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Preliminary Ideas for a Near Detector Preliminary Ideas for a Near Detector at a Neutrino Factoryat a Neutrino Factory
Preliminary Ideas for a Near Detector Preliminary Ideas for a Near Detector at a Neutrino Factoryat a Neutrino Factory
Neutrino Factory Scoping Study Meeting
23 September 2005Paul Soler
University of Glasgow/RAL
Neutrino Factory Scoping Study Meeting CERN 22-23 September
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ContentsContents
1. Near Detector Aims2. Flux normalization3. Cross-sections4. Parton Distribution Functions5. Charm production6. Sin2w
7. Possible near detector technologies7.1 Silicon tracking detector7.2 Liquid argon TPC or other technologies
8. Conclusions
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1. Near detector aims1. Near detector aims Long baseline neutrino oscillation systematics:
– Flux control and measurement for the long baseline search.– Neutrino beam angle and divergence– Beam energy and spread– Control of muon polarization
Near detector neutrino physics:– Cross-section measurements: DIS, QES, RES scattering– sin2W - sin2W ~ 0.0001– Parton Distribution Functions, nuclear shadowing S from xF3 - S~0.003– Charm production: |Vcd| and |Vcs|, D0/ D0 mixing– Polarised structure functions– polarization– Beyond SM searches
General Purpose Detector(s)!!
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2. Flux normalisation (cont.)2. Flux normalisation (cont.)
e
e
e
e
Neutrino beams from decay of muons:
Spectra at Production (e.g. 50 GeV) Number CC interactions
Polarisation dependence
P=+1: gone!
Need to measure polarization!!
Neutrino Factory Scoping Study Meeting CERN 22-23 September
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2. Flux normalisation (cont.)2. Flux normalisation (cont.)
Rates:— E = 50 GeV
— L = 100 m, d = 30 m— Muon decays per year: 1020
— Divergence = 0.1 m/E
— Radius R=50 cm
100 m
E.g. at 25 GeV, number neutrino
interactions per year is:
20 x 106 in 100 g per cm2 area.
Yearly event rates
High granularity in inner region
that subtends to far detector.
Neutrino Factory Scoping Study Meeting CERN 22-23 September
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2. Flux normalisation (cont.)2. Flux normalisation (cont.) Neutrino flux normalisation by measuring: Signal: low angle forward going muon with no recoil Calculable with high precision in SM
Same type of detector needed for elastic scattering on electrons:
ee
)(2)( 2
22
22
LABinEmG
mq
msG
dy
edeF
W
WFCC
2412
104.02
)( cmGeV
EEmGe eF
CC
ee ee
)()(
ee )()(
)1(22 ymE ee
E.g. CHARM II obtained value of sin2W from this
Neutrino Factory Scoping Study Meeting CERN 22-23 September
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3. Cross sections3. Cross sections
Measure of cross sections in DIS, QE and RES. Coherent Different nuclear targets: H2, D2
Nuclear effects, nuclear shadowing, reinteractions
With modest size targets can obtain very large statistics
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4. Parton Distribution Functions(s)4. Parton Distribution Functions(s) Unpolarised and Polarised
Structure functions S from xF3 - S~0.003 Sum rules: e.g. Gross-Llewelyn
Smith polarization: spin transfer from
quarks to — NOMAD best data— Neutrino factory 100 times
more data
Neutrino Factory Scoping Study Meeting CERN 22-23 September
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mixing: doubly Cabbibo suppressedSM very small, new physics
Babar: Rmix<4x10-3 (90% CL) hep-ex/0408066
5. Charm Production5. Charm Production Charm production: Measure of Vcd and strange quark content nucleon 6-7% of cross-section at 20 GeV3% CC events:
about 3x107 charm states per year
...,,,, 00 csDDDD
McFarland
00 DD
Tagged sample
Neutrino Factory Scoping Study Meeting CERN 22-23 September
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6. sin6. sin22 ww
Elastic scattering off electrons:
Deep inelastic scattering: NC/CC Good statistical accuracy on sin2W (~0.5x10-4) but hadron uncertainties dominate
sin2W ~ 0.0001
ee ee ,
)(
,
)(
2231241106.1)( cmgg
GeV
Ee RLCC
36.0)()(
)()(
eCCCC
eNCNCR
Neutrino Factory Scoping Study Meeting CERN 22-23 September
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High granularity in inner region that subtends to far detector. Very good spatial resolution: charm detection Low Z, large Xo Electron ID Does the detector have to be of same/similar technology as far detector?
7. Near detector technologies7. Near detector technologies
Does not need to be very big (eg. R~50-100 cm)
Possibilities:— silicon or fibre tracker in a
magnet with calorimetry, electron and muon ID (eg. NOMAD-STAR??)
— Liquid argon calorimeter
Neutrino Factory Scoping Study Meeting CERN 22-23 September
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7.1 Vertex detector with spectrometer 7.1 Vertex detector with spectrometer R&D in NOMAD for short baseline detector based on silicon:
NOMAD-STAR
Does not need to be very big (eg. R~50-100 cm)
Neutrino Factory Scoping Study Meeting CERN 22-23 September
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7.1 Vertex detector with spectrometer 7.1 Vertex detector with spectrometer Longest silicon microstrip
detector ladders ever built: 72cm, 12 detectors, 50 m pitch, S/N=16:1
Vertex resolution 19 m
Neutrino Factory Scoping Study Meeting CERN 22-23 September
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7.1 Vertex detector with spectrometer 7.1 Vertex detector with spectrometer
CC event
Primary vertex
Secondary vertex
Neutrino Factory Scoping Study Meeting CERN 22-23 September
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7.1 Vertex detector with spectrometer 7.1 Vertex detector with spectrometer Vertex resolution: 19 m Impact parameter resolution: 33 m
Used NOMAD-STAR to search for charm events: marginal statistical accuracy, but was a good proof of principle
Neutrino Factory Scoping Study Meeting CERN 22-23 September
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7.1 Vertex detector with spectrometer 7.1 Vertex detector with spectrometer Efficiency very low: 3.5% for D0, D+ and 12.7% for Ds
+ detection because fiducial volume very small (72cmx36cmx15cm), only 5 layers and only one projection.
From 200 million events, about 600,000 charm events, but efficiencies can be improved.
Neutrino Factory Scoping Study Meeting CERN 22-23 September
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7.2 Other technologies 7.2 Other technologies Liquid argon TPC in a magnetic field would be able to perform as a near
detector as well
Other possible technologies that have been used or are being proposed to be used as near detectors: scintillating fibre tracker, standard gas TPC with target (T2K near detector) …
2.5 GeV e, 1.5T
Maybe the UA1/NOMAD magnet will live on again as a near detector for a neutrino factory?
Neutrino Factory Scoping Study Meeting CERN 22-23 September
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ConclusionsConclusions
The Near Detector(s) needs to meet two physics goals:– Flux control and measurement for the long baseline– A dedicated near detector neutrino physics programme
Silicon detectors could provide a solution for the near detector technology.
Other options include liquid argon TPC, SciFi tracker, or gas TPC associated with a target.