Conventional Neutrino Beams Day 2

1. Conventional Neutrino BeamsDay 2 Deborah Harris NuFact05 Summer Institute Anacapri, Italy June 12-13, 2005

2. Using Pions to make Neutrinos • Major Components: • Proton Beam • Pion Production Target • Focusing System • Decay Region • Absorber • Shielding… Most nm’s from 2-body decays: p+→m+nm K+→m+nm Most ne’s from 3-body decays: m+→e+nenm K+→p0e+ne n energy is only function of np angle and p energy Deborah Harris, Conventional Neutrino Beamlines

3. Questions From Yesterday • What happens to the nm event rate if you change the horn current? (0, 100kA, and 200kA shown) At 735km At 1km Visible Energy (GeV) Visible Energy (GeV) • Corrolary: What happens if you lower the horn current by 15kAmps and move the target back 10cm? Deborah Harris, Conventional Neutrino Beamlines

4. How can you measure the beam performance? • Primary Proton Beam Measurements • Remnant Proton Measurements • Tales from the front line: NuMI and the target leak • Muon Measurements • 7o muon spectrometer (MiniBooNE) • “Range stack” Muon Monitor system (MINOS) Pions+… Neutrinos protons Muons+… Deborah Harris, Conventional Neutrino Beamlines

5. Neutrino Beamline Instrumentation • Proton Beam • Number of Protons on Target • Position and angle • Spot size of beam on target • Proton Losses before target • Target • Position and angle • Is it intact? • Temperature • Horns • Position and angle • Current • Is it intact? • Temperature • Absorber • Temperature Deborah Harris, Conventional Neutrino Beamlines

6. Primary Beam Measurements • Knowing proton position is important: want to hit the center of the target • Knowing angle is important: if proton beam is at angle, the n beam comes out at an angle as well. • Two ways to measure proton position: • Non-interfering (use induction) • Interfering (secondary emission monitors) Deborah Harris, Conventional Neutrino Beamlines

7. Proton Position Measurements • Beam Position Monitors: • Beam pipe with two isolatedplates (A and B) • When protons go through, charge is induced on both plates • Position=Gain*(A-B)/(A+B) • Benefits: does not interfere with proton beam • Deficits: can be noisy, can have worse resolutionat low proton intensity, gives no shape information… Deborah Harris, Conventional Neutrino Beamlines

8. Secondary Emission Monitors • Secondary Emission: when charged particles go through metal foil, electrons can be kicked off • By applying a small electric field you can drift the electrons away from the foil (also need high vacuum for this!). • Now imagine a row of very thin foils oriented in horizontal and vertical direction • This gives not only a mean position, but also gives you the information of the shape • Benefits: shape and mean position • Deficits: putting matter in beam (but can be as low as 10-5lint) Deborah Harris, Conventional Neutrino Beamlines

9. Tales from the front: NUMI, Dec. 4 2005 Deborah Harris, Conventional Neutrino Beamlines

10. What about seeing the Protons at the end of the decay pipe? • Proton spot size at end of pipe is large: cannot just put in a new secondary position monitor • Proton rates are now very intense: can use ionization chambers, but they must be very resistant to radiation damage, and can be low gain • Question: what else makes it down to the end of the decay pipe? • Muons from pion decay • Undecayed pions • Secondary shower particles Deborah Harris, Conventional Neutrino Beamlines

11. Seeing protons at end of pipe No target in the way Target in the way For most beamlines, this “hadron monitor” is really a proton monitor: it tells you about the protons and the target, but not about how well you are making neutrinos Deborah Harris, Conventional Neutrino Beamlines

12. Lesson Learned: be prepared for disasters… Look at what is between targetand baffle by shooting protons there! • Leaky Target at NuMI • the target has pipes around it that carry water to cool it • On March 23, discovered a leak: speculate the target surrounded by water… • Use Hadron Monitor to verify that water was there, and to check that it hasn’t reappeared since we solved the problem… Deborah Harris, Conventional Neutrino Beamlines

13. Monitors to Study n Beam (MINOS) m+ m+ nm m+ m+ p p+ m+ m+ Hadron Monitor: sees uninteracted protons after decay pipe Muon Monitors: 3 different depths means three different muon momentum spectra Deborah Harris, Conventional Neutrino Beamlines

14. Getting to Neutrino Spectrum from Muon Spectrum (MINOS) • As you get to higher muon energies, you are looking at higher pion energies…which in turn mean higher neutrino energies… Deborah Harris, Conventional Neutrino Beamlines

15. Muon Monitors in Different Energy Neutrino Beams • By looking at the rates in the three different muon detectors, can see how the energy distributions of the muons changes • Can study neutrino fluxes by moving the target and seeing how you make more high energy neutrinos the farther back you move the target • Can study fluxes by changing the horn current and see how you make more low energy neutrinos as you increaste the horn current. Graphs courtesy S. Kopp Deborah Harris, Conventional Neutrino Beamlines

16. What else you can do with muons:Measure K/p ratio in Beam • ne’s from muon decay constrained by nm spectrum (since they are part of the same channel) • Kaons have no such constraint • Remember problem set: to get the ne /nm Ratio you would also need to know the K/p production ratio (and focusing differences) Any way this can be measured in the beam? Beam too hot to add Cerenkov counters to get track/track information Think 2-body decay kinematics: Center of Mass Lab Frame Deborah Harris, Conventional Neutrino Beamlines

17. Example from MiniBooNE Backgrounds from muons that scatter in the dirt/collimator • By adding collimator and spectrometer at 7o, they will measure • p/K ratio from difference in peaks • K/KL ratio from m+ versus m- Deborah Harris, Conventional Neutrino Beamlines

18. Hadron Production Measurements • Measuring relative rates in muon monitors are a great handle on neutrino production but… • Delta-ray production means the absolute signal on the detector as a function of muon flux is very hard to predict….so these measurements can only provide relative flux information • Hadron Production Measurements: getting to an absolute flux prediction Deborah Harris, Conventional Neutrino Beamlines

19. Measuring Mesons as they leave Target Particle Production Experiments: HARP (at CERN) took data with K2K, MiniBooNE targets MIPP (at Fermilab) will take data With MINOS target Can take data with small samples, But need to then model also the Particle showering in the target… MIPP Running now Will take data with NuMI/MINOS target And also 1-2% targets Deborah Harris, Conventional Neutrino Beamlines

20. Uncertainties due to Hadron Production • MINOS example: • 10-30% uncertainties in absolute rate • 2-10% uncertainties in far/near comparison Messier, Ely 2004 Deborah Harris, Conventional Neutrino Beamlines

21. But haven’t people measured particle production before? MINOS Beam: What is not the same: Target Material Proton Energy Proton angular distribution Target length Deborah Harris, Conventional Neutrino Beamlines

22. Measuring p angular distribution in real beamline • K2K Gas Cerenkov counter: measures angular distribution of Pions as function of momentum • Located right after horns • Works for pions above 2GeV Deborah Harris, Conventional Neutrino Beamlines

23. Measuring p angular distribution in real beamline Deborah Harris, Conventional Neutrino Beamlines

24. Conventional Neutrino Beam Summary • Major Components: • Proton Beam • Production Target • Focusing System • Decay Region • Shielding • Monitoring Ways to Understand n Flux: Hadron Production Proton Beam measurements Pion Measurements Muon Measurements at angles vs momentum at 0o versus shielding Deborah Harris, Conventional Neutrino Beamlines