03 study of 2009 slopes (jan)


 Purpose of this study is to evaluate how successful was our firts attempt to compute new 2009 HV for BTOW.

Short answer: we undershoot by a factor of 2 in HV power- see fig 4 left.

Input runs: 10066160 (new HV) and 10066163 (old HV) 

Fig 1. Pedestal distribution and difference of peds between runs - perfect. Peds are stable, we can use the same slope fit range (ped+20,ped+60) blindly for old & new HV.


Fig 2. Chosen HV change and resulting ratio of slopes - we got the sign of HV change correctly!

Fig 3. Stability test. Plots as in fig 2, but for a subset of towers we change HV almost nothing (below 2V) but yield was large. One would hope slope stay put. They don't.  This means either slopes are not as reliable as we think or HV is not as stable as we think.  

Fig 4.  Computed 'kappa' :  sl2/sl1=g1/g2=V1/V2^kappa for towers with good stats and HV change of at least 10 Volts, i.e. the relative HV change is more than 1%.  Right plot shows kappa as function of eta - no trend but the distribution is getting wider - no clue why?

Fig 5.  Computed 'kappa' as on fig 4. Now negative, none physical values  of kappa are allowed.