Normalization of yield data

==Introduction==

Any arbitrary overall normalization of the gamma-ray yield data is acceptable, unless the user is trying to normalize to the collision partner's gamma-ray yields or to the elastic cross section.  This is because Gosia fits one overall normalization constant to all yield data, representing the factors of beam current, beam time, etc.

==Ge detector solid-angle corrections==

If all of the Ge detectors span the same solid angle, then all of the data will be consistent if each count is efficiency-corrected by dividing by the relative efficiency <math>\epsilon (E_\gamma)</math> with an arbitrary overall normalization.  However, if two data sets from different detector ''[[physical_germanium_type | types]]'' are included, then the following additional correction is necessary, since Gosia calculates (OP,INTI) yield per unit Ge solid angle to be used in fits (OP,MINI).

Gosia expects to read "corrected" yields of 

<math>Y = N_{raw} / [\epsilon(E_\gamma) \Delta\Omega_{Ge}]</math>,

where <math>Y</math> is the "corrected yield," <math>N_{raw}</math> is the measured count, <math>\epsilon(E_\gamma)</math> is the relative (or absolute) Ge detector efficiency and <math>\Delta\Omega_{Ge}</math> is the solid angle subtended by the germanium detector.  Here, the solid angle is in units of sr (steradians).  Obviously, if all Ge detectors span the same solid angle, then the <math>\Delta\Omega_{Ge}</math> term can be absorbed into the arbitrary overall normalization.

However, if two or more of the Ge detectors subtend different solid angles, the <math>\Delta\Omega_{Ge}</math> term should be included.

In cases where the overall normalization doesn't matter, the efficiency can absorb the solid angle and be taken on a scale of 0 < efficiency < 4pi, ''but the solid angle factor must not be included twice.''

===Exceptions===

If the counts from different types of Ge detectors are being summed into one data set, and there are no other data sets (Ge detectors or arrays), then the <math>\Delta\Omega_{Ge}</math> term amounts to only an overall normalization and can be neglected.

The OP,RAW command can be used to pass data to Gosia without an efficiency correction.  The solid angle divisors are still required.