1. 1 Adjustments to D  ’s Run IIa measured luminosity G. Snow / University of Nebraska for the D  Luminosity Group 29 November 2006 OK, you asked for it ….

2. 2 Already presented to this group The new “Luminosity Constant” to be used for data collected since October 20, 2005 – the date of the switch from the NIM to VME readout electronics for the Luminosity Monitor Detectors Old constant = 54.0 mb  3.5 mb (6.5%) New constant = 48.0 mb  2.6 mb (5.4%) The new constant was put online on September 29, 2006, 23:00 central time during Store 4989 Since the change implies an increase in the reported integrated luminosity of 12.5% for the period between October 20, 2005, and September 29, 2006. Luminosity constant, the effective Luminosity Monitor (LM) cross section for detecting inelastic events

3. 3 Recall that an important ingredient in the new constant determination was the VME-enabled ability to match data and Monte Carlo multiplicity distributions Luminosity Measurement Counter Multiplicity Red hist = MC Blue points = data What about the rest of Run IIa?

4. 4 NIM era VME era I=4750 I=4550 Fall 04 shutdown Baseline shift removed Correction for deadtime End Run IIa A B C D E

5. 5 PeriodDatesRun Range A Beginning RunII (4/20/2002) to Fall 04 shutdown (8/23/2004) 151817 to 196584 B 12/7/2004 to 12/19/2004 201537 to 202111 C 12/19/2004 to 3/17/2005 202152 to 204805 D 3/17/2005 to 10/20/2005 204806 to 211213 E 10/20/2005 to Spring 2006 shutdown (2/22/2006) 211214 to 215670

6. 6 Measurements Before and After Transitions Moving backward in time Constant for period E (VME constant) requires an adjustment of 54/48 = 1.125 (5.4% uncertainty) Influences periods A-E Comparisons of NIM and VME luminosity were made at different instantaneous L in different stores during period D L-dependent, influences periods A-D Comparisons before and after deadtime correction L-dependent, influences periods A-C Comparisons before and after baseline correction L-dependent, influences periods A-B Measurement of effect of magnet current on L Influences period A L 4550 /L 4750 = 1.026  0.006 (0.58% uncertainty) (See later)

7. 7 A word about the “12.5%” Non-diffractive Diffractive Two main physics processes in inelastic events

8. 8 A word about the “12.5%” Overlapping diffractive first diffractive collision in crossing second diffractive collision in crossing With many interactions per crossing at high luminosity, overlapping diffractive events feed into the non-diffractive sample Acceptance increases at higher luminosity, –Over-estimate luminosity if you don’t take this into account

9. 9 Luminosity-dependent correction to the 12.5% This has always been a part of the luminosity calculation via Improved electronics and MC give us a better measurement of the rate: –Old: 6.3 mb singles cross section –New: 9.4 mb singles cross section Change in period E luminosity Fit  12.5%  [1.0 - (1.71  10 -4 )L + (2.49  10 -7 )L 2 ]

10. 10 NIM to VME switch Measured before switch with both systems operating y(L) = 1.02 –(9.35  10 -4 )L + (7.41  10 -6 )L 2 Affects Periods A-D Deadtime correction Measured with and without y(L) = 0.998  exp[(1.5  10 -5 )L 2 ] Affects Periods A-C Band represents  1  (  3  ) error on fit function using errors on fit parameters and their correlations. L VME /L NIM L with /L without (Note vertical scales)

11. 11 Baseline correction Measured with and without y(L) = 1.0 +(7.04  10 -4 )L +(8.37  10 -6 )L 2 –(1.88  10 -7 )L 3 Affects Periods A-B L with /L without Luminosity vs. Magnet Current Measurement of L vs. current after Fall 2004 shutdown Affects Period A Leads to correction L 4550 /L 4750 = 1.026  0.006 (B field affects PMT performance)

12. 12 Radiation damage Measurements of mild radiation damage to Run IIa LM scintillators led to the replacement of the scintillator wedges for Run IIb. Measurements performed: Visual inspection. Transparency measurements with spectrophotometer. Radioactive source measurements. Cosmic ray test stand. Measurements give consistent indications that the LM wedges suffered 10-15% degradation in light output and/or transmission in the few centimeters closest to the beam during their exposure to >1 fb -1 particle flux. Can we see the effect of he radiation damage in something we can measure or simulate? Yes and yes. We correct for the effect of the radiation damage over the course of Run IIa.

13. 13 Radiation damage New scintillator Exposed scintillator PMT Beam end Note decrease in response near beam Cosmic ray test stand Light output profiles derived from such measurements are modeled in the Monte Carlo that simulates scintillator response.

14. 14 Ratios of LM efficiency with and without radiation damage VME electronics: No effect NIM electronics: 0.975±0.005 That is, MC predicts LM efficiency reduced by 2.5% with radiation damage We apply an exposure-dependent correction in the 4 NIM periods NIM corrections become smaller as you move back in time We use a “stair-step” constant correction for each of the 4 NIM periods Radiation damage Distance from beam (cm) MC weighting factor for light output Closed: new Open: damaged PMT position

15. 15 Radiation damage correction PeriodMultiplicative Correction% Correction A0.9839-1.6% B0.9890-1.1% C0.9904-1.0% D0.9959-0.4% E1.000.0%

16. 16 Muon yield (pseudo cross section) defined as Reconstructed muons Integrated L (  b) Do we see the radiation damage in other measured rates? First observe that the luminosity corrections remove a lot of the structure observed in the muon yields using uncorrected L

17. 17 However, the effect is about 5% end to end Now understood in terms of annealing between dismounting scintillators and the measurements of the radiation damage Hence, assign a generous uncertainty on the radiation damage correction Under the assumption that the numerator is stable, the decreasing denominator could be interpreted as quantifying the radiation damage

18. 18 Curves indicate max L inst for each period Back-propagation correction functions Period E Period D Period C Period B Period A

19. 19 PeriodCorrection Function A f A (L) = f B (L)  1.026  (0.9839/0.9890) B f B (L) = f C (L) [1.0 + (7.04  10 -4 )L + (8.37  10 -6 )L 2 - (1.88×10 -7 )L 3 ]  (0.9890/0.9904) C f C (L) = f D (L) [0.998  exp[(1.50  10 -5 ) L 2 ] ]  (0.9904/0.9959) D f D (L) = f E (L) [ 1.017 – (9.35  10 -4 ) L + (7.41  10 -6 ) L 2 ]  0.9959 E f E (L) = 1.125  [1.0 - (1.71  10 -4 )L + (2.49  10 -7 )L 2 ] Table of correction functions (L in units of E30) “L” is the uncorrected luminosity throughout the formulas above

20. 20 Period A Black uncorrected = 450.9 pb -1 Red corrected = 525.3 pb -1 Profile Running sum or integral – plateau is integrated L L most

21. 21 PeriodUncorrected L int Corrected L int % Increase A 450.9 pb -1 525.3 pb -1 16.5%17E30 15.4% B 6.8 pb -1 7.8 pb -1 14.6%21E30 13.3% C 125.0 pb -1 142.3 pb -1 13.8%25E30 11.6% D 394.3 pb -1 435.9 pb -1 10.6%25E30 11.4% E 182.8 pb -1 203.8 pb -1 11.5%27E30 12.0% Total1159.8 pb -1 1315.1 pb -1 13.4%13.1% % increase using only correction at L most Summary of effects on integrated (recorded) luminosity

22. 22 Uncertainties associated with the Run IIa luminosity Consider period A since it is subject to the 5 multiplicative corrections and contains half the Run IIa luminosity. New VME constant carries a  5.4% uncertainty. The NIM to VME correction uncertainty causes  0.27% shifts. The deadtime correction uncertainty causes  1.00% shifts. The baseline correction uncertainty causes  0.40% shifts. Magnet shift constant carries a  0.58% uncertainty. The radiation damage correction carries a ±2.5% uncertainty Adding in quadrature yields an overall uncertainty of 6.1% Quote  6.1% as the Run IIa luminosity uncertainty. (Dominates)

23. 23 A lot of work in the electroweak group to cross check the adjusted integrated luminosity using the measured cross sections for inclusive Z  e + e - and Z   +  -. Numbers are not yet released outside the collaboration, but the Z cross sections, calculated using the adjusted luminosity, agree well with theory predictions. FERMILAB-TM-2365-E (2006), to be released soon, will summarize D  ’s adjusted Run IIa luminosity. FYI: Marj Corcoran / Rice University will join me as co-convener of D  ’s luminosity working group in January 2007.

24. 24 Backup Slides

25. 25 Comparison of new Period E constant to previous constant Counter efficiencies overestimated previously 91%  85% LM detector acceptance overestimated previously 83%  79% 3 other small effects at the 1-2% level All in same direction, accounting for shift of constant outside previous uncertainty New constant uncertainty of  5.4% has about equal contributions from: Left piece  3.7% Right piece  4.0% D  Note 4958 CDF, E710, E811 Old New