User name gueye
Log entry time 06:02:18 on August 1,1999
Entry number 15033
This entry is a followup to: 14967
keyword=beam stability on target - CHL crash impact on dataLook at the beam stability for runs 25910 to 25933 to follow up on entry 14967 (where the runs 25905 to 25909 were analyzed) . All relevant figures are in the white "OTR and harp scans" binder located in the Hall C counting house.
1/ Fig 1 (left): beam position and angle on target. Seems stable.
2/ Fig 2 (right): beam energy drift from arc setting (information from 5 BPMs + arc optic).
* 25910-25923: beam energy stable within 0.8x10^-3. Run 25912 is a cosmic run and run 25913 had a lot of trips. Looking at the time dependence of the energy fluctuation, no obvious reason for the trips from energy stability is apparent but one can see a steady drift of 0.2x10^-3 after the origin of the trips were fixed.
* 25924-25933: beam energy stable within 0.8x10^-3 also but located at a different nominal value.
* There is a "jump" between the runs 25923 and 25924. Amusing that a CHL crash happened between these two runs. The machine came back with a diferent nominale energy !!
* The datum for run 254932 appears at -0.9x10^-4. Looking at the time dependence of the energy, one can see two different groups within this run: one with a -.18x10^-3 average energy drift and one at -0.2x10^-4. This run corresponds to the BCM calibration run. It seems that each group belongs to one group of data taking (we did twice the ramping from 20 to 80 uA). I do not have any explanation for that and actually it may not be very relevant since it is only a 2x10^-4 effect.
3/ One should not trust the absolute values quoted since no calibration of the code which extract this information has been done yet (in particular the matrix of the arc setting as of 1999). However, the relative deviations are relevant.
FIGURE 1
FIGURE 2
