Luminosity and V0 trigger cross section estimations from vdM scan results (Update 3)

1. Luminosity and V0 trigger cross section estimations from vdM scan results(Update 3) K. Oyama, G. De Cataldo, A. Di Mauro, C.Garabatos, and F. Antinori ALICE Trigger Meeting 9, July, 2010

2. Overview So far done • Pile-up correction … done (not changed since last update) • Using new BCT data for bunch intensity … done (not changed) • Secondary Gaussian inclusion to obtain the luminosity … done(but result is changed slightly due to the last point of this page) New this time • Last attempt: direct integration of the shape • Average top rate with zero separation ALICE Trigger Meeting

3. Numerical Sum normalized shape bunch intensity • Assumption (factorized in x and y) • For x-scan with separation b • The sharpness factor P & QFor Gaussian approx, P=1/(2x) • Sum of rate over b • The top (no displacement) rate • Divide B by A, then obtain the sharpness, luminosity and cross section • To apply for discrete values (in our vdM scan, separation step is constant = 22.42 [m]) A B ALICE Trigger Meeting

4. Numerical Sum (Result) • Integral • Sx = 152.17  0.67(stat.) [Hz mm] • Sy = 162.20  0.69(stat.) [Hz mm] • Separation-zero values (top rate) with pile-up corrections (took max. values) • Rx(0,0) = 986.72  10.93(stat.) [Hz] • Ry(0,0) = 975.08  10.87(stat.) [Hz] note: Rx and Ry are different • Sharpness • P = 6.484  0.077(stat.) [/mm] corresponds to Gauss x = 43.50 [m] • Q = 6.011  0.072(stat.) [/mm] y = 46.92 [m] • Luminosity and cross section • L = kb f N1 N2 P Q = ( 1.576  0.027stat ) x 1032 [s-1m-2] • v0 = 62.24  0.12(stat) [mb] (statistical error 0.2 %) where the average top rate ½ [Rx(0,0) + Ry(0,0)] = 980.90 [Hz] is used • Systematic errors come into this method: • N1, N2: same as before … 5% • Top rate fluctuation … 0.6% • Overall is dominated by N1, N2 7% ALICE Trigger Meeting

5. History + Correction to Past Result May14: 72 mbvery rough estimates (beam intensity/2) … discarded Jun. 04: 60.7 mbbunch intensity but also discarded because we got corrected data later Jun. 29: 63.0 mb corrected for bunch intensity data provided from LHC and pile-up still using primary Gaussian only for both sigma and top-rate Jun.29: 64.6 mb (the value used now for publishing) pile-up correction and add two Gauss for top-rate (992 Hz) (x-scan value) if we use not 992 Hz but average between x and y (980.5 Hz)  63.9 [mb] Jul. 01: 68.6 mb full consideration of primary + secondary gaussians (integration) and also pile-up corrected top-rate (992 Hz) if we use not 992 Hz but average between x and y (980.5 Hz)  67.8 [mb] Jul. 09: 62.24 mbNumerical sum method, using already average top-rate (980.90 Hz) * Standard deviation of all values appeared since Jun. 29  5.6 [mb] ~ 9% * If we select only the “average” top rate value  4.62 [mb] ~ 7.5% ALICE Trigger Meeting

6. To Do • More check and cross check on calculations, especially for the last two (two-gauss and numerical sum) • Internal-note is being written • Muon trigger data available for the last vDM scan [Daniel] … to be checked • Scanning existing run data for V0-AND and make summary (not yet started) ALICE Trigger Meeting