ADAS Subroutine qhe

       FUNCTION QHE(EPRO,TTAR,ISEL,ZSEL,NSEL,IORD,EA,OA,N,IPASS,
     &              DSLPATH)
C
       IMPLICIT REAL*8(A-H,O-Z)
C
C-----------------------------------------------------------------------
C
C  ****************** FORTRAN77 FUNCTION: QHE ***************************
C
C  PURPOSE : TO EVALUATE MAXWELL AVERAGED TOTAL IONISATION, EXCITATION
C	     AND CHARGE EXCHANGE RATE COEFFICIENTS. FUNCTION ALSO
C	     RETURNS THE RAW CROSS SECTION DATA FOR VERIFICATION AND
C	     GRAPHING PURPOSES.
C            THE INCIDENT PARTICLE IS A MONOENERGETIC
C	     BEAM AND THE TARGET IS A MAXWELL DISTRIBUTION. THE TARGET AND
C	     PROJECTILE ROLES MAY BE REVERSED. ARBITRARY RELATIVE SPEEDS
C            ARE ALLOWED.
C
C  HISTORY : ROUTINE WAS ORIGINALLY WRITTEN BY H.P.SUMMERS AND MODIFIED
C	     AND RESTRUCTURED BY HARVEY ANDERSON.	
C
C  DATA   :  ROUTINE UTILISES THE ION/ATOM COLLISION DATABASE ASSEMBLED FOR
C	     HELIUM IN INTERACTION WITH IMPURITIES UPTO THE SECOND
C	     PERIOD. THE DATA BASE IS OF ADAS ADF02 TYPE FORMAT :
C
C		/ADAS/ADF02/SIA#HE/SIA#HE_J91#HE.DAT
C
C  INPUT  :
C
C	     (R*8)	EPRO	:	INCIDENT PARTICLE ENERGY (EV/AMU).
C	     (R*8)	TTAR	:	MAXWELL TEMPERATURE OF TARGET
C					PARTICLES (EV) IF (TTAR.LE.0) THEN
C					ONLY RAW SOURCE VALUES ARE RETURNED
C              				IN ARRAYS (EA(I),OA(I), I=1,N).
C	     (R*8)      ZSEL	:	NUCLEAR CHARGE (REQUIRED ONLY FOR
C					PARTICULAR ISEL).
C	     (I*4)	ISEL	:	SELECTOR FOR PARTICULAR RATE COEFFT.
C					CHOSEN FROM TABLE BELOW (SEE ALSO
C					NOTES ON DATA).
C	     (I*4)	NSEL	:	PRINC. QUANTUM NO. (REQUIRED ONLY FOR
C					PARTICULAR ISEL NB. NSEL SHOULD BE
C					ZERO ON ENTRY OTHERWISE).
C	     (I*4)      IORD    :	1 FOR 1ST PARTICLE INCIDENT AND
C					MONOENERGETIC = 2 FOR 2ND PARTICLE
C					INCIDENT AND MONOENERGETIC.
C	     (I*4)	IPASS	:	0 IF DATA FILE TO BE READ IN AFRESH
C            				1 IF DATA FILE IS NOT TO BE READ IN
C					AGAIN.
C	
C
C  OUTPUT :
C      	     (R*8)	QHE     :	RATE COEFFICIENT (CM3 SEC-1).
C            (R*8)      EA	: 	SET OF ENERGIES (EV/AMU) FOR SELECTED
C					SOURCE DATA.
C            (R*8)      OA      :       CROSS-SECTIONS (CM**2) FOR SELECTED
C					SOURCE DATA.
C      	     (I*4)      N       :       NUMBER OF SOURCE DATA VALUES
C      	     (CHR)	TITLF   :	INFORMATION STRING.
C
C
C
C  CONTACT : HARVEY ANDERSON
C	     UNIVERSITY OF STRATHCLYDE.
C	     ANDERSON@CHAMBA.PHYS.STRATH.AC.UK
C
C  DATE    : 05/10/97
C
C
C VERSION: 1.2                          DATE: 15-10-99
C MODIFIED: RICHARD MARTIN
C  		REMOVED 'ACTION' FROM OPEN STATEMENT.
C
C VERSION: 1.3				DATE: 07-07-2004
C MODIFIED: ALLAN WHITEFORD
C 		-CHANGED CALLS FROM DXNB{A,B}F TO XXNB{A,B}F
C
C----------------------------------------------------------------------
      CHARACTER*80        DSLPATH
      INTEGER             IORD,        IPASS,       ISEL,        N
      INTEGER             NSEL
      REAL*8              EA(24),      EPRO,        OA(24),      TTAR
      REAL*8              ZSEL