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PSR-0101 HYPERMET/A1.

HYPERMET, Ge(Li) Detector Multichannel Analyser Gamma Spectra Evaluation

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1. NAME OR DESIGNATION OF PROGRAM:  HYPERMET/A1.
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2. COMPUTERS
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Program name Package id Status Status date
HYPERMET-2.7 PSR-0101/02 Tested 04-JUN-1985
HYPERMET PSR-0101/03 Arrived 04-DEC-2001

Machines used:

Package ID Orig. computer Test computer
PSR-0101/02 CDC 3800 CDC CYBER 74
PSR-0101/03 FACOM M-190
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3. DESCRIPTION OF PROBLEM OR FUNCTION

HYPERMET is used to perform an  automatic analysis of a multichannel gamma-ray pulse-height spectrum taken with a germanium detector. The spectrum is searched for peaks  within a specified region. When found, a subregion is defined about  each peak or group of peaks and a non-linear least-squares fit is performed to a parameterized peak shape plus background using an iterative variable-metric technique to search for the best values of the parameters.

When all regions have been searched a final table is printed of the position, width, area, and count rate (and the standard deviation of each) for all peaks found in all regions of the spectrum. Any regions where chisquare exceeds an upper limit, standard deviations will be flagged in the final table by a minus sign in front of the region number.

A number of options are available including an energy calibration, correction for radioactive decay, and a CALCOMP plot of each fit.
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4. METHOD OF SOLUTION

First a peak search is made to determine the locations of any peaks within the specified region. The search is completely automatic with a high probability of finding all true peaks while discriminating against statistical fluctuations, Compton edges, and other spurious or non-peak features of the spectrum. When a peak is found, a search is made for any additional close-lying peaks which could distort the fit if not included. A fitting sub-region is then defined about the peak or peaks. Within this sub- region initial estimates are made for the parameters such as back- ground level, slope and curvature, peak height above background, peak tailing parameters, etc. to use as starting values for the fit. A semi-empirical parameterized peak shape function has been developed to be both complete enough and flexible enough to give a satisfactory fit to the variety of peak shapes, sometimes overlapping.

An iterative non-linear least squares fit is then performed for optimum values of the peak shape and background parameters using an  improved variable-metric fitting routine by Fletcher (4). If a good  fit is obtained, the final parameters and resultant fit are printed  out. If not a good fit, attempts are made to improve the fit; the residuals are searched for the largest statistically weighted value  of data minus fit, and a new fit is made with an additional peak at  the position of the largest residual. In this way even very weak but statistically significant peaks on the shoulder of a strong peak are detected and analyzed.
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5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM:  A maximum of 8196 channels may be analyzed.
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6. TYPICAL RUNNING TIME:
PSR-0101/02
NEA-DB executed the test case included in the package on CDC CYBER 740 in 130 seconds of CPU time.
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7. UNUSUAL FEATURES OF THE PROGRAM:
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8. RELATED AND AUXILIARY PROGRAMS:
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9. STATUS
Package ID Status date Status
PSR-0101/02 04-JUN-1985 Tested at NEADB
PSR-0101/03 04-DEC-2001 Masterfiled Arrived
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10. REFERENCES:
- R. Fletcher:, Computer Journal vol 13 p.317 (1970)
PSR-0101/02, included references:
- G.W. Phillips:
  Guide to HYPERMET Version 2.7 .  (August 1976)
- G.W. Phillips and K.W. Marlow:
  Program HYPERMET for Automatic Analysis of Gamma-Ray Spectra from
  Germanium Detectors.  NRL Memorandum Report 3198  (January 1976)
PSR-0101/03, included references:
- G.W. Phillips and K.W. Marlow:
  Program HYPERMET for Automatic Analysis of Gamma-Ray Spectra from
  Germanium Detectors.  NRL Memorandum Report 3198  (January 1976)
- G.W. Phillips:
  Guide to Program HYPERMET Version A.1.   (February 1977)
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11. MACHINE REQUIREMENTS

Except for a few system input-output routines program HYPERMET will fit into one 32k word bank on a CDC 3800.
PSR-0101/02
131,300 (octal) words of main storage on CDC CYBER 740.
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12. PROGRAMMING LANGUAGE(S) USED
Package ID Computer language
PSR-0101/02 FORTRAN-IV
PSR-0101/03 FORTRAN-IV
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13. OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED:
PSR-0101/02
NOS 1.4-531 (CDC CYBER 740).
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14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS:
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15. NAME AND ESTABLISHMENT OF AUTHOR

G.W. Phillips
Radiation Technology Division
Naval Research Laboratory
Washington D.C. 20375, U.S.A.
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16. MATERIAL AVAILABLE
PSR-0101/03
source program   mag tapeHYPERMET Source                       SRCTP
report                   NRL Memorandum Report 3198  (January 1976) REPPT
report                   Guide to HYPERMET  (February 1977)         REPPT
PSR-0101/02
File name File description Records
PSR0101_02.003 INFORMATION FILE 72
PSR0101_02.004 JCL TO EXECUTE TEST CASE 20
PSR0101_02.005 HYPERMET SOURCE PROGRAM 4026
PSR0101_02.006 FLETCHER SOURCE PROGRAM 45
PSR0101_02.007 HYPERMET TEST CASE INPUT DATA 7
PSR0101_02.008 CALIBRATION RUN 301 513
PSR0101_02.009 HYPERMET TEST CASE PRINTED OUTPUT 2655
PSR0101_02.010 CALIBRATION RUN IN CANBERRA FORMAT 1
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17. CATEGORIES
  • O. Experimental Data Processing

Keywords: Li-drifted ge detectors, gamma detectors, gamma spectra, least square fit, multi-channel analysers, spectra unfolding.