minos detector experience in brief

NF detector meetingIC, May 7 2005

Geoff Pearce, RAL

Minos Detector Experiencein brief

Geoff Pearce, RALNF detector technology discussions

I.C. May 7, 2005

• The Minos Context• Detector Essentials & Elements• Assembly, installation, maintenance• Event reconstruction, resolutions, profiles• Finer grained calorimeter


Geoff Pearce, RAL

Minos - context

Baseline : 730km

High intensity νμ beam from Fermilab to Soudan (Mn)

Two detectors, Near (1kT) and Far (5.4kT)

Primary measurement : Compare ν energy spectrum in the Far Detector to the un-oscillated expectation from the Beam and Near Detector

• Observe oscillation minimum

• Confirm oscillatory behaviour in νμ sector

• Measure Δm232 to ~10%

• Look for νμ → νe oscillations, measure θ13?

1kton near detector 5.4kton far detector


Geoff Pearce, RAL

Minos – Energy Regime120GeV M.I. protons, graphite target

2.5 1013 / 8.67 µs pulse, 1.9s rep. rate (.25MW)

Beam energy can be tuned by adjusting position of 2nd horn relative to target

Both νµ and νµ beams_

Nominal Beam Configurations

Energy regime ~ 1 – 25 GeV

Δm2 expectation dropped considerably since conception/design

LE beam best match for Δm2 ~ 2-3 10-3 eV2 at the Minos baseline

Lower energy than NF, but not too disimilar


Geoff Pearce, RALMINOS Far DetectorEssential features

5.4 kton magnetised tracking calorimeter, B ~1.5T

484 steel/scintillator planes built in 2 supermodules

2.54cm thick steel, 192 4x1cm scint. strips per plane

• orthogonal orientation on alternate planes – U,V

• optical fibre readout

Veto shield covers top/sides for atmospheric v

Multi-pixel (M16) PMTs read out with VA electronics

• 8-fold optical multiplexing

• chips individually digitised, sparsified & read out when dynode above a threshold

• excellent time resolution – 1.56ns timestamps

Continuous untriggered readout of whole detector

Interspersed light injection (LI) for calibration

Software triggering in DAQ PCs (independent of ND)

• highly flexible : plane, energy, LI triggers in use

• spill times sent from FNAL to FD trigger farm

GPS time-stamping to synch FD data to ND/Beam

Coil

Veto Shield

The completed Minos Far Detector


Geoff Pearce, RALDetector Elements

U V U V U V U Vsteel

scintillator

orthogonal orientations of strips

4.1cm x 1cm extruded polystyrene strips

TiO2 reflective coating

Groove for 1.2mm WLS fiber to collect light

Steel scintillator sandwich

25.4mm steel, 1cm scintillator

Alternate planes have orthogonal strip orientations (U,V)

Fibres carry light to MAPMTs

M16 (FD) M64 (ND)

Optical multiplexing in FD

• 8 fibres per pixel

Scintillator strips in light-tight modules, 8/plane

192 scintillator strips on each plane

M16


Geoff Pearce, RAL

Module Assembly & Testing

Placing Scintillator strips in light case

Design lends itself well to parallel construction

Matches many University workshop capabilities

Multiple factories for scintillator planes used by Minos

Division of labour – construction speed

Cost ~ $600 / module

Gluing WLS fibers

These can be important considerations


Geoff Pearce, RAL

FD most challenging

• Remote (Soudan, Mn)

• narrow mine shaft

• taken down in pieces and assembled underground

ND planes assembled above ground

Both detectors installed to schedule

Detector assembly and Mounting

Installation / maintenance at remote location highly successful


Geoff Pearce, RAL

MINOS Near DetectorEssential features

1 kton (total mass) magnetised tracking calorimeter

Partially instrumented

• 282 steel planes, 153 scintillator planes

• reduced sampling in rear planes (121-281) “spectrometer section” used for muon tracking

High instantaneous ν rate, ~ 20ev/spill in LE beam

No multiplexing except in spectrometer region (4x)

Fast “QIE” electronics

• continuous digitisation on all channels during spill

(19ns time-slicing). Mode enabled by spill signal.

• dynode triggered digitisation out of spill (cosmics)

GPS time-stamping / Software triggering in DAQ

• all in spill hits written out by DAQ

• standard cosmics triggers out of spill

Minos Near Detector as installation neared completion

Same basic design as Far Detector


Geoff Pearce, RALEvent Reconstruction

‘u’ - view

‘v’ - view

ghost hits due to

multiplexing

plane #

stri

p #

Strip readout provides two 2D views (U,V) – combine to get 3D hits

Resolution ~ strip width (angular resoln. on moon shadow <0.5deg)

Multiplexing at FD complicates reconstruction, but soluble.

MC event – zoomed in


Geoff Pearce, RAL

(Real) Far Detector Beam Event

νµ


Geoff Pearce, RALNear Detector Eventsspecial needs

One spill in Medium Energy Beam

Intensity = 2.5 1013 pps

Multiple events in detector

Events resolved using timing

ND readout has 19ns bucket resolution

Near Detector must be able to cope with high rate


Geoff Pearce, RALMagnetic Field

Stopping muonPrange = 3.86 GeV/c

Pcurvature = 4.03 GeV/c

B

PEs

time

VZ

UZ

1.5T magnetic field in steel generated by coil

• Momentum measurement

• Charge separation

Δpµ/pµ = 10% (curvature)

Δpµ/pµ = 6% (range – if available)

Far Detector cosmic muon (courtesy MT)

Good knowledge of field vital


Geoff Pearce, RALCalibration DetectorThe 3rd major Minos detector

• Vital to understand energy response to reconstruct Eν

Eν = pµ + Ehad

• Minos design ports very well to test beam studies

• Can study detector issues vital to physics

• Minos built a 1m x 1m x 3.7m “mini-Minos and ran in CERN test beams to

• study response to π, µ, e, p

• test MC simulation

• look at near / far detector differences

• energy scale calibration


Geoff Pearce, RAL

CalDet : sample events at 2 GeV

M. Kordosky

TOF/Cerenkov system at CalDet provides pure samples

Colour scale = MIPs

Energy distribution profile used to identify pid in Minos


Geoff Pearce, RALMinos Calibration DetectorResponse to π, p, e

MC expectation

Preliminary

Energy Resolution

CalDet analysis nearing completion. Publications in preparation


Geoff Pearce, RAL

MINOS Event Profiles

e CC Event

NC Event• often diffuse

NC Event

• can mimic , e

CC EventUZ

VZ

• +hadronic activity

• track

• compact shower

• typical EM shower profile

MCARLO

νe / NC

challenging but do-able at low energies.


Geoff Pearce, RALBuilt for NDK, ~ 1Gev

1.6mm thin steel

(Minos has 25.4mm steel)


Geoff Pearce, RAL

Soudan2 eventsHigh resolution

Bubble chamber quality

410 MeV electron shower

Gaps from γ propogation

Steel thickness can be tuned to needs -- and wallet


Geoff Pearce, RAL

Summary and Conclusions

• Modular, simple, low risk, safe, not expensive • Magnet field can be applied over whole steel volume

– Momentum measurement– charge ID– You get iron.

• Sampling frequency, steel thickness can be chosen to match physics requirements

• Active components would be chosen to optimise cost/performance– Scintillator (eg liquid, like Nova)– Photodetectors (eg MA256, HPD, etc)– Electronics, DAQ would clearly be chosen from technology of the day

• Near detector can be same technology

• Minos style detector is an option worth consideration


Geoff Pearce, RAL

Soudan events

High energy event

fast exiting muon

two interacting pions


Geoff Pearce, RAL

minos detector experience in brief

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