source: trunk/MagicSoft/Simulation/Corsika/Mmcs/nkg.f@ 18679

Last change on this file since 18679 was 286, checked in by harald, 25 years ago
This is the start point for further developments of the Magic Monte Carlo Simulation written by Jose Carlos Gonzales. Now it is under control of one CVS repository for the whole collaboration. Everyone should use this CVS repository for further developments.
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1 SUBROUTINE NKG( ENERN )
2
3C-----------------------------------------------------------------------
4C N(ISHIMURA) K(AMATA) G(REISEN)
5C
6C CALCULATES ELECTROMAGNETIC COMPONENT OF SHOWERS USING THE ANALYTIC
7C NKG FORMULAS, INCLUDING ELECTRON ENERGY THRESHOLD ELCUT(3)
8C SEE J.N. CAPDEVIELLE, 22ND ICRC, DUBLIN 1991, CONTRIB. HE 3.5.10
9C THIS SUBROUTINE IS CALLED FROM EM
10C ARGUMENTS:
11C ENERN = ENERGY OF ELECTRON/PHOTON GENERATING A SUBSHOWER
12C NEGATIVE FOR SUBSHOWERS TO BE SUBTRACTED AFTER
13C PHOTONUCLEAR REACTION
14C-----------------------------------------------------------------------
15
16 IMPLICIT NONE
17*KEEP,CONST.
18 COMMON /CONST/ PI,PI2,OB3,TB3,ENEPER
19 DOUBLE PRECISION PI,PI2,OB3,TB3,ENEPER
20*KEEP,ELABCT.
21 COMMON /ELABCT/ ELCUT
22 DOUBLE PRECISION ELCUT(4)
23*KEEP,NKGI.
24 COMMON /NKGI/ SEL,SELLG,STH,ZEL,ZELLG,ZSL,DIST,
25 * DISX,DISY,DISXY,DISYX,DLAX,DLAY,DLAXY,DLAYX,
26 * OBSATI,RADNKG,RMOL,TLEV,TLEVCM,IALT
27 DOUBLE PRECISION SEL(10),SELLG(10),STH(10),ZEL(10),ZELLG(10),
28 * ZSL(10),DIST(10),
29 * DISX(-10:10),DISY(-10:10),
30 * DISXY(-10:10,2),DISYX(-10:10,2),
31 * DLAX (-10:10,2),DLAY (-10:10,2),
32 * DLAXY(-10:10,2),DLAYX(-10:10,2),
33 * OBSATI(2),RADNKG,RMOL(2),TLEV(10),TLEVCM(10)
34 INTEGER IALT(2)
35*KEEP,NKGS.
36 COMMON /NKGS/ CZX,CZY,CZXY,CZYX,SAH,SL,ZNE
37 DOUBLE PRECISION CZX(-10:10,2),CZY(-10:10,2),CZXY(-10:10,2),
38 * CZYX(-10:10,2),SAH(10),SL(10),ZNE(10)
39*KEEP,OBSPAR.
40 COMMON /OBSPAR/ OBSLEV,THCKOB,XOFF,YOFF,THETAP,PHIP,
41 * THETPR,PHIPR,NOBSLV
42 DOUBLE PRECISION OBSLEV(10),THCKOB(10),XOFF(10),YOFF(10),
43 * THETAP,THETPR(2),PHIP,PHIPR(2)
44 INTEGER NOBSLV
45*KEEP,PARPAR.
46 COMMON /PARPAR/ CURPAR,SECPAR,PRMPAR,OUTPAR,C,
47 * E00,E00PN,PTOT0,PTOT0N,THICKH,ITYPE,LEVL
48 DOUBLE PRECISION CURPAR(14),SECPAR(14),PRMPAR(14),OUTPAR(14),
49 * C(50),E00,E00PN,PTOT0,PTOT0N,THICKH
50 INTEGER ITYPE,LEVL
51*KEEP,PARPAE.
52 DOUBLE PRECISION GAMMA,COSTHE,PHI,H,T,X,Y,CHI,BETA,GCM,ECM
53 EQUIVALENCE (CURPAR(2),GAMMA), (CURPAR(3),COSTHE),
54 * (CURPAR(4), PHI ), (CURPAR(5), H ),
55 * (CURPAR(6), T ), (CURPAR(7), X ),
56 * (CURPAR(8), Y ), (CURPAR(9), CHI ),
57 * (CURPAR(10),BETA), (CURPAR(11),GCM ),
58 * (CURPAR(12),ECM )
59*KEEP,RUNPAR.
60 COMMON /RUNPAR/ FIXHEI,THICK0,HILOECM,HILOELB,
61 * STEPFC,NRRUN,NSHOW,PATAPE,MONIIN,
62 * MONIOU,MDEBUG,NUCNUC,
63 * CETAPE,
64 * SHOWNO,ISHW,NOPART,NRECS,NBLKS,MAXPRT,NDEBDL,
65 * N1STTR,MDBASE,
66 * DEBDEL,DEBUG,FDECAY,FEGS,FIRSTI,FIXINC,FIXTAR,
67 * FIX1I,FMUADD,FNKG,FPRINT,FDBASE
68 * ,GHEISH,GHESIG
69 COMMON /RUNPAC/ DSN,HOST,USER
70 DOUBLE PRECISION FIXHEI,THICK0,HILOECM,HILOELB
71 REAL STEPFC
72 INTEGER NRRUN,NSHOW,PATAPE,MONIIN,MONIOU,MDEBUG,NUCNUC,
73 * SHOWNO,ISHW,NOPART,NRECS,NBLKS,MAXPRT,NDEBDL,
74 * N1STTR,MDBASE
75 INTEGER CETAPE
76 CHARACTER*79 DSN
77 CHARACTER*20 HOST,USER
78
79 LOGICAL DEBDEL,DEBUG,FDECAY,FEGS,FIRSTI,FIXINC,FIXTAR,
80 * FIX1I,FMUADD,FNKG,FPRINT,FDBASE
81 * ,GHEISH,GHESIG
82*KEND.
83
84 DOUBLE PRECISION AE,AS,ASE,AUXIL,BS,CCP,CPC,CPCP,CPH,CSGA,
85 * DE,DISTL,ECRI,ECR1,ECR2,ENERN,GAM,GRCUT,
86 * G1,G2,G3,S,SC1,SC2,SIGNE,SM,SMRM,
87 * SQRZ1I,SQZC1I,SQZC2I,SS2,SS45,TEX,THICK,THICKP,
88 * XMOL,XNE,XS,X0,YM,YS,ZC1,ZC2,ZG1,ZG2,ZG3,Z1
89 INTEGER IL,IOL,M
90 EXTERNAL GAM,THICK
91C X0 IS RADIATON LENGTH IN AIR (G/CM**2)
92C (SEE ALSO MIKOCKI ET AL. J.PHYS.G.:NUCL.PART.PHYS. 17 (1991) 1303 )
93C GRCUT IS GREISEN CUT OFF, ECRI IS CRITICAL ENERGY IN AIR
94C ECR2 IS 0.4 * ECRI
95 DATA X0 / 37.1D0 /, GRCUT / 0.1D0 /, ECRI / 0.082D0 /
96 DATA ECR2 / 0.0328D0 /
97C-----------------------------------------------------------------------
98
99 IF (DEBUG) WRITE(MDEBUG,*)'NKG : ',SNGL(SECPAR(1)),SNGL(ENERN)
100
101C CHECK WETHER SUBSHOWER IS SUBTRACTED
102 IF ( ENERN .GE. 0.D0 ) THEN
103 SIGNE = +1.D0
104 ELSE
105 ENERN = -ENERN
106 SIGNE = -1.D0
107 ENDIF
108
109C ENERGY CUT OFF IN GREISEN FORMULA
110C (EM PARTICLE BELOW THIS CUT CAN NOT PRODUCE A SHOWER)
111 IF ( ENERN .LT. GRCUT ) RETURN
112C DON'T CALCULATE NKG FOR BACKWARD GOING PARTICLES
113 IF ( SECPAR(3) .LE. 0.D0 ) RETURN
114C DON'T CALCULATE NKG IF PARTICLE BELOW THE LOWEST OBSERVATION LEVEL
115 IF ( SECPAR(5) .LT. OBSATI(1) ) RETURN
116
117 Z1 = LOG(ENERN / ECRI)
118 SQRZ1I = 1.D0 / SQRT(Z1)
119
120C THIS CUT IS ONLY IMPORTANT FOR ELCUT > .0672
121 ECR1 = ECR2 + ELCUT(3)
122 IF ( ENERN .LT. ECR1 ) RETURN
123 ZC1 = LOG(ENERN / ECR1)
124 SQZC1I = 1.D0 / SQRT(ZC1)
125C LOG(ENERN/ECR2) IS LOG(ENERN / ECRI) - LOG(0.4)
126 ZC2 = Z1 + 0.916290732D0
127 SQZC2I = 1.D0 / SQRT(ZC2)
128 THICKP = THICK(SECPAR(5))
129
130C LOOP OVER LEVELS
131 DO 14 IL = 1,IALT(1)
132C DISREGARD LEVELS ABOVE THE PARTICLE
133 IF ( TLEVCM(IL) .GT. SECPAR(5) ) GOTO 14
134C DISTANCE IN G/CM**2 .... (ALONG PHOTON-AXIS) IN RADIATION LENGTHS
135 XMOL = (TLEV(IL) - THICKP) / ( X0 * SECPAR(3) )
136C CORRECT DEPTH FOR SUBSHOWERS TO BE SUBTRACTED BY 9/7
137 IF ( SIGNE .LT. 0.D0 ) XMOL = XMOL + 1.285714286D0
138C XMOL IS DEPTH IN RADIATION LENGTHS
139 IF ( XMOL .GT. 60.D0 .OR. XMOL .LT. 1.D0 ) GOTO 14
140C S IS AGE PARAMETER
141 S = 3.D0 * XMOL / (XMOL + 2.D0 * Z1)
142 IF ( S .LE. 0.2D0 ) GOTO 14
143 SC1 = 3.D0 * XMOL / (XMOL + 2.D0 * ZC1)
144 SC2 = 3.D0 * XMOL / (XMOL + 2.D0 * ZC2)
145C ELECTRON NUMBER AT OBSERVATION LEVEL
146 CPH = .31D0 * EXP( XMOL * (1.D0 - 1.5D0 * LOG(S) ) ) * SQRZ1I
147 CPC = EXP( XMOL * ( 1.D0 - 1.5D0 * LOG(SC1) ) ) * SQZC1I
148 CCP = EXP( XMOL * ( 1.D0 - 1.5D0 * LOG(SC2) ) ) * SQZC2I
149 CPCP = SIGNE * CPH * CPC / CCP
150C INTERMEDIATE FACTORS FOR LATERAL DISTRIBUTION AND AGE PARAMETER
151 AE = 4.D0 * EXP( 0.915D0 * (S - 1.D0) ) / S
152 DE = ( 1.D0 + S ) / ( 1.15D0 + 0.15D0 * S )
153 ASE = AE**DE
154 ZG3 = GAM( (S + 2.D0) * DE )
155 IF ( ZG3 .LE. 0.D0 ) GOTO 14
156 ZG1 = GAM(S * DE)
157 ZG2 = GAM( (S + 1.D0) * DE )
158 AUXIL = 4.D0 / (S * ASE)
159 XNE = CPCP * ( ZG2 + AUXIL * ZG3 ) / ( ASE * (ZG1 + AUXIL*ZG2) )
160C SUM OF N_E AT FIXED LEVEL
161 ZNE(IL) = ZNE(IL) + XNE
162 SL(IL) = SL(IL) + CPCP
163
164C CALCULATE THE ELECTRON LATERAL DISTRIBUTION FOR THE 2 SELECTED
165C OBSERVATION LEVELS
166 IF ( IL .EQ. IALT(1) ) THEN
167 IOL = 1
168 ELSEIF ( IL .EQ. IALT(2) ) THEN
169 IOL = 2
170 ELSE
171 GOTO 14
172 ENDIF
173
174C CALCULATION OF LATERAL ELECTRON DISTRIBUTION
175 IF ( SC1 .GE. 2.25D0 ) GOTO 14
176 G1 = GAM(4.5D0 - SC1)
177 G2 = GAM(SC1)
178 G3 = GAM(4.5D0 - 2.D0 * SC1)
179C DISTANCE IN CM BETWEEN PHOTON INITIATION AND OBSERVATION (VERTICAL)
180 DISTL = SECPAR(5) - TLEVCM(IL)
181C MODULATION BY AGE PARAMETER FOLLOWING LAGUTIN & UCHAIKIN
182C (AGE PARAMETER LIES BETWEEN 0.2 AND 2.25)
183 SM = 0.78D0 - 0.21D0 * SC1
184 SMRM = 1.D0 / ( SM * RMOL(IOL) )
185
186 CSGA = CPCP * SMRM**2 * G1 / ( PI2 * G2 * G3 )
187 SS2 = SC1 - 2.D0
188 SS45 = SC1 - 4.5D0
189 AS = SIN( SECPAR(4) )
190 BS = COS( SECPAR(4) )
191 TEX = DISTL * SQRT( 1.D0 - SECPAR(3)**2 ) / SECPAR(3)
192C DISTANCE TO THE CENTER OF THE CASCADE (IN CM)
193 XS = SECPAR(7) + TEX * BS - XOFF(NOBSLV+1-IOL)
194 YS = SECPAR(8) + TEX * AS - YOFF(NOBSLV+1-IOL)
195
196C NKG-FORMULA
197C LOOP OVER ALL LATERAL DISTANCES GETTING THE DENSITY IN MOLIERE UNITS
198 DO 171 M = -10,10
199 IF ( M .EQ. 0 ) GOTO 171
200C X DIRECTION
201 YM = SMRM * MAX( SQRT((DISX(M)-XS)**2 + YS**2), 1.D0 )
202 CZX (M,IOL) = CZX (M,IOL) + CSGA * YM**SS2 * (YM+1.D0)**SS45
203C Y DIRECTION
204 YM = SMRM * MAX( SQRT(XS**2 + (DISY(M)-YS)**2), 1.D0 )
205 CZY (M,IOL) = CZY (M,IOL) + CSGA * YM**SS2 * (YM+1.D0)**SS45
206C XY DIRECTION
207 YM = SMRM *
208 * MAX( SQRT((DISXY(M,1)-XS)**2 + (DISXY(M,2)-YS)**2), 1.D0 )
209 CZXY(M,IOL) = CZXY(M,IOL) + CSGA * YM**SS2 * (YM+1.D0)**SS45
210C YX DIRECTION
211 YM = SMRM *
212 * MAX( SQRT((DISYX(M,1)-XS)**2 + (DISYX(M,2)-YS)**2), 1.D0 )
213 CZYX(M,IOL) = CZYX(M,IOL) + CSGA * YM**SS2 * (YM+1.D0)**SS45
214 171 CONTINUE
215
216 14 CONTINUE
217
218 RETURN
219 END
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