near detector report

Near Detector ReportNear Detector ReportNear Detector ReportNear Detector Report

International Scoping StudyUC Irvine

21 August 2006Paul Soler

University of Glasgow

International Scoping Study UC Irvine, 21 August 2006

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ContentsContents

1. MINOS near to far ratio methods2. Beam simulation near detector3. Inverse muon decay 4. Beam diagnostics5. Near Detector spectra6. Near Detector design7. R&D plans


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Four possible methods for beam flux extrapolation– NDFit method– 2D Grid method– Near to far ratio– Beam matrix method

LE-10/185kA pME/

200kApHE/200kA

Weights applied as a function of hadronic xF and pT.LE-10/

Horns off

Not used in the fit

LE-10 events

1. MINOS Near to Far Ratio Methods1. MINOS Near to Far Ratio MethodsPrediction far detector spectrum from near detector (MINOS methods, Weber)Prediction far detector spectrum from near detector (MINOS methods, Weber)

NDFit: Reweighting hadronic distributions


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2D Grid method

– Bin data in reconstructed Eν & y

– Fit weight as a function of true Eν & y

Near to far ratio– Look at differences between data and MC in Near

Detector as a function of reconstructed Energy

– Apply correction factor to each bin of re-constructed energy to Far Detector MC: c = ndata / nMC

Beam matrix– It uses the measured Near Detector distribution and

extrapolates it using a BEAM Matrix to the Far Detector.

1. MINOS Near to Far Ratio Methods1. MINOS Near to Far Ratio Methods


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Predictions for far detector do not

give perfect agreement but well

controlled.

Four methods agree very well– Different systematics

Predicted FD true spectrum from the Matrix Method

Predicted spectrum

Nominal MC

0.931020 POT

1. MINOS Near to Far Ratio Methods1. MINOS Near to Far Ratio Methods


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Flux determination with near detector (Karadzhov, Tsenov)

2. Beam Simulation Near Detector2. Beam Simulation Near Detector

Muon beam parameters :

1. polarization : 1, -1 and 0.

2. beam energies : 20, 30, 40 GeV.

3. energy distribution : Gaussian (σ = 80 MeV)

4. angular distribution : Gaussian (σ = 0.5x10-3)

5. Distribution in a plane perpendicular to the beam : Gaussian (σ = 5cm)


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Muon decay matrix element

For νμ

For anti νe

where x = 2Eν/mµ , Pµ is the polarization of the muon and θ is the angle between polarization vector and neutrino direction.

Distributions of points where νμ and anti νe cross a plane situated at 500 m from the end of the straight section and perpendicular to the beam axis for polarization 1 and -1 .

2. Beam Simulation Near Detector2. Beam Simulation Near Detector

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21cos23 xxθP+x~dxdΩ

Ndμ

ν

22

1cos1 xxθP+x~dxdΩ

Ndμ

ν


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2. Beam Simulation Near Detector2. Beam Simulation Near Detector Number of neutrinos per cm2 in the same plane for 100000 muon decays simulated Muon

energy 40 GeV.


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energy 40 GeV.


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energy 40 GeV.


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3. Inverse muon decay3. Inverse muon decay Inverse muon decay: scattering off electrons in the near detector

(Karadzhov, Tsenov) μ+νe+ν μe

Cross sections (in C.M. system):

μ+e+ e

s

ms

π

G=σ μF

222

2

222 3/12

s

)EE+E(Ems

π

G=σ ν2ν1μeμF

cosθ

m+s

ms+cosθ

m+s

ms+

s

EEms

π

G=

dcosθ

dσ2μ

μ

2e

eμeμF

22

2

222

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3. Inverse muon decay3. Inverse muon decay Energy spectra for νμ (green) and anti νe (blue). Muon energy 40 GeV.

Cylinder radius 1 m, thickness 30 cm

500 m distance

Threshold


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3. Inverse muon decay3. Inverse muon decay Energy spectra for νμ (green) and anti νe (blue). Muon energy 40 GeV.


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3. Inverse muon decay3. Inverse muon decay Polar angle for νμ (green) and anti νe (blue).

μ+e+ e

Muon energy 20 GeV.


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400m long straight section is used for these simulations.

E = 40GeV , P = 1 6.87x105 5.81x105 1.92x109

E = 40GeV , P = -1 1.67x106 6.97x104 2.81x109

E = 30GeV , P = 1 2.02x105 1.97x105 1.32x109

E = 30GeV , P = -1 5.89x105 1.60x104 1.91x109

E = 20GeV , P = 1 1.83x104 1.14x104 8.07x108

E = 20GeV , P = -1 7.83x104 7.76x102 1.14x109

3. Inverse muon decay3. Inverse muon decay Total number of muons per year (1021 muon decays per year) produced in a cylindrical detector with radius 1 m, thickness 30 cm and density 1.032

g/cm3(scintillator, total mass ~1 ton),

μ+νe+ν μe μ+e+ e

Muon energy 20 GeV.

N


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4. Beam Diagnostics4. Beam Diagnostics Beam Current Transformer (BCT) to be included at entrance of

straight section: large diameter, with accuracy ~10-3.

Beam Cherenkov for divergence measurement? Could affect quality of beam.

storage ring

shielding

the leptonic detector

the charm and DIS detector

Polarimeter

Cherenkov

BCT


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4. Beam Diagnostics4. Beam Diagnostics Muon polarization:

Build prototype of polarimeter

Fourier transform of muon energy spectrum

amplitude=> polarization

frequency => energy

decay => energy spread.


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5. Near Detector Beam Spectra5. Near Detector Beam Spectra

Near detector(s) are some distance (d~30-1000 m)

from the end of straight section of the muon storage ring. Muons decay at different points of straight section: near detector is

sampling a different distribution of neutrinos to what is being seen by the far detector

storage ring

shielding

the leptonic detector

the charm and DIS detector

Polarimeter

Cherenkov d

Different far detector baselines:0 730 km, 20 m detector: ~30 rad0 2500 km, 20 m detector: ~8 rad0 7500 km: 20 m detector: ~3 rad

If decay straight is L=100m and

d =30 m, at 8 rad, lateral

displacement of neutrinos is

0.25-1.0mm to subtend same angle.


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5. Near Detector Beam Spectra5. Near Detector Beam Spectrad=30 m, r=0.5 m

Fluxd=130 m, r=0.5 m d=1km, r=0.5 m

e

Anti

17.8 GeV

15.3 GeV

21.6 GeV34.1 GeV

29.2 GeV18.5GeV

Neutrino point source (muon decay length not taken into account)


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5. Near Detector Event Spectra5. Near Detector Event Spectrad=30 m, r=0.5 m

Event ratesd=130 m, r=0.5 m d=1km, r=0.5 m

Anti

e

25.5 GeV

22.3 GeV

26.6 GeV 37.1 GeV

32.5 GeV

23.2 GeV


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5. Near Detector Event Spectra5. Near Detector Event SpectraCompared to far detector: d=2500 km, r=20 m

e

Anti

35.8 GeV38.1 GeV

Flux

Near Detector at 1 km has similar spectra to Far Detector

Event rates

30.0 GeV 33.3 GeV


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6. Near Detector Design6. Near Detector Design Overall design of a near detector

0 Vertex detector: Choice of Pixels; eg. Hybrid pixels, Monolithic Active Pixels (MAPS), DEPFET; or silicon strips.

0 Tracker: scintillating fibres, gaseous trackers (TPC, Drift chambers, …)0 PID: 0 Calorimeter0 Muon ID

Old UA1/NOMAD/T2K magnet offers a large magnetised volume with a well known dipole field up to 0.7 T.

Use NOMAD/T2K as basis for design


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6. Near Detector Design6. Near Detector Design

Muon chambers

EM calorimeter

HadronicCalorimeter

Possible design near detector around UA1/NOMAD/T2K magnet


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6. Near Detector Design6. Near Detector Design Vertex detector

0 Identification of charm by impact parameter signature0 Demonstration of charm measurement with silicon detector: NOMAD-STAR

Impact parameter resolution

Pull:~1.02

x~33 m


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6. Near Detector Design6. Near Detector Design

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 with 2D space points (ie. Pixels) and more measurement planes

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) and 15 layers of B4C, 5 mm thick (~0.4 X0)

Fully pixelated detector with pixel size: 50 m x 400 m 200 M pixels Double sided silicon strips, long ladders: 50 cm x 50 m 360 k pixels


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7. Near Detector R&D Plans7. Near Detector R&D Plans

What needs to be measured:

1) Number of muons in ring (BCT)

2) Muon beam polarisation (polarimeter)

3) Muon beam angle and angular divergence (Cherenkov, other?)

4) Neutrino flux and energy spectrum (Near Detector)

5) Neutrino cross-sections (Near Detector)

6) Backgrounds to oscillations signal (charm background, pion backgrounds, ….), dependent on far detector technology and energy.

(Near Detector)

7) Other near detector physics: PDF, electroweak measurements, ….

ee


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7. Near Detector R&D Plans7. Near Detector R&D Plans R&D programme1) Vertex detector options: hybrid pixels, monolithic pixels (ie. CCD, Monolithic

Active Pixels MAPS or DEPFET) or strips. Synergy with other fields such as Linear Collider Flavour Identification (LCFI) collaboration.

2) Tracking: gas TPC (is it fast enough?), scintillation tracker (same composition as far detector), drift chambers?, cathode strips?, liquid argon (if far detector is LAr), …

3) Particle identification: dE/dx, Cherenkov devices such as Babar DIRC?, Transition Radiation Tracker?

4) Calorimetry: lead glass, CsI crystals?, sampling calorimeter?

5) Magnet: UA1/NOMAD/T2K magnet?, dipole or other geometry?

Collaboration with theorists to determine physics measurements to be carried out in near detector and to minimise systematic errors in cross-sections, etc.


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7. Near Detector R&D Plans7. Near Detector R&D Plans Request plan :

40k/yr

40k/yr80k/yr

80k/yr

120k/yr

120k/yr


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ConclusionsConclusions There is important synergy between existing (or planned) experiments

such as MINOS and T2K and the technology for future near detectors. Cross-sections and fluxes remain an issue. Learning the techniques that these experiments are adopting helps to formalise the problem that we will face at a neutrino factory.

A near detector at a neutrino factory needs to measure flux and cross-sections with unprecedented accuracy. Beam diagnostic devices need to be prototyped

It is worth noting that the beams measured by a near detector if it is close to straight sections (<100m) are quite different from far detector. However, at 1 km, beams start to look very similar.

We should start having some idea of what a near detector should look like. One proposal is to use the old UA1 magnet (like in NOMAD and T2K) once more.

The near detector should have a vertex detector, tracking planes, particle identification, calorimetry and muon identification. The dipole filed between 0.4-0.7 T can provide good muon momentum resolution.

R&D plans are not very well defined at the moment

near detector report

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