High Energy Neutrino Detectors Day 2

1
High Energy Neutrino DetectorsDay 2

• Deborah Harris
• Fermilab
• Nufact05 Summer Institute
• June 14-15, 2005

2
Making a Neutrino Beam

• Conventional Beam
• Beta Beam
• Neutrino Factory

For each of these beams, n flux (F) is related to
boost of parent particle (g)
3
Next Step in this field appearance!

• Q13 determines
• If well 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
• Detector-related backgrounds

4
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
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 400.0025NC)x517.5 Sign
al (1000.01.5)x525, S/sqrt(BS)3.8
Background ( 5.3 ne 400.005NC)x1552.5 Sign
al (1000.01.3)x1545, S/sqrt(BS)4.6
6
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
7
Scintillator Events (2GeV)
nm A -gt p m-
neA?p p p- e-
n A -gt p 3p p0 n
Particle ID particularly fuzzy es
long track, not fuzzy (m) gaps in tracks (
p0 ?) large energy deposition
(proton?)
One unit is 4.9 cm (horizontal) 4.0 cm (vertical)
8
Detector Volume

• Scaling detector volume is notso 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
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

• Consider theStoa toy Attaloy

10
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 nes (for the
  case of an Off Axis beam)

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

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

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
(simulated) Events at MINOS
2.4GeV nmCC
25GeV nmCC
8.5GeV neCC
10GeV nNC
15
Real Beam Events at MINOS (Far)
NC or ne CC candidate
Remember 2.5cm thicksteel plates(1.5X0)
nm CC candidate
nm CC candidate
16
Steel Scintillator Response
Response measured in CERN test beam using a
MINI-MINOS (1mx1m)

• Provides calibration information
• Test of MC simulation of low energy hadronic
  interactions
• Question why might EM response be higher than
  hadronic response?

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 dont deposit energy
  nearby, and often just get absorbed!

18
Backgrounds in n Factories
19
Detector-Dependence

• The denser the detector, the more likely the
  meson in the hadronic shower will interact before
  decaying

20
Outstanding Issues
Steel/Scintillator

• For Neutrino factory Application what
  transverse and longitudinal segmentation is
  needed?
• Any way to make this detector cheaper?

21
Conclusions
Detector Scorecard

• There are huge detector demands on the next
  generation of detectors
• Sizesignal 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!

22
Water Cerenkov at High (gt1GeV) Energies
Courtesy Mark Messier one is ne signal, one is
p0 background
23
s(En) of Water Cerenkov vs En
neCC
nmCC
nNC
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