1. 1 PID, emittance and cooling measurement Rikard Sandström University of Geneva 2007-04-17 MICE Analysis phone conference

2. 2 Outline Emittance measurement Cooling measurement

3. 3 Emittance measurement bias at downstream tracker ref plane

4. 4 These plots are measurable quantities!

5. 5 Emittance measurement bias at TOF2 entrance

6. 6

7. 7 Conclusions, part 1 The emittance measurement bias from PID is small at the tracker reference plane. –The cooling channel scrapes high amplitude background. –Much of the background present at the end of the experiment decays in the downstream solenoid. –The bias prior to PID is of the order 10 -3. At TOF2 entrance the emittance measurement bias from PID is large. –PID is necessary. After PID analysis, all remaining bias is acceptable. –PID is sufficient. –The lowest momentum case could still be a problem. We must use the real tracker reconstruction to figure out what happens to decay events inside the solenoid!

8. 8 Cooling measurement Since the beams shown in previous slides have empty absorbers and RF turned off, it is not meaningful to study cooling with those. Instead a matched beam (using Matcher) with Holgers 207 MeV/c, 42 cm beta, was used in full Stage 6 operation. –This cooled 2.9%, while I hoped for 10%. With cooling bias, I mean ((e dn -e up )- (ε dn - ε up ))/ (ε dn - ε up ) where e is measured emittance, and ε is true emittance.

9. 9 Tracker resolution Assumed Gaussian tracker resolutions (from M. Ellis ’04) –  px =  py = 2 MeV/c –  x =  y = 0.5 mm –(These values are used in PID algorithm.) On the left: bias on emittance measurement as function of momentum resolution. –Bias dominated by momentum resolution –For bias < 10 -3, resolution must be < 1 MeV/c.

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12. 12 Conclusions, part 2 For the cooling measurement, the bias before PID is ~ 4-5 %. –PID is necessary. After PID, the bias is << 1%. –PID is sufficient. …or is the MICE target 10 -3 here too? (see “Historical document”) The remaining bias after PID, when cooling measured with smeared tracker values, is ~ 1.5%. –This is not enough. However, since the offset is fairly constant, can we correct for this?

13. 13 Conclusion summary The PID analysis is both necessary and sufficient for –emittance measurement –cooling measurement. The tracker performance is not sufficient as it is. –There is need for some sophisticated corrections to get the biases within acceptable limits. –If we trust G4MICE results, it might be a rather simple task.