Near Detector at a Neutrino Factory Chuzenji Lake, Nikko, Japan. 10 November 2005 Paul Soler...

Near Detector at a Neutrino FactoryNear Detector at a Neutrino FactoryNear Detector at a Neutrino FactoryNear Detector at a Neutrino Factory

Chuzenji Lake, Nikko, Japan. 10 November 2005

Paul SolerUniversity of Glasgow/RAL

Vertex 2005, Chuzenji Lake, Nikko, Japan. 10 November 2005

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ContentsContents

1. Physics motivation Neutrino Factory1.1 Neutrino oscillations1.2 Neutrino factory1.3 Neutrino factory physics reach

2. Near Detector at a Neutrino Factory2.1 Flux normalization2.2 Cross-sections2.3 Parton Distribution Functions2.4 Charm production2.5 Sin2w

3. Near detector requirements4. NOMAD-STAR, an R&D prototype5. Near detector ideas


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1.1 Neutrino Oscillations1.1 Neutrino Oscillations Neutrino oscillations well established Neutrino flavour mixing: Pontecorvo-Maki-Nakagawa-Sakata

(PMNS) matrix

Atmospheric neutrinos: SuperKamiokande

1)2(sin45 232

23

23223 102.3 eVm

3

2

1

U

e

ijijijij sandcwhere

cs

sc

iδecs

sccs

sc

U

sin,cos

0

010

0

00

010

001

0

0

001

100

0

0

1313

1313

2323

23231212

1212


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1. Neutrino Oscillations1. Neutrino Oscillations

Solar neutrinos (SuperKamiokande, Sudbury, Chlorine and Gallium Experiments) and KamLand reactor experiment:

1.3446.0tan 1210.007.012

2

256.05.0

212 109.7 eVm

Sudbury KamLand


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1. Neutrino Oscillation fits1. Neutrino Oscillation fits

Consistent picture emerging Global fit provides 23, 12, m12

2 and m232

13 not known, mass hierarchy not known,CP violation phase not known.


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1.2 Neutrino Factory1.2 Neutrino Factory Matter-antimatter asymmetry

of the universe: baryogenesis (CP violation in quark sector), leptogenesis (CP violation in lepton sector)

e

e

e

e

Conceptual design: neutrinos produced from muon decay in storage ring. Rate calculable by kinematics of decay (Michel spectrum)

Neutrino factory: very long baseline oscillation experiments to measure 13, mass hierarchy and leptonic CP violation


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1.3 Neutrino Factory physics reach1.3 Neutrino Factory physics reach Far detector (3000-7000 km) can

search for “wrong-sign” muons in appearance mode (for example, Large Magnetic Detector)

Background: charm production, charge misidentification.

Qt = P sin2 cut eliminates backg at 10-6

Large Magnetic Detector

iron (4 cm) + scintillators (1cm)

beam20 m

20 m

B=1 T

40KT40KT

e

e

50%

50%

wrongwrongsignsignmuonmuon

e

detectordetector

not detected

De

e

De e

NC

CC

Hadron decay

Other Detectors: liquid argon TPC, water Cherenkov, emulsion can search for either e, or appearance


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1.3 Neutrino Factory physics reach1.3 Neutrino Factory physics reach Can detect sign of m2

32 due to matter effects

Determine 13 and CP phase simultaneously: need ~1021 muons/year

Optimal CP phase sensitivity ~6000 km but

can obtain >5 sensitivity for ~1000-8000 km


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2. Near detector aims2. Near detector aims To achieve physics goals of neutrino factory, need to establish near

detector for near/far ratio. 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– Measurement of charm backgrounds

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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2.1 Flux normalisation (cont.)2.1 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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2.1 Flux normalisation (cont.)2.1 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.

With 50 kg 109 interactions/yr

Yearly event rates

High granularity in inner region

that subtends to far detector.


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2.1 Flux normalisation (cont.)2.1 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 measurement as 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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2.2 Cross sections2.2 Cross sections Measure of cross sections in Deep Inelastic (DIS), Quasi-

Elastic (QE) and Resonance Production (RES). Coherent background to many interactions) Different nuclear targets: H2, D2

Nuclear effects, nuclear shadowing, reinteractions

With modest size targets

can obtain very large

statistics


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2.3 Parton Distribution Functions(s)2.3 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

2.4 Charm Production2.4 Charm Production Charm production: Measure of Vcd and strange quark content nucleon

Measure charm vs pt (background to oscillations) 6-7% of cross-section at 20 GeV3% CC events:

about 3x107 charm states per year

...,,,, 00 csDDDD

McFarland

00 DD

Clean tagged sample


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2.5 sin2.5 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


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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?

3. Near detector requirements3. Near detector requirements

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:

problems with rate

NOMAD-STAR (Silicon TARget)


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4. NOMAD-STAR4. NOMAD-STAR R&D in NOMAD for short baseline detector based on silicon:

NOMAD-STAR (NIMA 413 (1998), 17; NIMA 419 (1998), 1; NIMA 486 (2002), 639; NIMA 506 (2003), 217.)

Total mass: 45 kg of B4C target (largest density for lowest X0)


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Aim of NOMAD-STAR: reconstruct short lived particles in a neutrino beam

to determine capabilities detection: use impact parameter signature of charm decays to mimic

impact parameter ~ 62 m, normal charged current (CC) interactions ~30 m

4. NOMAD-STAR4. NOMAD-STAR


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Longest silicon microstrip detector ladders ever built: 72cm, 12 detectors, S/N=16:1

Detectors: Hamamatsu FOXFET p+ on n, 33.5x59.9 mm2, 300 m thick, 25 m pitch, 50 m readout

VA1 readout: 3 s shaping



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22

CC event

Primary vertex

Secondary vertex



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Most chips stable, but some chips showed varying level of noise

Maybe the same as charge build-up seen in Babar?



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Increase noise in some ladders affected some efficiencies: compensated by clustering algorithm with cuts as function of ladder


S/N

16

10


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Vertex resolution: y = 19 m Impact parameter resolution: 33 m

Double vertex resolution: 18 m from Ks reconstruction

Pull:~1.02

x~33 m


x~18 m z~280 m


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Charm event reconstruction:– Implementation of Kalman filter – Constrained fit method to extract charm signatures

Used NOMAD-STAR to search for charm events: marginal statistical accuracy, but was a good proof of principle



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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 109 CC events/yr, about 3.1x106 charm events, but efficiencies can be improved.



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Passive target can provide target mass, but affects vertex and tracking reconstruction efficiency due to scatters

Improve efficiency by having fully active silicon target. For example: 52 kg mass can be provided by 18 layers of Si 500 m

thick, 50 x 50 cm2 (ie. 4.5 m2 Si) Optimal design: fully pixelated detector (could benefit from Linear

Collider developments in MAPS, DEPFET or Column Parallel CCD). Could also be with 3D detectors or silicon strips.

Other technologies:– Liquid argon TPC in a magnetic field: maybe rate is a problem – Scintillating fibre tracker– Standard gas TPC with target (likeT2K near detector), …

International Scoping Study (ISS) for a neutrino factory (July 2005 to August 2006): aim to define the scope of physics parameters, neutrino factory machine technology and detector technology needed to launch a full design study 2007-2010. Near detector will be considered within detector working group.

5. Near Detector Ideas 5. Near Detector Ideas


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Vertex for CP.

Conclusion Haiku: unique form of very compact and succint

Japanese poetry that captures the essence and beauties of nature.

Haiku poems consist of 3 verses of 5 syllables, 7 syllables and 5 syllables. Maximum exponent of Haiku poetry: Basho Matsuo (17th century).

My own (humble) attempt at a Haiku poem:Leptogenesis,

Oscillations to find,

Near Detector at a Neutrino Factory Chuzenji Lake, Nikko, Japan. 10 November 2005 Paul Soler...

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