The How To Use Lagets 3He(e,e'p)d Code Manual

by Michael Kuss
26 June 2000

updated by Douglas Higinbotham
23 June 2001



You will find all the programs mentioned in the manual on BLUE in the directory ~e89044/theory/laget. The executable can not be copied. So use, ln -s ~e89044/theory/aget/he3pd.out, to link the code to your directory.
Also, the notation he uses can be found in New Vista in Electro-Nuclear Physics, Eds. E.L. Tomusiak, H.S. Caplan and E.T. Dressler, (Plenum, New York, 1986), p. 361. It's the proceedings of a conference held in Banff. I haven't checked if it is in the JLab library. You may want to check other Laget papers, or Kuss's thesis on the web.

The code is simple to use. You just type he3pd_full, and the code runs. It reads it's input from he3pd.dat and writes to output.r. A particularity of Laget's code is that a result.r has to exist, though it can contain everything, even be an empty file. This "whatever" file will be overwritten by the "real" output. The program will terminate with the following output, don't worry about it: 

dofio: [-1] end of file
logical unit 5, named 'he3pd.dat'
lately: reading sequential formatted external IO
part of last data:   10.16  4^J^?|
Abort
Obviously, this is a totally normal termination.

he3pd.dat

This is the input file, it is long. I don't exactly remember what the all the lines are, I assume they have something to do with the wave function, momentum distribution etc. used. The last line is the interesting one to be modified: 
 837.0 4803.0   16.40 180.00  10.16  4 0 0
The unit for energies, masses and momenta is MeV, and degrees for angles. The first 4 numbers denote energy transfer omega, beam energy E, electron angle theta_e, and the angle of the hadronic plane phi_h. phi_h is defined as in the New Vistas or Fig. 2.2 on p. 9 of Micheal's thesis, i.e. forward of the momentum transfer k phi_h is 0° (Sigma2), and backward it is 180° (Sigma1 and Sigma3).
The fifth number is an increment for the proton angle theta_h_cm in the cm system measured relative to k, and the last is the number of angles to be computed, minus 1. E.g., for the example shown three (4-1=3) angles in the cm system would be computed, 0°, 10.16°, and 20.32°. Here, the increment was chosen that 10.16° is the cm angle for kin #4.
The sixth and seventh numbers are new. They are used as switches. 
0 0 PWIA and FSI
0 1 PWIA and FSI and 2-Body
1 0 PWIA and FSI and 3-Bdoy
0 0 PWIA and FSI and 2-Body and 3-Body

Please note that Laget reads he3pd.dat with formatted input, thus the position of the numbers is important. I haven't tried, it seems to me that each field has to be 7 characters wide. I know the following two lines work, the first is from Laget's original example input file. 
<-----><-----><-----><-----><-----><----->
 836.504795.00  16.43 180.00  15.00  3    0 0
 837.0 4803.0   16.40 180.00  10.16  4    0 0

result.r

result.r prints 132 characters wide, so you better use a wide screen to look at it. 
1 HE3(E,E")PD   FADDEEV PARIS/HANNOVRE 18 CANAUX
  SANS 3 CORPS
 EG=  837.00     PCM=  847.33     W=  3322.3     TL=  831.81    EK=  1500.2    SQ= -1.5500     ENP=  508.50     EGCM=  240.96    

 EINC=  4803.0     TETA=  16.400     PHI=  180.00    
 EPSI= 0.94313     REPSI=  1.4239     FLUX= 0.51963E-05MEV-1
  A PARTIR DE J0
0OMEGA= 0.10000     PP1=  1500.6     TETAP= 0.55953E-01 PP2=  1.5811     TETAN= -103.76      JAC=  3.1362    
 ZERO    TRANS.=  823.94     LONG.=  188.39    INT.= 0.74105E-03 TRANS.LONG.= -1.2126     TOTAL= 0.16295E-01
 REABS.  TRANS.= 0.43826E-01 LONG.= 0.62155E-02INT.=-0.29552E-03 TRANS.LONG.=-0.12340E-03 TOTAL= 0.80236E-06
 TOTAL   TRANS.=  816.86     LONG.=  186.84    INT.= 0.69412E-01 TRANS.LONG.= -1.2798     TOTAL= 0.16155E-01
 ELECTRONS NON POLARISES POLAR. PROTON
        STN= 0.13827E-01 SLN=-0.13586E-02 STTN=-0.59837E-01 STLN=-0.20635     PNORM0=-0.34066E-03
 ELECTRONS POLARISES  POLAR.  PROTON   SIGTTS=-0.10495E-01 SIGTLS=  525.25     POLAR.TRANS.= 0.12906    
                                      SIGTTL=  816.82     SIGTLL= -1.2727     POLAR.LONG. = 0.27360    
                                                          SIGTLN=  525.29     POLAR.NORM. = 0.93452E-06
 ELECTRONS POLARISES TRANS.LONG.= 0.17254E-01 ASYMETRIE FAISCEAU= 0.30695E-10
0OMEGA=  10.160     PP1=  1493.5     TETAP=  5.7437     PP2=  150.14     TETAN= -84.572      JAC=  3.1106    
 ZERO    TRANS.=  17.763     LONG.=  4.3225    INT.= 0.16954     TRANS.LONG.= -2.6684     TOTAL= 0.29418E-03
 REABS.  TRANS.= 0.64447E-01 LONG.= 0.38541E-02INT.=-0.22984E-01 TRANS.LONG.= 0.17473E-02 TOTAL= 0.79028E-06
 TOTAL   TRANS.=  16.617     LONG.=  4.1370    INT.= 0.32393     TRANS.LONG.= -2.4961     TOTAL= 0.27914E-03
 ELECTRONS NON POLARISES POLAR. PROTON
        STN=-0.11222E-01 SLN=-0.12848E-01 STTN= 0.48659E-01 STLN=-0.57418E-02 PNORM0= 0.83253E-03
 ELECTRONS POLARISES  POLAR.  PROTON   SIGTTS=-0.13085E-01 SIGTLS=  10.738     POLAR.TRANS.= 0.15121    
                                      SIGTTL=  16.582     SIGTLL= -2.4411     POLAR.LONG. = 0.28477    
                                                          SIGTLN=  10.961     POLAR.NORM. = 0.11194E-05
 ELECTRONS POLARISES TRANS.LONG.= 0.53791E-02 ASYMETRIE FAISCEAU= 0.54932E-09
0OMEGA=  20.320     PP1=  1472.4     TETAP=  11.528     PP2=  299.81     TETAN= -78.946      JAC=  3.0348    
 ZERO    TRANS.= 0.19201     LONG.= 0.54435E-01INT.= 0.69009E-02 TRANS.LONG.=-0.56799E-01 TOTAL= 0.26649E-05
 REABS.  TRANS.= 0.35838E-01 LONG.= 0.13029E-02INT.=-0.18021E-01 TRANS.LONG.= 0.78146E-03 TOTAL= 0.33407E-06
 TOTAL   TRANS.= 0.17472     LONG.= 0.43907E-01INT.=-0.66482E-02 TRANS.LONG.=-0.52433E-01 TOTAL= 0.21321E-05
 ELECTRONS NON POLARISES POLAR. PROTON
        STN= 0.16063E-02 SLN=-0.50115E-03 STTN=-0.50734E-02 STLN= 0.26506E-02 PNORM0= 0.90879E-03
 ELECTRONS POLARISES  POLAR.  PROTON   SIGTTS=-0.51107E-02 SIGTLS= 0.90341E-01 POLAR.TRANS.= 0.15020    
                                      SIGTTL= 0.16296     SIGTLL=-0.48572E-01 POLAR.LONG. = 0.31317    
                                                          SIGTLN= 0.96295E-01 POLAR.NORM. = 0.12561E-05
 ELECTRONS POLARISES TRANS.LONG.= 0.19961E-03 ASYMETRIE FAISCEAU= 0.26038E-08
0TRANS. ZERO=  5.1677     REABSORPTION= 0.26618E-01 TOTAL=  4.9219     MICROBARNS  RT= 0.13165     10-3 MEV-1
 LONG.  ZERO=  1.2369     REABSORPTION= 0.12737E-02 TOTAL=  1.1934     MICROBARNS  RL= 0.23174E-01 10-3 MEV-1
 TOTAL  ZERO= 0.32915E-04 REABSORPTION= 0.14456E-06 TOTAL= 0.31424E-04

POLARISATIONS INTEGREES  STRS=      0.      STRN=-0.50418E-03PNORM0= 0.59355E-04
                       STRTLS=  3.1668    STRTLN=  3.2131    PSIDE= 0.12849    
                               STRTTL=  4.9105    PLONG= 0.26993    
 PMAX=  1280.1          0.     PMIN=  220.09          0.    
 PPLUS=  1500.6     PMOINS= -358.85
The head contains kinematic parameters. You will recognize the energy transfer as EG, the beam energy as EINC, the electron angle as TETA and the angle of the hadronic plane as PHI. It calculates also several other variables, I don't remember all of them, but PCM is the cm proton momentum, W is the invariant mass of the photon-nucleus system, and EK the three momentum transfer. Again, units are MeV and for the angles degrees.
After the head, which ends with "A PARTIR DE J0", comes a paragraph for each cm proton angle, which is denoted as OMEGA (don't get confused by this). A few kinematical parameters are calculated, PP1 is the proton lab momentum, TETAP the proton lab angle, and JAC the Jacobian. For the cross sections, there are three lines. ZERO contains the PW calculation, REABS the correction terms only, and TOTAL is the coherent sum of both (this is the full calculation). In each line, TRANS. is the transverse, LONG. the longitudinal, INT. the transverse-transverse interference, and TRANS.LONG. the transverse-longitudinal interference part of (d_sigmax/d_Omega)cm in µb/sr. The last number TOTAL is the total differential cross section (d_sigma/d_Omegap/d_Omegae/dE)lab in µb/sr2/MeV. You calculate it using EPSI (virtual photon polarization), REPSI (kinematical factor for TRANS.LONG.), and FLUX (virtual photon flux in 1/MeV/sr), with the formula

d_sigma = FLUX · JAC · ( RT + EPSI · RL + cos(2·PHI) · EPSI · RTT - cos(PHI) · REPSI · RTL ).

Please compare with the notation of eq(2.12) on p. 10 of my thesis. Eq.(2.2) gives epsilon and eq.(2.14) the flux. This is for the cm system, so JAC is missing there. I remember the notation in the New Vistas is slightly different (I think the flux is computed differently), so please refer to the thesis.
The other lines give polarization information, I don't know anything about it, please ask Doug.

The last section of result.r lists integrals of the cross section. I cannot say anything about them, because I never used them. Laget uses a Monte-Carlo technique to compute his cross sections, which may or may not converge. In my thesis, were I measured the 3He(e,e'pi)X reaction as function of the pion momentum, the Monte Carlo often didn't converge for low cross section points. Thus, it was neccessary to identify these momenta, interpolate and integrate by externally.