Download - How to Build a Neutrino Oscillations Detector - Why MINOS is like it is! Alfons Weber March 2005
How to Build a Neutrino Oscillations Detector
-Why MINOS is like it is!
Alfons Weber
March 2005
March 2005 A. Weber
MINOS Experiment 2
Neutrino Oscillations• MINOS is a long baseline Neutrino Oscillation
Experiment– What do we want to measure?
– We want to see, how one type of Neutrino transforms itself into another.
– There is a characteristic pattern, if this is transformation is due to “neutrino mass eigenstates”
• Simplified two neutrino scenario:
22 2 1.27
( ) 1 sin (2 )sinm L
PE
1
2
cos sin
sin cos
or 1 2,
March 2005 A. Weber
MINOS Experiment 3
March 2005 A. Weber
MINOS Experiment 4
NuMI & The Main Injector Fermilab Main Injector:
120 GeV protons 2.5 x 1013 protons/pulse 1.9 sec rep rate (~8 sec spill) 0.25 MW
NuMI Beam:
Graphite target Two magnetic horns 675 m. vac. decay pipe hadron absorber designed for 4 x 1013 ppp
Beam Monitoring:
muon detectors hadron detectors + Near Detector !
March 2005 A. Weber
MINOS Experiment 5
NuMI Beam Layout
March 2005 A. Weber
MINOS Experiment 6
120 GeV primary Main Injector beamTarget readily movable in beam direction2-horn beam adjusts for variable energy ranges675 meter decay pipe for decay
Neutrino Production
March 2005 A. Weber
MINOS Experiment 7
MINOS Physics Reach
νµ CC Events/year(with no oscillations)
Low Medium High 1,600 4300 9250
Nominal Beam Configurations Intense beam from FNAL- initially 2.5 x 1020 p.o.t./year, (being commisioned now !!)
Beam spectra: M. Messier
March 2005 A. Weber
MINOS Experiment 8
• Charge current– electron
– muon
– tau
– Can measure neutrino energy
• Neutral Current– electron
– muon
– tau
μ ν μ
hadrons
5 m
ν μ
hadrons
ν μ
1.5 m
Neutrino Interactions
March 2005 A. Weber
MINOS Experiment 9
Oscillation Pattern2
2 2 1.27( ) 1 sin (2 )sin
m LP
E
2 3 23 10m eV
735 kmL
No Effect!
measures m2
Smeared by resolution
P ~ 1/2
2 Em
L
March 2005 A. Weber
MINOS Experiment 10
MINOS Analysis• Select νμ charge current events
and reconstruct neutrino energy
Energy resolution:
Compare energy spectrum in near and far detector
Measure Δm2 and sin22θ
• Look for appearance of νe
beam & NC contamination
hEEE
range, B field calorimetric
EEE
pp
hh /%60/
%10/
Δm2
sin22θ
March 2005 A. Weber
MINOS Experiment 11
Where should the Experiment be?
• Δm2= 0.002-0.003 eV2 (from SK)• In oscillation Minimum
L/E = 400 - 800 km / GeV• Larger distance shorter distance• High energy low energy• Flux ~ 1/L2
• Cross section ~ E • Event size ~ E
March 2005 A. Weber
MINOS Experiment 12
• NuMI beam travels 735 km to Soudan (MN)
• Sagitta:10 km
• 1 km wide at destination
The MINOS Experiment
March 2005 A. Weber
MINOS Experiment 13
March 2005 A. Weber
MINOS Experiment 14
Detector
• Design requirements– High Mass
– High segmentation– Affordable
March 2005 A. Weber
MINOS Experiment 15
MINOS Detectors• There are 3 MINOS Detectors
– Near Detector @ FNAL (ND)
– Far Detector @ Soudan (FD)
– Calibration Detector @ CERN (CalDet)
• Magnetised steel scintillator tracking calorimeter– Alternating planes of steel and scintillator strips
5.4 kton
12 ton0.9 kton
March 2005 A. Weber
MINOS Experiment 16
Soudan Underground Laboratory
• former iron mine, now a state park, – home of: Soudan-1 & 2 , CDMS-II , and MINOS expts
March 2005 A. Weber
MINOS Experiment 17
MINOS Construction Challenge
March 2005 A. Weber
MINOS Experiment 18
Bottom steel plane layer
Top steel plane layerScintillator planeOrientations alternate
90o in successive planes
2-m wide, 0.5-inch thicksteel plates
MINOS Plane
March 2005 A. Weber
MINOS Experiment 19
Far Detector• In old iron mine• Was already there
– Soudan 1 & 2
• Right distance from FNAL
March 2005 A. Weber
MINOS Experiment 20
8 m
Scintillator Module
WL
S Fi
bers
WL
S Fi
bers
Optical Connector
Optical Connector
Optical Connector
Optical Connector
Cle
ar F
iber
Rib
bon
Cab
le (
2-6
m)
MultiplexBox
MultiplexBox
PMTs
Con
nect
ion
to
elec
tron
ics
Con
nect
ion
to
elec
tron
ics
MINOS Scintillator Module
• 4-8m scintillator modules
• 24-28 strips
• double sided readout
• multi anode PMTs (16/64)
March 2005 A. Weber
MINOS Experiment 21
PMT• Light is detected by
multi-anode PMTs– 230x 64-pixel in ND
– 1500x 16-pixel in FD
• pixel to pixel variations
March 2005 A. Weber
MINOS Experiment 22
FD Front End Electronics • MINOS developed an ASIC chip for PMT readout
– 32 channels
– shaping
– amplification
– sample & hold
– output driver to ADC
• Excellent product – fast shaping 500 nsec
– noise < 2 fC
– linear> 20 pC
– 6 ASICs multiplexed onto 1 ADC
March 2005 A. Weber
MINOS Experiment 23
Signal Amplification
March 2005 A. Weber
MINOS Experiment 24
Output of Pre-amplifier
March 2005 A. Weber
MINOS Experiment 25
Signal Digitisation
March 2005 A. Weber
MINOS Experiment 26
DAQ System• Trigger-less DAQ system
– ASIC close to PMT
– ADC in VME crate
– fast PVIC-bus to PC trigger farm
– search for hits correlated in space and time
1
DCPDCP
TP0
TP0TP
N
TPN TP
1
TP1
VARC0
VARC0VARC
1
VARC1VARC
2
VARC2 VARC
0
VARC0VARC
1
VARC1
ROPROP
0
VARC2
VARC2
VME
VFBVFB
2 1 0
DAQLAN
serial
Ether.ROP
ROP
15
TRCTRC
VME
VFBVFB
PVIC
DAQLAN
serial
Ether.
3
40 Mbytes/sPVIC Bus
10-100 Kbytes/s
DAQLAN
VME Readout Crates
0 Optical PVIC Bus
2.5 MB/s
To Persistent StoreTo Dispatcher
DAQLAN
TimingCentral
unitGPS
antenna
TimingPC
TimingPC
Timing System
Timestamp Clock1 sec GPS ticks
DAQLAN
3
TRCTRC
PVIC
2 1 02 1 02 1 0
BRP
BRP
BRP
BRP
PMTsHVHV HV HV
RCRC
2
TriggerProcessors
Branch Readout
Processors
Front End Electronics
• Timing System– Absolute time from GPS
(tabs= 200 nsec)
– optical distribute along large detector (trel= 4 nsec)
March 2005 A. Weber
MINOS Experiment 27
Near Detector Event
MINOS Preliminary
Etrack approx. 1.5 GeV
Low-energy track from fiducial region
March 2005 A. Weber
MINOS Experiment 28
Additional Near Detector Events
MINOS Preliminary
Etrack approx. 3.1 GeV
Medium energy track from near peak in “pseudo-medium” beam
March 2005 A. Weber
MINOS Experiment 29
Additional Near Detector Events
MINOS Preliminary
One “snarl” (beam pulse) in near detector, showing multiple events.