all SUSY 05 production until Oct 28 2005 has suffered a very slight mismatch in the magnetic field between the 8_7_1 Digi and the 8_7_1 DST that amounts to a 1.5% bias e.g. in the muon PT

0. the first sample that was used to validate the fix of the field n the .orcarc writeDST card is Peter Kreuzer's technicolor sample. The fix is the addition of the card as follows

DST_ORCA_8_7_1_VolumeBasedMagneticField_Id_1478.txt DST_Stream_ORCA_8_7_1_VolumeBasedMagneticField_Id_1479.txt

and the result of the setting is attached.

1. would you please run partly on your sample's Digis and check track resolution (muon etc as per requirement in your analysis) and estimate how your result is changing due to the shift (compare with the result by running on the DST which has the +1.5% bias- see attached plots from Peter)

2. if you are comparing with FAMOS you must have seen already the same bias (sine the VolumeBasedMagneticField has been put in since sometime by Patrick). please check

3. This effect is not yet checked in versions of OSCAR >3_9_x and ORCA> 8_13_x

4. all currently running su_05 samples will be DSTed with the above ** VolumeBasedMagneticField_Id_1478.txt card and be published as in Peter's technicolor sample with indication vbmf

su_DST8713_vbmf_2x1033PU_g133_OSC

1. 1. If you have been running private signal productions, check your cards and result also. The card in question needs to be in the Digitization step also.

6. For Nov 18, the next SUSYBSM, pelase prepare a slide to show pt resoltuions and how your analysis is affetced.

Luc, Maria.

thanks to Wolfgang, Teddy, Tim, Stephan, the CERN and GridKa production teams and Peter for helping debunk this issue (and for sure a number of others who we forget)

- MariaSpiropulu - 30 Oct 2005

• ana_tc.pdf: 1.5% bias