High Energy Neutrino Detectors Day 2 Deborah Harris Fermilab Nufact’05 Summer Institute June 14-15, 2005

Deborah Harris High Energy Neutrino Detectors Making a Neutrino Beam Conventional Beam Beta Beam Neutrino Factory For each of these beams, n flux (Φ) is related to boost of parent particle (g) 14-15 June 2005 Deborah Harris High Energy Neutrino Detectors

Next Step in this field: appearance! Q13 determines If we’ll ever determine the mass hierarchy The size of CP violation How do backgrounds enter? Conventional beams: nm → ne Already some ne in the beam Detector-related backgrounds: Neutrino Factories: No beam-related backgrounds for ne→nm 14-15 June 2005 Deborah Harris High Energy Neutrino Detectors

Deborah Harris High Energy Neutrino Detectors Scintillator + Wood Alternating horizontal and vertical scintillator planes Passive material: particle Board (density .6 - .7 g/cm3) Sampling: 1/3 rad. length readout 15 m 180 m readout readout 15 m 15 m 885 planes = detector 9.4 tons 48 ft Scintillator modules 8 ft 8 ft 14-15 June 2005 Deborah Harris High Energy Neutrino Detectors

Why do detector efficiencies and background rejection levels matter? Assume you have a convenional neutrino beamline which produces: 1000 nm CC events per kton (400NC events) 5 ne CC events per kton Which detector does better (assume 1% nm-ne oscillation probability) 5 kton of 50% efficient for ne 0.25% acceptance for NC 15kton of 30% efficient for ne 0.5% acceptance for NC events? Background: ( 5*.5 ne + 400*.0025NC)x5=17.5 Signal: (1000*.01*.5)x5=25, S/sqrt(B+S)=3.8 Background: ( 5*.3 ne + 400*.005NC)x15=52.5 Signal: (1000*.01*.3)x15=45, S/sqrt(B+S)=4.6 14-15 June 2005 Deborah Harris High Energy Neutrino Detectors

All Scintillator Detector Similar PVC extrusions thicker cells along the beam 4.5 cm vs. 2.56 cm (more light) Longer extrusions 17.5 m long vs. 48 ft (less light) 32 cells wide vs. 30 cells All Liquid Scintillator 85% scintillator, 15% PVC ~Same price implies a detector with ½ the mass 17.5 m 90 m 17.5 m APD readout on TWO edges Detector is wider & taller, but shorter along the beam No crack down the center Least light areas are at the left And bottom edges 14-15 June 2005 Deborah Harris High Energy Neutrino Detectors

Scintillator Events (2GeV) nm + A -> p +m- ne+A→p p+ p- e- n + A -> p + 3p± + p0 + n Particle ID: particularly “fuzzy” e’s long track, not fuzzy (m) gaps in tracks ( p0 ?) large energy deposition (proton?) One unit is 4.9 cm (horizontal) 4.0 cm (vertical) 14-15 June 2005 Deborah Harris High Energy Neutrino Detectors

Deborah Harris High Energy Neutrino Detectors Detector Volume Scaling detector volume is not so trivial At 30kt NOvA is about the same mass as BaBar, CDF, Dzero, CMS and ATLAS combined… want monolithic, manufacturabile structures seek scaling as surface rather than volume if possible Figure courtesy J.Cooper 14-15 June 2005 Deborah Harris High Energy Neutrino Detectors

Detector Volume, cont. (courtesy K.McFarland) Consider the Temple of the Olympian Zeus… 17m tall, just like NOvA! a bit over ½ the length It took 700 years to complete Fortunately construction technology has improved 120m Consider the Stoa toy Attaloy … 14-15 June 2005 Deborah Harris High Energy Neutrino Detectors

Deborah Harris High Energy Neutrino Detectors Energy Resolution Energy Resolution For ne CC events with a found electron track (about 85%), the energy resolution is 10% / sqrt(E) Measured – true energy divided by square root of true energy This helps reduce the NC and nm CC backgrounds since they do not have the same narrow energy distribution of the oscillated ne’s (for the case of an Off Axis beam) 14-15 June 2005 Deborah Harris High Energy Neutrino Detectors

All Scintillator m / e separation electrons electrons muons muons Average pulse height per plane Average number of hits per plane This is what it means to have a “fuzzy” track Extra hits, extra pulse height Clearly nm CC are separable from ne CC 14-15 June 2005 Deborah Harris High Energy Neutrino Detectors

Outstanding Issues Fine Grained Scintillator/Something Sampling How cheaply can this be made? Do you need any passive absorber? What is best choice for readout? Must have confidence in ability to reduce Neutral Current Backgrounds 14-15 June 2005 Deborah Harris High Energy Neutrino Detectors

Steel/Scintillator Detector (MINOS) 8m octagon steel & scintillator calorimeter Sampling every 2.54 cm 4cm wide strips of scintillator 5.4 kton total mass 486 planes of scintillator 95,000 strips 14-15 June 2005 Deborah Harris High Energy Neutrino Detectors

(simulated) Events at MINOS 2.4GeV nmCC 25GeV nmCC 8.5GeV neCC 10GeV nNC 14-15 June 2005 Deborah Harris High Energy Neutrino Detectors

Real Beam Events at MINOS (Far) NC or ne CC candidate Remember: 2.5cm thick steel plates (~1.5X0) nm CC candidate nm CC candidate 14-15 June 2005 Deborah Harris High Energy Neutrino Detectors

Steel Scintillator Response Response measured in CERN test beam using a MINI-MINOS (1mx1m) MC expectation Provides calibration information Test of MC simulation of low energy hadronic interactions Question: why might EM response be higher than hadronic response? 14-15 June 2005 Deborah Harris High Energy Neutrino Detectors

Hadron/Electron Comparison Electromagnetic response: photons always convert to electrons which deposit all their energy nearby Hadronic response: when neutrons are created in the shower, they don’t deposit energy nearby, and often just get absorbed! 14-15 June 2005 Deborah Harris High Energy Neutrino Detectors

Backgrounds in n Factories 14-15 June 2005 Deborah Harris High Energy Neutrino Detectors

Deborah Harris High Energy Neutrino Detectors Detector-Dependence The denser the detector, the more likely the meson in the hadronic shower will interact before decaying… 14-15 June 2005 Deborah Harris High Energy Neutrino Detectors

Deborah Harris High Energy Neutrino Detectors Outstanding Issues Steel/Scintillator For Neutrino factory Application: what transverse and longitudinal segmentation is needed? Any way to make this detector cheaper? 14-15 June 2005 Deborah Harris High Energy Neutrino Detectors

Conclusions Detector Scorecard Technology Largest Mass to Date (kton) Event by Event Identification +/-? Ideal Neutrino Energy Range ne nm nt LAR TPC 0.6  Not yet huge Water Cerenkov 50 <2GeV Emulsion/Pb/Fe 0.27 >.5GeV Scintillator++ 1 or less Steel/Scint. 5.4 There are huge detector demands on the next generation of detectors Size*signal efficiency Background rejection (NC) “Ability to do other physics” Water Cerenkov the most popular choice for next generation experiments, but we must keep working on ways to do better at high neutrino energies! 14-15 June 2005 Deborah Harris High Energy Neutrino Detectors

Water Cerenkov at High (>1GeV) Energies Courtesy Mark Messier: one is ne signal, one is p0 background 14-15 June 2005 Deborah Harris High Energy Neutrino Detectors

s(En) of Water Cerenkov vs En neCC nmCC nNC 14-15 June 2005 Deborah Harris High Energy Neutrino Detectors

e(Erecon) for Water Cerenkov Probability of ne CC Giving 1 e-like ring Reconstructed Energy (GeV) Probability of nm CC Giving 1 m-like ring Reconstructed Energy (GeV) Probability of n NC Giving 1 e-like ring Giving 1 m-like ring Reconstructed Energy (GeV) Again, courtesy Mark Messier, for FeHo Study 14-15 June 2005 Deborah Harris High Energy Neutrino Detectors