n Flux Uncertainties for the NuMI Beam

1. n Flux Uncertainties for the NuMI Beam Sacha Kopp University of Texas at Austin

2. How Good is our Beam MC? • Beam flux starting with Fluka2005 model of particle yield off target. • NuMI has run several beam energy configurations (more on this later) • Error bars are from the beam systematic errors (particle production off the target, horn and target alignment, focusing errors, etc). “High” Energy Beam Setting “Medium” Energy Beam Setting “Low” Energy Beam Setting MINOS Data Calculated n flux

3. A Two-Prong Approach to Beam Systematics External Data and Auxilliary Alignment Runs of the NuMI beam Flexible Beam Design for in situ systematics measurements The “Two Buddha’s” Near Sensoji Temple, Asakusa, Tokyo

4. Focusing Systematics (Auxilliary Measurements) 5-story pagoda of Sensoji Temple, Asakusa, Tokyo

5. Neutrino Beam Focusing Systematics • Focusing systematics affect falling edge of n peak • Far/near uncertainty < 2% Focusing Peak Focusing Peak

6. Example: Ihorn uncertainty • Ihorn initially calibrated to 0.5% (1 kA) • We can see variations at level of ~1% • Extensive instrumentation necessary to see this effect (primary beam, target station, muon monitors) Mixed Mode Running NuMI-Only Running Stripline Temperature (C)

7. Example: Horn+Target Alignment • Survey horn and target positions by scanning the proton beam across them. • Several runs with and without the target in place • We built in numerous alignment features on horns, target • Discovered real ~1mm misalignments relative to optical survey!! R. Zwaska et al.,“Beam-Based Alignment of the NuMI Target Station Components at FNAL,” Nucl.Instrum.Meth. A568, 548 (2006).

8. Particle Production Off the Target (in situ Measurements using Flexible Beam Configurations) Sensoji Temple, Asakusa, Tokyo

9. Why Hadron Production Is Important to NuMI • Two-detector experiment for nm disappearance measurement. • NearFar flux prediction less sensitive to than ab initio flux calculation, but still important at 10-20% level. • But what should we use as error in predicted beam spectrum? (model correlation?) • A perpexing situation for a poor experimentalist

10. Compare Hadron Production Models A perpexing situation for a poor experimentalist… Fluka2001 Fluka2005 MARS–v.14 MARS–v.15

11. Available input data is sparse for “high energy” protons Now there is extensive data available from NA49 (not true at time of NuMI/MINOS analysis), Now also data from FNAL/E907 (see talk by J. Paley) Data Upon Which Models are Based Atherton 400 GeV/c p-Be Barton 100 GeV/c p-C SPY 450 GeV/c p-Be LE10/185kA Beam

12. Thick-Target Effects • Hadron production data largely from ‘thin’ targets. • Particles are created from reinteractions in NuMI target. • Approx 30% of yield at NuMI p0=120 GeV/c J-PARC MiniBooNE CNGS Fluka 2005 NuMI

13. NuMI Variable energy beam p+ with pT=300 MeV/c and p=5 GeV/c p=10 GeV/c p=20 GeV/c “Low” Energy target proton Horn 1 Horn 2 “High” Energy CRUCIAL POINT • Produce same En using several beam focusing configurations • Deconvolve systematics • Neutrino beam focusing • p/K production off target • Neutrino cross sections target Horn 1 Horn 2 NuMI Beam MC HE LE

14. NuMI Beam Configurations • Can vary • Horn current (pT kick supplied to p’s) • Target Position (xF of focused particles) • Plots show (xF ,pT) of p+ contributing to neutrino flux. • Similar plots exist for kaons • Acquired data from 8 beam configurations (here are shown 4) LE010/0kA LE010/185kA LE100/200kA LE250/200kA

15. Parameterizing Hadron Production • Used empirical form similar to BMPT to parameterize Fluka2005: • Fit was to a MC of our thick-target yield estimated by Fluka2005. • Tune parameters of the fit to match ND data.

16. ND Spectra After Reweighting (I)

17. ND Spectra After Reweighting (II)

18. ND Spectra After Reweighting (III)

19. ND Spectra After Reweighting (IV)

20. ND Spectra After Reweighting (V)

21. ND Spectra After Reweighting (VI)

22. ND Spectra After Reweighting (VII)

23. ND Spectra After Reweighting (VIII)

24. (xF,pT) weights • Result of the fit is set of weights in (xF,pT) plane that should be applied to p/K yields • Data prefers more low pT pi’s Region of LE beam focusing Region of insignificant focusing p+weights

25. Constraint of fit on p+/p- ratio • Anti-nu’s tune the p- flux off the target • Out put of fit agrees well with recent NA49 data • Also see talk by J.Paley on FNAL/E907

26. Constraint of fit on K/p ratio • Recent data from FNAL E907 to which we can compare • See talk by J.Paley later this session.

27. Final Result • F/N ratio unchanged by this procedure in focusing peak (expected). • This tuning changes spectrum in the high energy tail by ~10%, but it is stable to 2% • Constraint from ND reduces errors by 3 (Fluka2005)

28. nm Constraints on ne Flux • Intrinsic ne in beam from same meson decays as nm • Measurement of nm provides constraint. • KL not constrained by, must assume quark counting • Uncertainty in ne flux is ~6% at the far detector mne

29. Conclusions • Our analysis emphasizes direct measurements to constrain uncertainties associated with the beam. • Auxilliary test runs for horn, target alignment • In situ test runs using flexible beam configurations • Flexible beam configurations of NuMI permitted tuning hadron production yields to match the ND data • Fitted particle production consistent with NA49/MIPP • Fitted target position consistent with subsequent optical survey • Other focusing effects consistent with anticipated uncertainties. • We obtain constraints on ne flux as well. • Flux uncertainty at far detector reduced from (2-10)%  (2-4)%

30. Beam Systematics Work quickly Employ powerful techniques ‘two massive pulsed objects for focused outcome’ High School Sumo Championships Sumo Hall, Ryōgoku, Tokyo, 5 Aug. 2007

31. Backup slides

32. Discovery: Target z Misalignment • Data taken since Oct ’06 with new target • Observed shift in spectrum • Many effects excluded • Fit to data predicts 1.00.4cm shift of target in beam direction • Such a shift has since been confirmed with survey data! • Method shows the ND can constrain many beam effects (Ihorn, collimator scraping, …)

33. Calibration of NuMI Flux Using MiniBooNE • NuMI n’s sprayed in all directions. • Kmn and pmn decays at off-axis angle: MiniBooNE q p, K p beam Decay Pipe ~110mrad to MiniBooNE • Opportunity to check the p/K ratio of yields off the target.