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

2. 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

3. 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

4. Deborah Harris High Energy Neutrino Detectors
Scintillator + Wood
Alternating horizontal and vertical scintillator planes
Passive material: particle Board (density 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

5. 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 *.0025NC)x5=17.5
Signal: (1000*.01*.5)x5=25, S/sqrt(B+S)=3.8
Background: ( 5*.3 ne *.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

6. All Scintillator Detector
Similar PVC extrusions
thicker cells along the beam
4.5 cm vs 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

7. 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

8. 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

9. 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

10. 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

11. 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

12. 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

13. 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

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

15. 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

16. 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

17. 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

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

19. 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

20. 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

21. 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

22. 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

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

24. 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