request to identify the error

Dear Fluka Experts,
     I am trying to simulate the experiment given in the paper entitled
"The Angular Distribution of the Photo neutrons from Beryllium." B.
Hamermesh et. al, Phy. Rev., Vol 76(5), pp 611, (1949).
     In his experiment the incident gamma energy was used 2.76 MeV on the
beryllium target and measured the photneutrons at various angles. For
the detection of neutrons he has used the Bf3 pulse ion chamber
embedded in paraffin cylinder. The distance between the source-target
and target-detector was kept by him 10 cm and 66 cm respectively.
       The results obtained in this paper shows peak at 90 degree. I have
tried to simulate the same experiment by keeping the same parameters in
FLUKA. I have checked the neutron flux at 0, 45, 90 degree. In addition I
have also checked the double differential neutron yield w.r.t. kinetic
energy and angles. But the simulated results are not similar to the
experimental one. In simulated case it shows nearly isotropic distribution
of neutrons. I am attaching herewith my input file for your ready
reference.
       The link to the reference paper is as follows
http://prola.aps.org/abstract/PR/v76/i5/p611_1

     Thanking you.

Patil B. J.

Mr. Bhushankumar Jagnnath Patil.
Microtron Accelerator Lab.
Department of Physics,
University of Pune,
Ganeshkhind, Pune 411007
Ph. No. Off. 020-25692678 Ext. 421
Mob. 9823968377
Webpage http://physics.unipune.ernet.in/~bjp
Alternate e-mail amolbhushan_at_gmail.com