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!!

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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.

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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

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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

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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

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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

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7.1 Vertex detector with spectrometer 7.1 Vertex detector with spectrometer

CC event

Primary vertex

Secondary vertex

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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

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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.

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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?

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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.