1 #include "isajet/pilot.h"
3 C***********************************************************************
4 C* Computes the electron spectrum as a convolution of the beam- and *
5 C* bremsstrahlung-spectra, including leading-log summation for the lat-*
6 C* ter (in one-loop order), and Chen's approximate expression for the *
7 C* former. X is the e energy in units of the nominal beam energy, and *
8 C* BETA is 2 alpha_em / pi (log s/me^2 - 1). If more than 99.5% of all *
9 C* electrons are in the delta-peak, beamstrahlung is ignored. Other- *
10 C* wise, beamstrahlung is included. In the latter case, the complete *
11 C* spectrum is computed at the first call (with INIT=1), and fitted in *
12 C* a cubic spline; in later calls (with INIT=0), only the spline is *
13 C* used. This reduces the necessary amount of CPU time considerably. *
14 C* This subroutine needs the programs BEAMEL, SIMAU8, and SPLINE. *
15 C***********************************************************************
16 #if defined(CERNLIB_IMPNONE)
19 #include "isajet/eepar.inc"
20 #include "isajet/brembm.inc"
24 REAL Y,XLMM,XL,GAM,RE,XKAPPA,NUCL,NUGAM,NGAM,DC,
25 $DX,TAU(100),C(4,100),XM,Z,RES,SSXINT,Y2,H,S,ESTRUC,Y1
31 C Compute delta function contribution
34 XLMM = 2*SQRT(3.)*XLMM
35 XL = XLMM*1.E12/.197327
37 RE = 1./(137.*5.11E-4)
39 NUCL = 2.5*Y/(SQRT(3.)*137.**2*GAM*RE)
40 NUGAM = NUCL/SQRT(1.+Y**.6666666)
42 DC = (1.-EXP(-NGAM))/NGAM
44 C No initialization needed if >.995 included in delta peak
47 C *** Computation of 'knots' ***
51 100 TAU(I) = FLOAT(I-1)*DX
53 110 TAU(19+I) = .9 + FLOAT(I)*1.E-2
55 120 TAU(28+I) = .99 + FLOAT(I)*1.E-3
57 121 TAU(33+I) = .995 + FLOAT(I)*2.5E-4
59 130 TAU(45+I) = .998 + FLOAT(I)*1.E-4
61 C *** Computation of corresponding y-values (electron densities) ***
67 RES=SSXINT(Z,FBRBM,XM)
68 140 C(1,I) = RES +DC*ESTRUC(Z,QSQBM)
70 C *** Computation of derivative at zero ***
74 RES=SSXINT(Z,FBRBM,XM)
75 Y1 = RES + DC*ESTRUC(Z,QSQBM)
78 RES=SSXINT(Z,FBRBM,XM)
79 Y2 = RES + DC*ESTRUC(Z,QSQBM)
80 C(1,2) = (Y2-Y1)/(1.E-4 - 1.E-5)
81 147 CALL SPLINE(TAU,C,65,1,0)
89 DC = (1.-EXP(-NGAM))/NGAM
91 SSFEL = DC*ESTRUC(Z,QSQBM)
96 2 IF(Z.LT.TAU(I+1)) GOTO 3
98 S = C(1,I) + H * ( C(2,I) + H*(C(3,I)+H*C(4,I)) )