Date: Mon, 01 Oct 2001 19:14:59 -0500 From: Caroline Milstene Subject: resuming stuff Sender: owner-ckm@listserv.fnal.gov To: Peter_Cooper MIME-version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII The correlations were missing CKM Geant generated beam, generated for the decay channels of our choice, flag IKINE=2 After discussions with Rick I have added them. Below is the summary of the changes. Attached are the new distributions (kpar.ps) and the old one without correlation and with an "ideal" Gaussian distribution for the momentum. The figures are refered in the text below Caroline -------------------------------------------------- MEMO: CKM Geant generated Beam C. Milstene Whenever the flag IKINE=2 is used in ckminit.kumac of CKM Geant, the beam kaon is generated at the Entry of the UMS following a set of distributions to decay to the channel of our choice .e.g. k->pi+p0 Until now, the position of the vertex, the angles and the absolute momentum of the kaon beam were generated separatly, assuming no correlations, They were following the distributions I extracted from Rick's Beam-Geant. But, there are actually correlations between y and theta_y as can be seen in the figure 70015 (1st set of plots attached), therefore I did modified the generation to take them into account. The momentum generation has been modified too. Until now the momentum was generated using the "mathematical expression" of a Gaussian with the right sigma, as added by Erik. Now histogram 70012 is the actual distribution for the momentum obtained from Beam-Geant too. I also extended the code to deal with the incoming pi^+ componant of the beam. In that way it will be possible to generate a 22 GeV pi^+ beam with a choosen decay (e.g. mu nu) in much the same way it was done until now for the kaon. e.g. in ckminit instead of using VEC/CREATE ubuf R 0. VEC/CREATE br(2) R 100. and then VEC/CREATE md(2) I 807 SPART 99 'K+pi2' 4 0.4937E+00 1. 0.1237E-7 ubuf ubuf br md and then set Kine 99 one can now write, for example for the decay pi--> mu nu VEC/CREATE ubuf R 0. VEC/CREATE br(2) R 100. and then VEC/CREATE md(2) I 504 SPART 99 'pi+mu2' 4 0.13957E+00 1. 0.2603E-7 ubuf ubuf br md and then set Kine 99 The particle is defined by its MASS which is the element in the 5th column and it is important to put the right number there Remark: in the 7th column is the life time In the case of the pion too, there is a correlation between theta_y and yvertex, as seen in figure 70025 and those variables are not generated separatly. The proton ... does not... decay, but Rick mentionned to me that it might be "handy", when treating accidentals, to use the same method to generate the protons (with an infinite... very big liftime) following the distributions obtained from Beam-Geant. Again same method in ckminit.kumac, just replace the Mass and Lifetime. SPART 99 'Proton' 4 0.9382E+00 1. 1.E20 ubuf ubuf br md and then set Kine 99 Remark: You can put whatever you want for the decay mode as long as the life time is long enough... but YOU HAVE to put something ! I left the md(2) setup for pimunu ... Here too one can see in figure 70035 the correlations between theta_y and y_vertex. I have attached the postscript file which corresponds to the new kpar.hbook as well as the postscipt file which represents the "old" one. The cuts used to produce the distributions out of Rick's Geant-Beam files for the kaon, pion and protons are : -14.< x_vertex<14. -6. < y_vertex<6. -0.003