Changes between Version 1 and Version 2 of perWeight

Timestamp:

Mar 5, 2016, 11:37:46 PM (9 years ago)

Author:

gallmei

Comment:

copying text from Olli thesis

perWeight

@@ -1 +1 @@
 = 'perturbative' and 'real' particles; the perturbative weigth =
+
+== 'perturbative' and 'real' particles ==
+
+(following text is taken from: O.Buss, PhD thesis, [http://www.uni-giessen.de/cms/fbz/fb07/fachgebiete/physik/einrichtungen/theorie/theorie1/publications/dissertation/buss_diss pdf], Appendix B.1) 
+
+For some calculations, e.g. low-energetic πA or γA collision, it is a good assumption, that the
+target nucleus stays very close to its ground state. Henceforth, one keeps as an approximation
+the target nucleus constant in time. This basically means that the phase space density of
+the target is not allowed to change during the run. The test-particles which represent this
+constant target nucleus are called ''real'' test-particles. However, one also wants to consider the
+final state particles. Thus one defines another type of test-particles which are called ''perturbative''.
+The ''perturbative'' test-particles are propagated and may collide with ''real'' ones, the products are
+''perturbative'' particles again. However, ''perturbative'' particles may not scatter among each other.
+Furthermore, they are neglected in the calculation of the actual densities. One can simulate in
+this fashion the effects of the almost constant target on the outgoing nucleons without modifying
+the target. E.g. in πA collisions we initialize all initial state pions as ''perturbative'' test-particles.
+Thus the target stays automatically constant and all products of the collisions of pions and
+target nucleons are assigned to the ''perturbative'' regime.
+
+Furthermore, since the ''perturbative'' particles do not react among each other or modify the ''real''
+particles in a reaction, one can also split a ''perturbative'' particle in \(n\) pieces (several ''perturbative''
+particles) during a run. Each piece is given a corresponding weight \(1/n\) and one simulates like
+this \(n\) possible final state scenarios of the same ''perturbative'' particle during one run.
+
+
+
+== the perturbative weigth ==
+
+the variable `perWeight` in the [//Documentation2016/code/typeDefinitions/particleDefinition_f90.html#robo688 definition of the particle type]