-- MarkusMerschmeyer - 04 Oct 2005

S279 Invariant Mass dependence on B-Field

The Problem

During the first scans of the Jcl203l generation of the S279 data it became obvious that the invariant masses of $ \Lambda $ and $ K^0_S $ were too low (CalibrationStatusS279). To investigate this, I did a scan of runs 6900 to 7099 increasing the field by 0.0%, 1.0%, 1.5% and 2.5%, respectively (0.600 T, 0.606 T, 0.609 T and 0.612 T). The results are given below:

Data Scans with different B-Fields

  • Increasing the field brings up the invariant masses. The respective mean values are indicated by the dashed lines. The nominal masses of $ \Lambda $ and $ K^0_S $ are 1.115683 GeV/c$^2$ and 0.497672 GeV/c$^2$, respectively. Click here for a larger image:

Mean Invariant Mass as Function of B-Field

  • While the mean $ K^0_S $ mass is still too low at a 2.0% larger B-field, the mean $ \Lambda $ mass is already good at a field increased by 1.0 to 1.5%. So, even if there are deviations of the B-field (between different beam times) causing lower or higher invariant masses, they can not be the only effect at work. Click here for a larger image:
Topic attachments
I Attachment Action Size Date Who Comment
zmf_mass_all.gifgif zmf_mass_all.gif manage 53.0 K 2005-10-04 - 11:50 MarkusMerschmeyer xxx
zmf_mdep_all.gifgif zmf_mdep_all.gif manage 24.5 K 2005-10-04 - 11:50 MarkusMerschmeyer yyy
Topic revision: r3 - 2005-11-23, MarkusMerschmeyer
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