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HBD Alignment in Run-10. Mihael Makek Weizmann Institute of Science. HBD Meeting, 5/1/2011. The dataset. Goal: determine time variations of HBD offsets Selected data: CCNT - hadrons Good quality tracks (31,51,63) n0 < 0 Emcal matching Selected subsample: p > 0.7 GeV/c Hbdsize = 1
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HBD Alignment in Run-10 Mihael Makek Weizmann Institute of Science HBD Meeting, 5/1/2011
The dataset • Goal: determine time variations of HBD offsets • Selected data: CCNT - hadrons • Good quality tracks (31,51,63) • n0 < 0 • Emcal matching • Selected subsample: • p > 0.7 GeV/c • Hbdsize = 1 • Restricted geometry in HBD modules • Centrality > 50% M. Makek - WIS
Sign dependence Select particles with p > 0.7 GeV/c to avoid sign dependence M. Makek - WIS
HBD Offsets vs Run Number The blue line – weighted average EAST The red line – weighted average WEST M. Makek - WIS
HBD Offsets by module • Offset variations for N/S modules in the same sector: • visible for almost all sectors • visible in z and phi • different in E and W M. Makek - WIS
N/S variations scenario Correlation between dz and dphi offsets for different runs What can cause difference in N/S offsets within the same sector and move dz and dphi simultaneously? Geometry, e.g. rotation of the HBD around x axis (horizontal) M. Makek - WIS
N/S variations scenario a -Dy Dy -Dz Dz • Two modules in the same sector shifted in different directions! • z and phi shifts correlated! y • Estimate the angle of rotation from the data: • Df~ 1 mrad • Dy ~ RDf~ 580 mmx 0.001 = 0.58 mm • Dy ~ r0a ~ 125 mma a ~ 5 mrad z x M. Makek - WIS
N/S variations scenario M. Makek - WIS
Alignment correction • The offsets are varying for modules inside the same sector (rotation, tilt) • The offsets are varying with time (carriage movements, beam, DC performance, etc.) • Try to decouple these factors: • Correct for detector rotation by extracting the slope and the intercept of hbddx and hbddy vs phbdz for each sector (should be constant during Run10) • Correct for residual module offsets for different run groups within which the offsets are stable M. Makek - WIS
Correct for detector rotation M. Makek - WIS
Correct for time dependance (1) (2) (3) (4) (5) (6) (7) The blue line – weighted average EAST The red line – weighted average WEST M. Makek - WIS
Run groups 1 – 6: 200 GeV 7: 62 GeV M. Makek - WIS
Offsets in phi corrected M. Makek - WIS
Offsets in z corrected M. Makek - WIS