Lifetimes at DESY. Mark Lomperski DESY-MIN. 2.December.04. Status (Part 1). One Algorithm used at DORIS, PETRA-e and PETRA-p, HERA-e and HERA-p: e+/e- tau ~20 hrs, p+ tau > 1000 hrs Keeps most of the people happy most of the time…. but not all the time…
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Accurately follow the time dependence of lifetime disturbances! With a small STATISTICAL error, please.
The “problem” (lifetime breakdown) may be solved, but the tau algorithm can take too much time (>20 s) to reveal this.
HERA-e ramp from 12 to 27.5 GeV
Start with 27 mA & 18 hr. Lose ~50 uA in 20 sec – twice. Tau drops to 4 hrs. End at 26.5 mA
Store “raw” data for offline analysis
Add well-defined lifetime “events” to the data (lifetime breakdowns, beam loss, noise-spikes,…)
30 minutes of DORIS Data. Lifetime ~12 hours
Standard Algorithm: breakdown not detected (so history-depth not shortened)
Chi^2 Algorithm: No effect until ~3 sec after event. Then quick reaction.
(He uses one for his Orbit-Stabilization Algorithm).
A lifetime measurement with real-time response is needed.
Low frequency DCCT noise (drifts?) makes a simple/direct solution, well, difficult.
It is necessary to average over many seconds.
Our Standard Algorithm, which compares individual currents, is blind to small effects.
We’ve started work on Other Algorithms.