The programs run in 45K bytes of main storage on TR440. A external data storage device is needed for input and output.

Main storage requirements for test case execution are:  105,960 bytes (NRESP4); 94,208 bytes (NEFF4); 15,360 bytes 9NTRANS).

13. OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED:
BS 3, MV 192617 time sharing system of TR440.

VAX/VMS V3.4 (VAX-11/780).

14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS:

15. NAME AND ESTABLISHMENT OF AUTHORS

    Guenther Dietze:
    Physikalisch-Technische Bundesanstalt
    Bundesallee 100
    D-3300 Braunschweig
    Federal Republic of Germany

File name	File description	Records
NEA0700_02.003	INFORMATION FILE	80
NEA0700_02.004	NRESP4 FORTRAN SOURCE	1938
NEA0700_02.005	NRESP4 COMMAND PROCEDURE FOR SAMPLE CASE	33
NEA0700_02.006	NRESP4 SAMPLE CASE	6
NEA0700_02.007	NRESP4 SAMPLE CASE PRINTED OUTPUT	64
NEA0700_02.008	NRESP4 SPECTRUM OUTPUT(UNIT 41)	161
NEA0700_02.009	NEFF4 FORTRAN SOURCE	1808
NEA0700_02.010	NEFF4 COMMAND PROCEDURE FOR SAMPLE CASE	33
NEA0700_02.011	NEFF4 SAMPLE CASE INPUT	8
NEA0700_02.012	NEFF4 SAMPLE CASE PRINTED OUTPUT	85
NEA0700_02.013	NEFF4 SPECTRUM OUTPUT (LOGICAL UNIT 41)	56
NEA0700_02.014	NWQ4 DATA LIBRARY IN SEQUENTIAL	1537
NEA0700_02.015	AUXILIARY PROGRAM TO CONVERT NWQ4 LIBRARY	28
NEA0700_02.016	NTRANS FORTRAN SOURCE	163