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Some Simple Thoughts on Medium-Term Luminosity. D. Schulte March 30, 2011. Luminosity Degradation with Time. Assume ATL motion A=0.5μ 2 /(ms) in the plot Could be (V.S.) A=3 μ 2 /(ms) Hence 2% loss after 150-1000s Need to optimise knobs in <150s. Jochem Snuverink.
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Some Simple Thoughts on Medium-Term Luminosity D. Schulte March 30, 2011
Luminosity Degradation with Time Assume ATL motion A=0.5μ2/(ms) in the plot Could be (V.S.) A=3μ2/(ms) Hence 2% loss after 150-1000s Need to optimise knobs in <150s JochemSnuverink
Luminosity Measurement and Optimisation • Aim for 10% pulse-to-pulse luminosity stability • 1% precision reached after 100 pulses = 2s • Measurement precision is comparable if we using knob tuning signals • 7% for 3 bunches = 1.2% for 100 bunches (Barbara Dalena) • Can perform 75 measurements in 150s • 15 scans of 5 points, ~1.6% error at each point • Will compromise luminosity during scan (signal needs to be comparable to measurement error) • Have to balance loss during scan and long-term loss • Identify knob optimisedsequency • Caveats • At lower luminosity scans might take longer • Have no margin in above calculation • But 1% precision may be a tight requirement • Full study is on the way • Needs to be reviewed
