Transcript About Detectors 

About  Detectors
Alberto Marchionni, Fermilab
 Next challenges in neutrino physics call for larger and specialized
detectors
 How to extrapolate from past & present neutrino detectors to what
we need for the future ones ?
 beam optimization (superbeams, off-axis,  factories,…) is a
key element to simplify the detectors
 not every detector technology of the past is fit for future
applications
 Water Cherenkov detectors
 Sampling, tracking calorimeters
 Liquid Argon TPC’s
 Conclusions
The Physics Roadmap
 The next generation of neutrino experiments will focus
on  to e transitions to find out about
 13
 normal or inverted mass hierarchy
 possibility of CP violation in the leptonic sector
 We want to be sensitive to oscillation probabilities down
to few10-3
 Experiments, at least in a first phase, will be statistics
limited
Beam-Detector Interactions
 At which distance and which energy ?
 flux  1/L2
 oscillation probability  sin2(1.27 m2L/E)
 Which energy ? 1st, 2nd,… oscillation maximum ?
 dependence of  cross section on energy
 sensitivity to matter effects
 A limit: how many protons can I get ?
 Neutrino beam optimization to reduce background
 use a narrow energy beam (off-axis concept) to reduce NC
background and beam e intrinsic background
 use a neutrino factory and look for wrong sign muons
 use of beta-beams
 sensible choices will make the detector easier to build and
operate
Different strategies
m2=2.510-3 eV2
1
2
3
L(km)/n
(GeV) (GeV) (GeV)
300
0.61
0.20
0.12
800
1.62
0.54
0.32
1200
2.43
0.81
0.49
n=oscillation peak
E < 1 GeV (KEK/JPARC to
SuperK, CERN to Frejus
0.3 < E < 3 GeV
(NuMI off-axis)
0.5< E < 5 GeV
(C2GT, BNL to ?)
 JPARC
Different detectors 
• mostly quasi-elastic, 1 
 NuMI
• few ’s, range out
Scaling violations
Florence Dome,
span 42 m,
masonry structure
Oita sports park
“Big Eye” dome,
span 274 m, steel
structure
Millennium Dome,
Greenwich, London,
span 365 m, cable
structure
Super-Kamiokande
50,000 ton water Cherenkov detector
(22.5 kton fiducial volume)
39 m
Hyper-Kamiokande
~1,000 kt
Good for atm. 
proton decay
L=500 m
10 subdetectors
Candidate site in Kamioka
MINOS Far Detector
 2 sections, each 15m long
 8m Octagonal Tracking Calorimeter
 486 layers of 2.54cm Fe
 4cm wide solid scintillator strips with WLS
fiber readout
 25,800 m2 active
detector planes
 Magnet coil provides
<B>  1.3T
 5.4kt total mass
 Fully loaded cost
~$6 M/kton
MINOS Detector Technology
Detector module with
20 scintillator strips
MUX boxes route 8 (1 in Near
Detector) fibers to one MAPMT
pixel
e Interactions in MINOS?
NC interaction
Detector Granularity:
•Longitudinal: 1.5X0
•Transverse: ~RM
 NC interactions
• energy distributed over
a ‘large’ volume
 e CC interactions (low y)
• electromagnetic shower
short and narrow
• most of the energy in a
narrow cluster
energy
e CC, Etot = 3 GeV
How to improve e signal/background:
choice of the beam
 spectrum
NC (visible energy),
no rejection
e background
e (|Ue3|2 = 0.01)
NuMI low
energy beam
NuMI off-axis beam
These neutrinos contribute
to background, but not to
the signal
A Detector for NuMI off-axis
 Physics requirements
 very large mass
 identify with high efficiency e charged interactions
 good energy resolution to reject e’s from background sources
 e background has a broader energy spectrum than the
potential signal
 provide adequate rejection against  NC and CC backgrounds
 e/0 separation
• fine longitudinal segmentation, smaller than X0
• fine transverse segmentation, finer than the typical
spatial separation of the 2 ’s from 0 decay
 e/,h separation (electrons appears as “fuzzy” tracks)
 optimized for the neutrino energy range of 1 to 3 GeV
 detector on surface, must be able to handle raw rate and
background from cosmic rays
 fine granularity, low/medium Z tracking calorimeter
Towards a detector choice
 Design challenges
 large fiducial mass at low unit cost
 aim to reduce the cost/kton by ~3 with respect to MINOS
 fine granularity, low/medium Z tracking calorimeter
 operating in a relatively remote location: rugged, robust, low
level of upkeep and maintenance
 A monolithic detector as tracking calorimeter ?
 Large ( 10 kTon) LAr TPC, as evolution from the ICARUS
design
 A sampling detector as tracking calorimeter ?
 several examples on a smaller scale in the past: CHARM,
CHARMII, ….
 choice of absorber structure and active detector modules
Detectors under consideration
for NuMI off-axis
 A sampling, tracking calorimeter detector of 50 kton
 proposed absorber is manufactured wood sheets, either
particleboard (from wood “sawdust”) or Oriented Strand Board
(from wood chips)
• structural strength
• can be produced in sheets of sizes up to ~ 2.4m8.5m2.5cm
• density ~ 0.7 g/cm3
• availability of industrial strength fastening systems, high
strength adhesives, cartridge loaded screw guns,…
• low cost: ~ $290/ton, production plants in Minnesota
 proposed active detector elements
• Liquid scintillator as the baseline technology
• Glass Resistive Plate Chambers as backup
Liquid scintillator detector
 50 kton sampling calorimeter detector, comprised of 42 kton of
wood particleboard as absorber and 7 kton of mineral-oil based
liquid scintillator as active detector, contained in segmented PVC
extrusions of 1 kton total mass
 1/3 X0 longitudinal granularity, 4 cm transverse granularity
 made up of 750 planes, 29.3 m wide, 14.6 m high and 22.9 cm
thick, arranged to provide alternating horizontal and vertical views,
for a total length of 171.5 m
 the liquid scintillator is contained in segmented titanium dioxide
loaded PVC extrusions 14.6 m long, 1.2 m wide and 2.86 cm thick,
with 4 cm transverse segmentation
 the scintillation light in each cell will be collected by a looped 0.8
mm  wavelength-shifting plastic fiber
 light from both ends of the fiber will be directed to a single pixel
on an avalanche photodiode (APD)
 540,000 analog readout channels
Assembly of the liquid
scintillator detector 29.3 m
Stack:
size 48’8’9”
weight ~ 5 tons
Each stack is equivalent to 7
layers of particle board and
one layer of PVC extrusion
containing liquid scintillator
48’
8’
The detector consists of
750 planes. Each plane is
made out of 12 stacks.
Readout of the liquid scintillator
detector
The APD readout combines
the advantages over PMT of
lower cost and much higher
quantum efficiency
Hamamatsu 32channel APD array
Pixel size
1.81.8 mm2
Quantum efficiency
Sizeable number of
photoelectrons/MIP:
~30 photoelectrons
for an interaction at
the far end of a
looped fiber.
With FNAL SVX4
electronics and APD
cooling expect
S/N ~ 5:1
Manifold to
collect fibers
from the ends
of scintillator
cells to an
optical
connector
1
APD
0.8
WLS fiber
Emission spectra
for L=0.5-16 m
0.6
0.4
0.2
w
PMT
0
450
500
550
600
Wavelength (nm)
650
Glass RPC detector
 50 kton detector made of 1200 modules, stacked in an array made
of 75 planes along the beam direction, each plane being 2 modules
wide and 8 high
 Each module, 8.5m2.4m2.6m with a weight of 42 tons,
consists of 12 vertical planes of absorber interleaved with a detector
unit consisting of a double plane of RPC’s
Aluminum
end-frames
5 planes of stacked
 Walls of modules are supported
from the floor and are not connected
to each other
 Modules within each wall are
interlocked with the help of corner
Steel end-frames
blocks as used in standard shipping
modules
container
Glass RPC detector units
 The low rate environment of a neutrino experiment makes it
possible to use glass RPC’s with strip readout as active detectors
 They can provide 2-dimensional position information from every
plane of detectors
 Very large induced signals processed by simple discriminators
 measurement of the event limited to recording of “hits”
 RPC chambers, 2.8442.425 m2, are composed of 2 parallel glass
electrodes, 3 mm thick, kept 2 mm apart by Noryl spacers placed
every 15 cm
 2 planes of RPC’s, each made of 3 RPC’s, are sandwiched between
2 particleboards, used as readout boards
 Both surfaces of both particleboards are laminated with thin copper foil. Foils
on inner surfaces are cut into strips
 Each detector unit has 192 vertical strips and 64 horizontal ones
 horizontal strips are 3.7 cm wide, vertical ones 4.34 cm wide
 3.7106 digital channels
Electron/ appearance
RPC detector simulation
Fuzzy track = electron
Clean track = muon
NC background
RPC detector simulation
NC - 0 - 2 tracks
gap
Simulation results
 41020 pot/yr, 5 year run
 50 kton RPC detector, 85% fiducial mass
 positioned at a distance=735 km, offset=10 km
 m2=2.510-3, sin2(213)=0.1, no matter effects or CP included
Signal
Backgrounds
Beam e
NC
CC
Reconstructed
events before cuts
639.4
477.2
6899.8
10110.7
After cuts
214.5
24.6
21.9
3.1
Efficiency/Bckg
fraction
33.5%
5.210-2 3.210-3 3.110-4
 Figure of merit: S/B=214.5/49.6=30.4
ICARUS: a Liquid
Argon Imaging
Detector
light
Ionizing Track
Drifting
e-
 Working principle:
 Ionization chamber filled with
LAr, equipped with
sophisticated electronic readout system (TPC) for 3D
imaging reconstruction,
calorimetric measurement,
particle ID.
 Absolute timing definition and
internal trigger from LAr
scintillation light detection
A. Rubbia
Neutrino physics with a Large LArTPC
 The ideal detector for a neutrino factory/off-axis a’ la NuMI
 Excellent pattern recognition capabilities and energy
determination
 High efficiency for electron identification and excellent e/0
rejection
  identification via kinematic reconstruction
 lepton charge determination if in a magnetic field
ICARUS T300 Prototype
LAr Cryostat (half-module)
4m
4m
20 m
View of the inner detector
A large magnetized LAr TPC
LANNDD: Liquid Argon Neutrino and Nucleon Decay Detector
F. Sergiampietri, NuFact’01
Coil
Iron yoke
Field shaping
electrodes
Cathode
Wire
chamber
Cryostat
 = 40 m
H = 40 m
85 m drifts
70 kTon active LAr mass
Detector chambers structure
F. Sergiampietri, NuFact’01
 # wire chambers: 4
• CH1,CH4 W=26.8 m, H=40 m
• CH2,CH3 W=39.2m, H=40 m
 readout planes/chamber: 4
• 2 @ 0o, 2 @ 90o
• stainless steel 100m wires at
a 3 mm pitch
• screen-grid planes/chamber: 3
 total # wires (channels): 194648
 # cathode planes: 5
R&D on a Large LAr TPC
 R&D items to face
 Engineering of a large cryostat
 Engineering of wire chambers
 HV feedthroughs up to 250 kV
 Argon purity
 Working conditions under high
hydrostatic pressure
HV=200-250 kV
Tmax drift=3.1-3.6 ms
My personal conclusions
 Different “baselines & energies” have different detector requirements
 given the importance of the physics measurements, which could possibly
lead to the discovery of CP violation in the leptonic sector, measurements
with different detectors are important and different baselines are
somewhat complementary
Water Cherenkov detectors are a well established technology
 a factor 20 increase in mass is being considered
 A large effort is underway to develop large (~50 kton) sampling,
tracking calorimeters
 R&D is crucial to verify the choice of technology
 Impressive results from ICARUS 300 ton prototype
 LAr technology is mature to proceed with the construction of a few kton detector
 LAr technology could be considered for 10 kton detector
 Lots of room for new, clever ideas, … but we need to move up to be ready to
fully exploit the facilities that we have now
 we are in the lucky situation where a series of upgrades in
beamlines/detectors could lead us to important physics discoveries