1. Accelerator Neutrino Oscillation Physics Lecture II
Deborah Harris
Fermilab
SUSSP
August 16, 2006

2. Outline of this Lecture
Introduction
What are the detector goals?
Particle Interactions in Matter
Detectors
Fully Active
Liquid Argon Time Projection
Cerenkov (covered mostly in Atmospheric n Lectures)
Sampling Detectors
Overview: Absorber and Readout
Steel/Lead Emulsion
Scintillator/Absorber
Steel-Scintillator
16 August 2006
Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II

3. For Each Detector All detector questions are far from answered!
Underlying principle
Example from real life
What do n events look like?
Quasi-elastic Charged Current
Inelastic Charged Current
Neutral Currents
Backgrounds
Neutrino Energy Reconstruction
What else do we want to know?
Warning: this lecture is a set of mini-lectures about different detector technologies…
All detector questions are far from answered!
16 August 2006
Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II

4. Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II
Detector Goals
Identify flavor of neutrino
Need charged current events!
Lepton Identification (e,m,t)
Measure neutrino energy
Charged Current Quasi-elastic Events
All you need is the lepton angle and energy
Corrections due to
p,n motion in nucleus
Everything Else
Need to measure energy of lepton and of X, where X is the hadronic shower, the extra pion(s) that is (are) made..
16 August 2006
Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II

5. Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II
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)
16 August 2006
Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II

6. Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II
Goals vs n Beams
Conventional Beams (nm, %ne)
Identify muon in final state
Identify electron in final state, subtract backgrounds
Energy regime: 0.4GeV to 17GeV
b beams (all ne )
Idenify muon or electron in final state
Energy regime: <1GeV for now
Neutrino Factories (nm, ne)
Identify lepton in final state
Measure Charge of that lepton!
Charge of outgoing lepton determines flavor of initial lepton
Energy regime: 5 to 50GeV n’s
16 August 2006
Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II

7. 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:
16 August 2006
Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II

8. 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
16 August 2006
Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II

9. Now for a n Factory… Note: as muon energy increases,
Assume you have a neutrino factory
which produces:
500 nm CC events per kton (200NC)
1000 ne CC events per kton (400NC)
Again, assuming 1% oscillation probability, but now the backgrounds are 10-4 (for all kinds of interactions), the signal efficiency is 50%, and again you have 15kton of detector (because it’s an easy detector to make)…
Background: ( .0001*2100(CC+NC))x15=3
Signal: (1000*.01*.5)x15=150, S/sqrt(B+S)=12
Get a “figure of merit” of 12 instead of 3 or 4…
which is like getting a 12s result instead of a 4s result, or being sensitive at 3s
to a 10 times smaller probability!
Note: as muon energy increases,
you get more n/kton for a n factory!
16 August 2006
Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II

10. Particles passing through material
Characteristic Length
Dependence
Electrons
Radiation length (Xo)
Log(E)
Hadrons
Interaction length (lINT)
Muons
dE/dx E
Taus
Decays first
gct=g87mm
Material Xo
(cm)
lINT(cm)
dE/dx
(MeV/cm)
Density
(g/cm3)
Liquid Argon 14
83.5
2.1
1.4
Water 37
83.6
2.0 1
Steel
1.76 17
11.4
7.87
Scintillator (CH) 42
~80
1.9
Lead
0.56
12.7
16 August 2006
Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II

11. Liquid Argon TPC (ICARUS)
Electronic Bubble chamber
Planes of wires (3mm pitch) widely separated (1.5m) 55K readout channels!
Very Pure Liquid Argon
Density: 1.4, Xo=14cm lINT =83cm
3.6x3.9x19.1m3 600 ton module (480fid)
16 August 2006
Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II

12. Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II
Half Module of ICARUS
View of the inner detector
16 August 2006
Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II

13. Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II
Liquid Argon TPC
Raw Data to Reconstructed Event
Because electrons can drift a long time (>1m!) in very pure liquid argon, this can be used to create an “electronic bubble chamber”
16 August 2006
Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II

14. Principle of Liquid Argon TPC
Readout planes: Q
Time
Edrift
Drift direction
Low noise Q-amplifier
Continuous waveform recording
High density
Non-destructive readout
Continuously sensitive
Self-triggering
Very good scintillator: T0
dE/dx(mip) = 2.1 MeV/cm
T=88K @ 1 bar
We≈24 eV
Wg≈20 eV
Charge recombination (mip)
@ E = 500 V/cm ≈ 40%
16 August 2006
Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II

15. Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II
dE/dx in Materials
Bethe-Bloch Equation
x in units of g/cm2
Energy Loss Only f(b)
Can be used for Particle ID in range of momentum
16 August 2006
Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II

16. Bethe-Bloch in practiceK+ e+ C µ+ B A AB BC K+ µ+
Question:
how would
This look different for a p→m event?
Run 939 Event 46
From a single event, see dE/dx versus momentum (range)
16 August 2006
Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II

17. Examples of Liquid Argon Events
Lots of information for every event…
e-, 9.5 GeV, pT=0.47 GeV/c
Primary t tag:
e decay
Exclusive t tag:
r decay
Primary Bkgd:
Beam ne
-  e- +  e +  _
CNGS  interaction, E=19 GeV
e-, 15 GeV, pT=1.16 GeV/c
Courtesy
André
Rubbia
Vertex: 10,2p,3n,2 ,1e-
CNGS e interaction, E=17 GeV
16 August 2006
Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II

18. p0 identification in Liquid Argon
1 π0 (MC)
One photon converts to 2 electrons before showering, so dE/dx for photons is higher…
Imaging provides ≈210-3 efficiency for single p0
cut
Preliminary
<dE/dx> MeV/cm
16 August 2006
Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II

19. Oustanding Issues Liquid Argon Time Projection Chamber
Do Simulations agree with data (known incoming particles)
Can a magnetic field be applied
Both could be answered in CERN test beam program
Is neutral current rejection that good?
How large can one module be made?
What is largest possible wire plane spacing?
Several R&D Efforts world-wide working to get >10kton detectors “on the mass shell”
16 August 2006
Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II

20. Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II
Cerenkov Light
As particles move faster than the speed of light in that medium, they emit a “shock wave” of light
particle
p (threshold) e
660keV m
137MeV p±
175MeV K
650MeV p
1300MeV
For water, n( nm)~1.33-6, so pthreshold≈1.3*mass
Threshold Angle: 42o
What is Threshold momentum for neutral pions?
16 August 2006
Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II

21. Event Reconstruction in Cerenkov Detector
Vertex Point fit: time of flight should be as sharp as possible
Define set of in-time tubes
Use Hough Transform to find rings
Look for rings until you’re done
Particle ID
Corrections to Vertex
Energy Reconstruction
Decay Electron Finding
16 August 2006
Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II

22. Particle ID Using Cerenkov Light
16 August 2006
Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II

23. Super-Kamiokande detector
50,000 ton water Cherenkov detector
(22.5 kton fiducial volume)
1000m underground (2700 m.w.e.)
11, inch PMTs for inner detector
1, inch PMTs for outer detector

24. Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II
16 August 2006
Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II

25. Single-Ring Energy Resolution
Tested in situ with LINAC at KEK
16 August 2006
Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II

26. Cerenkov with Mineral Oil
MiniBooNE detector:
Cerenkov with Mineral Oil
total volume: tons (6 m radius)
fiducial volume: 445 tons (5m radius)
1280 PMTs in detector at 5.5 m radius
10% photocathode coverage
240 PMTs in veto
electron ring
m ring
Events courtesy G. Zeller
16 August 2006
Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II

27. What about water Cerenkov at High (>1GeV) Energies???
Visible
Energy =
2GeV:
One Is e-
Is a p0
Courtesy Mark Messier: one is ne signal, one is p0 background
16 August 2006
Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II

28. s(En) of Water Cerenkov vs Enne CC
Reconstructed/True Energy nm CC NC
16 August 2006
Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II

29. Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II
Oustanding Issues
Cerenkov Detectors
What is largest vessel that can be made? (48mx58mx250m?)
What is highest energy regime that is possible, with better electronics,photo-detectors, etc?
Water Cerenkov clearly the cheapest per kton
16 August 2006
Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II

30. 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 Fermilab to Homestake Study
16 August 2006
Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II

31. From Fully Active to Sampling
Advantages to Sampling:
Cheaper readout costs
Fewer readout channels
Denser material can be used
More N, more interactions
Could combine emulsion with readout
Can use magnetized material!
Disadvantages to Sampling
Loss of information
Particle ID is harder (except emulsion for taus in final state)
16 August 2006
Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II

32. Sampling calorimeters
High Z materials:
mean smaller showers,
more compact detector
Finer transverse segmentation needed
Low Z materials:
more mass/X0 (more mass per instrumented plane)
Coarser transverse segmentation
“big” events (harsh fiducial cuts for containment)
Material
Xo (cm)
lINT
(cm)
Sampling (Xo)
Xo (g/cm2)
L.Argon 14
83.5
.2 (ICARUS) 20
Steel
1.76 17
1.4 (MINOS)
Scintillator 42
~80
.2 (NOnA) 40
Lead
0.56
.2 (OPERA) 6
16 August 2006
Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II

33. Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II
nt detection (OPERA)
Challenge: making a Fine-grained and massive detector to see kink when tau decays to something plus nt
16 August 2006
Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II

34. BRICK: 57 emulsion foils +56 interleaved Pb plates
Lead-Emulsion Target Pb
1 mm t 
12.5cm
10.2cm 
2 emulsion layers
(44 m thick)
glued onto a
200 m plastic base
10 X0’s
6.7m
8.3kg
BRICK: 57 emulsion foils +56 interleaved Pb plates
Wall prototype
Emulsion films (Fuji)
production rate ~8,000m2/month
(206,336 brick  ~150,000m2)
Lead plates (Pb + 2.5% Sb)
requirements:
low radioactivity level,emulsion compatibility,
constant and uniform thickness
52 x 64 bricks
Total target mass : 1766 t
16 August 2006
Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II

35. Particle ID in Emulsion
Grain density in emulsion is proportional to dE/dx
By measuring grain density
as a function of
the distance from
the stopping point,
particle identification
can be performed.
Test exposure (KEK) : 1.2 GeV/c pions and protons, 29 plates
pions
protons
Plots courtesy M. DeSerio
16 August 2006
Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II

36. One cannot live by Emulsion alone
Need to know when interaction has happened in a brick
Electronic detectors can be used to point back to which brick has a vertex
Take the brick out and scan it (don’t forget to put a new brick in!)
Question: what can you use for the “electronic detectors” that point back to the brick?
(Hint: you’ve used up most of the money you have to buy emulsion, you need something cheap that can point well anyway)
Passing-through tracks rejection
Connected tracks
with >= 2 segments
Track segments found in 8 consecutive plates
Vertex reconstructin
16 August 2006
Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II

37. Muon Spectrometer w/RPC
B= 1.55 T
base
slabs
coil
8.2 m
M ~ 950t
Drift tubes
12 Fe slabs
(5cm thick)
RPC’s
2 cm gaps
p/p < 20% ,
p < 50 GeV/c
 charge
Mis-id prob.
 0.1  0.3%
identification:
 > 95% (TT)
Inner Tracker:
11 planes of RPC’s
Precision tracker:
6 planes of drift tubes
diameter 38mm, length 8m
efficiency: 99%
space resolution: 300µm
21 bakelite RPC’s (2.9x1.1m2) / plane
(~1,500m2 / spectrometer)
pickup strips, pitch:
3.5cm (horizontal), 2.6cm (vertical)
RPC: gives digital information about track: has been suggested for use in several “huge mass steel detectors” (Monolith)
16 August 2006
Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II

38. Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II
nt detection (OPERA)
Detection Efficiency
16 August 2006
Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II

39. Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II
nt backgrounds
Cut on invariant mass of primary tracks
16 August 2006
Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II

40. nt events expected (OPERA)
m2 ( x 10-3 eV2)
Back-
ground
1.9
2.4
3.0
  µ
2.2
3.6
5.6
0.23
  e
2.7
4.3
6.7
  h
3.8
5.9
0.32
  3h
0.7
1.1
1.7
0.22
Total
8.0
12.8
19.9
1.0
Comparison:
4 nt events
over 0.34
background at
DONUT
.27kton
16 August 2006
Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II

41. Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II
Outstanding Issues
Emulsion Sampling
If LSND signature is oscillations, nt appearance will be much more important in the future
For future neutrino factory experiments, could study ne → nt
For either of these topics, need to understand if/how magnetic field can be made…
Any way to make this detector more massive?
16 August 2006
Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II

42. All Scintillator Detector
90 m
PVC extrusions
17m tallx17m widex90m long
3.87 cm transverse, 6 cm wide in beam direction (more light)
17.5 m long vs. 48 ft (less light)
All Liquid Scintillator
85% scintillator, 15% PVC
Previous design: inactive (particle board) plus active (scintillator) material, but was less efficient at rejecting backgrounds
APD readout
on TWO edges
To Build:
Glue Planes of Extrusions together
Rotate them from horizontal to vertical
Fill Extrusions with Liquid Scintillator
Each box gets a WLS fiber loop (bent at far end)
Instrument WLS fibers with Advanced PhotoDiodes
16 August 2006
Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II

43. 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)
16 August 2006
Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II

44. Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II
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
16 August 2006
Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II

45. Detector Volume, continued (courtesy K.McFarland)
Consider the Temple of the Olympian Zeus (right)…
17m tall, just like NOvA!
a bit over ½ the length
17m
It took 700 years to complete
Fortunately construction technology has improved
Left: Stoa toy Attaloy
120m
16 August 2006
Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II

46. Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II
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)
16 August 2006
Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II

47. All Scintillator m / e separation
electrons
electrons
muons
muons
Average number of hits per plane
Average pulse height 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
16 August 2006
Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II

48. Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II
Outstanding Issues
Fine Grained
Scintillator
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
16 August 2006
Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II

49. 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
16 August 2006
Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II

50. Simulated MINOS Events
CC Event e
CC Event
NC Event UZ VZ
3.5m
1.8m
2.3m
Courtesy Chris Smith, FNAL Seminar
Long muon track + hadronic activity at vertex
Short showering event, often diffuse
Short event with typical EM shower profile
En = Eshower + Pm
Shower energy resolution: 55%/√E
Muon momentum resolution: 6% range; 13% curvature
16 August 2006
Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II

51. Real Beam Events at MINOS (Far)
nm CC (left)
ne CC candidate
(bottom)
Remember:
2.5cm thick steel plates (~1.5X0)
(Courtesy C. Smith,
FNAL seminar)
U-Z View
V-Z View
X-Y View
T-Z View
PH-Z View
16 August 2006
Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II

52. 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?
16 August 2006
Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II

53. 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!
16 August 2006
Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II

54. Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II
Outstanding Issues
Steel/Scintillator
For Neutrino factory Application: what transverse and longitudinal segmentation is needed?
Any way to make this detector cheaper?
16 August 2006
Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II

55. Detector Scorecard
Detector
Technology
Largest Mass to Date (kton)
Event by Event Identification
+/-?
Ideal n
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 economical choice, but we need more to get to high energies and matter effects!
16 August 2006
Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II

56. Oscillation Experiments: Detectors past, present, and near future…
Exp’t
Energy
(GeV)
Detector Technology
K2K
1.4
Water Cerenkov
MINOS
2-6
Steel Scintillator
OPERA
15-25
Emulsion-Lead
ICARUS
Liquid Argon TPC
T2K
0.7
NOvA 2
Segmented Scintillator
OPERA
e-, 15 GeV, pT=1.16 GeV
Vertex: 10,2p,3n,2 ,1e-
ICARUS
Super-K
ne+A→p p+
p- e-
nm CC
ne CC
NOvA
MINOS
16 August 2006
Deborah Harris Accelerator Neutrino Oscillation Physics Lecture II