From: Peter H. L. Christiansen (pchristi@nbi.dk)
Date: Thu Feb 20 2003 - 12:11:33 EST
Hi I think I figured out the problem with the TOFW efficiency. It was ofcourse the method. I forgot to take into account the decay of pions. This depends ofcourse on p, but the stronger correlation which I guess is the p/pi ratio depends on ta-ta-ta p_T, so this at least to me explains while the agreement is in p and not in p_T and also why the "efficiency" is better in the runs where TPM2 is clser to the TOFW. It would ofcourse be good to have a better way to estimate the TOFW efficiency, but for now I guess I will stick with 0.93 +-1%. A higher efficiency might be optained if one could solve the panel problem. This would also be good for the spectra since this panel problem might cause bumbs in them. Cheers Peter On Thu, 6 Feb 2003, Peter H. L. Christiansen wrote: > Hi > > I just wanted to mention that I did a test with more settings and found > that there is pt-scaling except for the runs where the MRS was moved back. > > The results can be checked at : > http://www.nbi.dk/~pchristi/BRAHMS/TOF/ > > Cheers > Peter > > On Thu, 6 Feb 2003, Peter H. L. Christiansen wrote: > > > Hi > > > > There is somehow two ways to interpret the results. > > > > 1) The pointing is worse at large angles in TPM2 so therefore it is also > > worse at low momentum > > 2) The efficiency is worse at low momentum therefore the efficiency is > > also worse at large TPM2 angles > > > > The way I understand the results is that it is the last point that is true > > becuase the efficiency seems to be the same in all settings if you look as > > a function of momentum while the angle dependence differs quite a lot. > > This also explains why the efficiency is lower in low field settings even > > though there are actual more straight tracks than in high field settings. > > If there is a monetum dependence it might be the result of multiple > > scattering or the energy deposited in the slat and will likely be > > different for different particle species (masses). > > > > Cheers > > Peter > > > > P.s : I am gonna try to run some more settings and see if they agree with > > what I shown so far. > > > > On Thu, 6 Feb 2003, Djamel Ouerdane wrote: > > > > > HI, > > > > > > I think the large alpha_x ineffiency is more due to the fact that the > > > matching tof-track is worse since it involves slats from outer panels more > > > (I'm not talking about the panels Peter has removed on purpose). > > > The matching in the x direction of each panel is better for middle > > > panels. In the y direction, this behaviour is even worse. Since the y > > > matching relies on the slat speed of light calibration, it is much better > > > in the middle panels where most of the tracks point to. > > > > > > Djam > > > > > > Djamel Ouerdane ------------------------------------------o > > > | Niels Bohr Institute | Home: | > > > | Blegdamsvej 17, DK-2100 Ø | Jagtvej 141 2D, | > > > | Fax: +45 35 32 50 16 | DK-2200 Copenhagen N | > > > | Tel: +45 35 32 52 69 | +45 35 86 19 74 | > > > | http://www.nbi.dk/~ouerdane | > > > | ouerdane@nbi.dk | > > > o---------------------------------------------------------o > > > > > > > > > > > > -- :-) --------------------------- )-: Peter H L Christiansen @ NBI EMAIL : pchristi@nbi.dk OFFICE : Tb1@NBI (353 25269) HOME : Frimestervej 22, 1. tv PHONE : 35824930/40840492 :-D --------------------------- \-:
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