Status of the HARP Experiment

June 2001 HARP Status – Chris Booth 1

Status of the HARP Experiment

Chris Booth

University of Sheffield


Outline

• Motivation– Neutrino Physics– Muon storage ring design

• Requirements and Design– Acceptance– Particle identification

• History and Status – Results from the technical run– Current status


Motivation – Neutrino Physics!

Conventional accelerator beamsp N + X

+

e+ e

K+ X + e+ e

Neutrino physics – first indication of physics beyond S.M.

• Solar neutrinos

• Atmospheric neutrinos

• Neutrino beams (LSND, ….)

Mixture of species

,

, e

Range of momenta of

progenitors

Uncertain fluxes


Motivation – reduced systematics

Aims of HARP

• Optimal design of target and collector for source

• Calculation of atmospheric fluxes

• Calibration of beams for K2K and MiniBooNe

• Stopped source for solid state physics

E.g. Atmospheric neutrinos:30% uncertainty in fluxes 7% uncertainty in ratio / e

Dedicated neutrino beams, from monoenergetic muons.


Targetry for Neutrino Factory• Proposal to build a muon storage ring for a -factory.

– (also first stage of a high energy -collider)

• High -fluxes are required for precision measurements– ~1012 m–2yr–1 for 732 km baseline or ~1010 m–2yr–1 for 7332 km– Requires ~1021 muons per year– Requires ~1021 pions per year– This assumes capturing ~0.6 pions/incident proton

• Need high Z target

+/– ratio should be ~1 requires low A

• Several proton driver designs • CERN: Linac+accumulator p=2 GeV/c• FNAL: Synchrotron p=16 GeV/c• CERN-BNL:Synchrotron p=24 GeV/c


HARP: hadronic d/dPT/dPL at various beam energy and targets


Targets and pion capture

Two parameters are important:• pTmax determined by inner radius

of the capture solenoid• Acceptance of the RF-system

given by pL spectrum of pions

To optimise the target and capture system requires good knowledge of the pT and pL spectra to very low pT values.


Low Energy pion production

Observe pions and protons


Surely it has all been done before !

Lack of data!!

• few old experiments: Allaby et al.(1970) Eichten et al.(1972) 24 GeV p Be

• small acceptances

• in many cases only Be target with beam energies in the range 12-24 GeV

Xlab =p/pbeam


Data required for a -Factory

We can optimize the neutrino factory design by:

1. maximizing the + – production rate /proton /GeV

2. knowing with high precision (<5%) the PT

distribution

BUT the current simulation packages (FLUKA and MARS) show a 30%-100% discrepancies on pion yields


Università degli Studi e Sezione INFN, Bari, ItalyInstitut für Physik, Universität Dortmund, Germany

Joint Institute for Nuclear Research, JINR Dubna, RussiaUniversità degli Studi e Sezione INFN, Ferrara, Italy

CERN, Geneva, Switzerland Section de Physique, Université de Genève, SwitzerlandLaboratori Nazionali di Legnaro dell' INFN, Legnaro, Italy

Institut de Physique Nucléaire, UCL, Louvain-la-Neuve, BelgiumUniversità degli Studi e Sezione INFN, Milano, Italy

Institute for Nuclear Research, Moscow, RussiaUniversità "Federico II" e Sezione INFN, Napoli, Italy

Nuclear and Astrophysics Laboratory, University of Oxford, UKUniversità degli Studi e Sezione INFN, Padova, Italy

LPNHE, Université de Paris VI et VII, Paris, FranceInstitute for High Energy Physics, Protvino, Russia

Università "La Sapienza" e Sezione INFN Roma I, Roma, ItalyUniversità degli Studi e Sezione INFN Roma III, Roma, Italy

Rutherford Appleton Laboratory, Chilton, Didcot, UK Dept. of Physics and Astronomy, University of Sheffield, UK

Faculty of Physics, St Kliment Ohridski University, Sofia, BulgariaUniversità di Trieste e Sezione INFN, Trieste, Italy

Univ. de Valencia, Spain

HARP experiment PS214

22 institutes

107 authors


• Hadronic production cross sections (d/dPT,dPL)

at various energies and with various targets• Goal: 2% accuracy over all phase space

O(106) events/setting, low systematic error

CERN PS, T9 beam, 2 GeV/c – 15 GeV/c

Approval: December 1999• "Stage 0"

Technical run with partial set-up, 25 September – 25 October 2000

• Stage 1Measurements with solid and cryogenic targets, 2001 + early 2002

• Future plans:Measurements with incoming Deuterium and Helium, 2002~100 GeV incoming beam, using NA49 set-up

HARP will measure......


Recycling!

Very short timescale re-use existing equipment & designs

• DC & TOF wall from NOMAD

• prototype TPC from ALEPH

• dipole magnet from Orsay

• Electron-identifier from CHORUS

• …

However, in practice many changes, re-optimisations etc required, so most has had to be rebuilt!


Deliverables

Input data

for the design of the Neutrino factory/Muon collider

Input data

for the Atmospheric neutrino flux calculations

Precise predictions

of the neutrino fluxes for the K2K and MiniBooNE experiments

targets will be installed in HARP

Input data

for the hadron generators in Monte Carlo simulation packages

GEANT-4


Parameters to optimise: proton energy, target material and target geometry, D2

• Proton beam 2-24 GeV

CERN: Linac 2 GeVBNL: Synch. 24 GeVFNAL: Synch. 16 GeV

Various high-Z Targets

• Li,Be,C,Al,Cu,liq.Hg etc.

(thin and thick)+/- ratio: • D2

beambackward-going pions • stopped muon

source

We Need new DATA


Large acceptance(even backward)

p/ separation K/p separation electron/p separation

Momentum evaluation over 2 decades (100 MeV–10 GeV)

Acceptance and particle-ID


Acceptance and particle-ID

Acceptance

• Target inside TPC

• Forward spectrometer (drift chambers)

Identification

• Time of flight (RPCs & scintillators)

• dE/dx (TPC)

• Cherenkov

• e & identifiers (scintillator/absorbers)


Experimental setup

drift chambers

Cherenkov

TOF wall electronidentifier

spectrometermagnet

TPC solenoidmagnet

forward triggerforward RPC

muonidentifier

beam

…-id at large pL

Tracking, low pT spectrometer

particle-id at low pL, low pT

High pT and particle-id


Targets – U.K. responsibility

Cryogenic targetsall 6 cm long

target tubetarget holder

target Z thinl (cm)

thickl (cm)

Be 4 0.81

C 6 0.76 38.0

Al 13 0.79 39.4

Cu 29 0.30 15.0

Sn 50 0.45

Ta 73 0.22 11.1

Pb 82 0.34 17.1

H2 D2 N2 O2

K2K target ~60 cm Al

MiniBooNE target

~65 cm Be

Solid targets

Special targets

> 99.99%

pure


Experimental setup

beam

TPC field cage

TPC pad plane/readout

target

ITC innertrigger cylinder

solenoid coil

RPC barrel

2.24 m


TPC

beam

1.59 m

PAD planereadout

HV plane~ 22 kV

“cork”(HV degrading +calibration systems)

Field cages

HARP

Stesalit wall (8 mm outer, 2 mm inner)

metallisation


TPC

Gate Wiring scheme

PAD size 6.515 mm2

20 PAD rows3972 PADs in total

"CALICE" preamplifier chips on the back of the PAD plane flex connection buffer amplifier pico-coax cable (5 m) FEDC (VME card with 10-bit ADC and digital circuit for data reduction)

Wire planes:anode wires (no field wires)cathode wiresgating grid

all wiring around precisionpins on a 7 mm wide spoke-wheel gate wiring

32 cm


TPC

TPC calibration systems:•Mn source•Photo-emission from UV light (aluminised optical fibre)•Gate pulsing•Radioactive gas•Cosmics

Gas choice: 90% Ar, 10% CO2

Gas speed: 5 cm/sTotal drift time: 32 s 320 time samples at 10 MHzExpect around 1% of the 1.3106 PAD-time words to contain a hit data reduction in the FEDC up to ~50 kBytes per event to be read out for up to 1000 events/spill


TPCThe TPC design takes into account the results of many detailedsimulations/calculations on: gas choice, B-field dependence, ion movements, gating studies, simulation of PAD response function, electrostatics for wire planes and field cage, mechanical deformations

Charge sharingWith field wires

Charge sharingWithout field wires


TPCTPCino prototypemini-TPC with 24 PADs•final wire configuration•90% Ar, 10% CO2•Short drift ~5 cm•"Calice" preamps•Buffer amplifiers•Pico-coax cable•Alice FE Digital Card•DATE DAQ•Monitoring•Laser for photo emission

Allows to test• PAD signals under various conditions• Gating system• Calibration systems• PAD response function• dE/dx resolution

TPCino Pad Response Functionmeasured with (point-like) -sourceand oscilloscope readout

TPCino Pad Response Functionmeasured with (point-like) -sourceand oscilloscope readout


TPC

HARP-TPCinoFull electronic chain Point-like photo emission source

preliminary:

pulseheight 10-14%

HARP-TPCinoFull electronic chain Point-like photo emission source

preliminary:

pulseheight 10-14%


TPC

TPCino test setup, full readout chain, online monitoring

FWHM of signal duration

200 nsscope view

of a single PAD10 MHz readout

30 s


RPCAdditional detector (not in the proposal)Particle (e – ) separation at low momenta (150 MeV – 250 MeV)<200 ps time resolution needed

can be achieved with RPC4 gaps of 0.3 mm thickness

module size: 192 cm 10.6 cm PAD size: 10.4 cm 2.95 cm

•Barrel-part, around the TPC: 30 RPC modules•Forward part, at the TPC exit: 16 RPC modules

Each PAD is read out by its own (OPA687) preamplifier8 PADs are added together after the amplifier stageSignal split into: trigger, TDC, ADCTotal 368 readout channels


RPC

Prototype results (T10 test beam)

= 104 ps

Time (TDC channel 50 ps)(30 ps trigger resolution still folded in)


Solenoid magnet

Gap radius 45 cm

Gap length 224 cm

Number of coils 88

Field strength 0.7 T

DC current 910 A

Power consumption

0.72 MW

Ex-ALEPH TPC90 magnetMagnet Requirements:• Homogeneous field in TPC (1.6 m long)• Br/Bz < 1%• Field strength 0.7 T• Downstream return yoke removed

Needed 50 cm extra length20 new coils of which 14 with a larger radius

new coils


Spectrometer magnet

Gap height 88 cm

Gap width 241 cm

Gap depth 171 cm

Field strength (vertical)

0.5 T

BdL 0.68 Tm

Current 2910 A

Power consumption 0.36 W

August 2000

August 2000

BdL 0.68 Tm

1 m


Spectrometer magnet

By (in y,z plane)

By (in x,z plane)

interpolation ofmagnetic field measurements


Drift chambers

23 chambers installed in HARP(69 planes)

Drift Chambers

32 mm drift length1 chamber = 1 triplet1 module = 4 chambers

wires at –5º, 0º, +5ºtotal 126 wires/chamber

8 mm gas gapgas:

90% Ar, 9% CO2, 1%

CH4

Read out by:CAEN TDC V767


Cherenkov

beam

5.4 m

2 rows of 19 PM's (8")in magnetic shieldingadditional focusing: Winston cones

Cherenkov box, 30

m3

filled with C4F10 gas

cylindrical mirror, 8

m2

curvature radius 2.4 m

2.6 GeV/c

K 9.3 GeV/c

p 17.6 GeV/c

threshold


C4F10 threshold mode

34 Chooz PMs EMI 9356KA

Optimisation of granularity for expected occupancy

PM shielding requirements

Mirrors/focussing design scheme (and technology)

Serious construction problems!

Cherenkov Design

Serious leaks! Removed from area and dismantled, to be re-welded.


Cherenkov

Mirror reflectivityMirror reflectivity

90%

700 nm300 nm

mirrorsupport

mirrorsupport

PM + shielding

PM + shielding

Winstoncone

Winstoncone


Time-Of-Flight wall39 counters2.5 cm thick

BC408

~7.4 m

2.5 m

technical runprototype results:time difference between 2 counters

280 ps

420 ps

300 ps

200 ps


Electron and Muon identifier

electron identifier

muon identifier

6.72 m

3.3 m

Electron identifier:Pb/fibre: 4/162 EM modules, 4 cm thick80 HAD1 modules, 8 cm thick

Muon identifier:Iron + scintillator slabs

Thickness 6.44 I


Trigger: internal (sci-fibs) AND external RPCs AND TOF

Outer Trigger 24 RPCs

(TOF to support the TPC e/h separation)

Inner Fibre Trigger(Backward/Large angle)

Forward RPCs

…and far TOF plane (10 m distance) for small angle particles!

Trigger system


Trigger counters

TDStarget defining scintillatordisc, 2 cm , 5 mm thick,air light guides4 photomultipliers>99.5 % efficiency per PM

TDStarget defining scintillatordisc, 2 cm , 5 mm thick,air light guides4 photomultipliers>99.5 % efficiency per PM

ITCinner trigger cylinder surrounding the target130 cm long, 7 cm 4 layers of 1 mm scint. fibreviewed by 16 photomultipliers

ITCinner trigger cylinder surrounding the target130 cm long, 7 cm 4 layers of 1 mm scint. fibreviewed by 16 photomultipliers

beam trigger

interactiontrigger


Trigger counters

2 planes of 7 scintillation countersread out from both sides

Total coverage 1.4 1.4 m2 at the solenoid exit

Forward trigger hodoscope(interaction trigger, together with RPCs)

6 cm hole for the outgoing beam

13/9/2000


Total Acceptance:

15 GeV on Be

TPC Forward Spectrometer

A 4 experiment!!


p/ separation

TPCTPC

TOFTOF

CherenkovCherenkov

p/ separation at 4 level, “conservative” simplification

PT-PL box-plot of distribution from 15 GeV p on Be thin target


pions and protons; 2 GeV p on Be

pions protons


HARP technical run


Secondary beam line

Horizontal and Vertical Beam diameter (2+2) for the extended T9 beam(simulated, without multiple scattering)

Beam particle identification:2 Cherenkov counters2 TOF counters (dist. 24 m)ČČ B

TOF

ATOF

HARPtarget


Beam optimization

Measured beam sizes ( in mm) 1.28 m in front of HARP focus

Multiple scattering effects at low momentum

= 10 mm


Beam particle identification

raw dataTOFA - TOFBversusCherenkov-2

Tim

e d

iffere

nce (

ns)

C2 (ADC counts)

1.4 ns nominal

(p – +) time difference

A complete set of Cherenkov thresholdvalues for all momenta was produced

(Calculated + Measured)

A complete set of Cherenkov thresholdvalues for all momenta was produced

(Calculated + Measured)


Beam chambers

Argon ~65%CO2 ~35%Argon ~65%CO2 ~35%

4 MWPC with 1 mm (2 mm) wire spacingtotal ~800 readout channels

Aim: • tracking of incoming beam particles (~105/spill)• monitor beam halo and muon background

analog chamber signals(20 mV, 50 ns)

New! 50% Ar, 50% C02, trace H2O

Lower threshold electronics>99.5% efficiency at lower voltage.


Drift chambers

Beam profile, xhits of 1 plane

Beam profile, xhits of 1 plane

19 cm

~680 ns

Drift time

VD 47

m/ns

Drift time

VD 47

m/ns

Efficiency versus

Vanode

94%

-spectrometer on-spectrometer off


Electron and Muon Identifier

Raw data results from the technical run(single PM’s)

Muon identifierElectron identifier

ADC countsADC counts


HARP installation status

Secondary beam line Finished, tuned.

Beam particle identification Finished, calibrated.

Incoming beam tracking Ready; Halo monitor readout to debug.

Trigger Complete; incorporating RPC.

Solid targets Mech. support and first targets finishedCryogenic targets for summer 2001.

TPC solenoid & spectrometer magnets

Finished.

TPC Under test in area. Flexi cables to repair on 4 sectors.

RPCs Installed on “dummy TPC”.

Drift chambers 68 of 69 planes working. Efficiency 90-95%.

Gas Cherenkov Under repair.

TOF wall Installed, tested, operational.

Electron & muon identifiers Installed, tested, operational.

Mid-June 2001


Remaining problemsCherenkov Counter

• Main frame delivered out-of-spec. Machined & corrected . • Serious leaks. Re-weld box (25th June - 5th July).• Test & purge (5 days); fill (5 days) ready 15th July.

TPC• Break-down field cage redesign . Warped pad boards fixed .• Assembly complete; minor leaks to fix.• Flexi micro-cables to repair on 4 sectors.• Fill & test with 2 working sectors in parallel (15 days).• Remove TPC, install final sectors, reinstall (5 days) ready 10th July.

Drift Chambers• Efficiency with non-flammable gas only 90–95%.• Revise reconstruction software to use individual hits rather than

triplets. (Various algorithms under consideration.)


Software Process

• Stringent time schedule required adoption of software engineering standards.

• Software deliverables:– Project and Configuration Management Plans– User and Software Requirements Documents– Architectural Design Document & Design Diagrams– Test Plan and Release Procedures– Traceability matrixes across software deliverables

• Domains identification & dependency structure lead to:– definition of releasable units (libraries and source code),– definition of working groups (and schedules),– definition of ordering for unit & system testing and for release.


Software Functionality

• DAQ and detectors readout (DATE).

• Storage and retrieval of physics data and settings (Objectivity DB,

AMS-HPSS interface).

• Framework including application manager, interfaces & data

exchange for the components, and event model (GAUDI).

• Physics Simulation & Detector Model (GEANT4).

• Physics Reconstruction (of individual detectors).

• Online Monitoring & Offline Calibration of detectors.

• User Interface and Event Display (ROOT).

• Foundation libs & Utilities (STL, CLHEP).


Software architecture

Reconstruction Simulation ObjyPersistency

EventDisplay DetRep ObjectCnvObjyHarpEvent

HbookCnv HarpDD HarpEvent

Framework DAQ

ROOT(external lib)

GEANT4(external lib)

CLHEP Utilities STL DATE(external lib)

Objectivity(external lib)

HBOOK(external lib)


DAQDATE systemAdditions to DATE (ALICE DAQ prototype) framework:• modifications to the event distribution algorithms in the

Event Builder• changes in the organization of data per spill (Physics

trigger, SOB, EOB, SOR, EOR)

Interfaces• PCI-VME (latency problem with start of memory transfer)• Alternative solutions are studied

New VME hardware• TDC V767, TDC V775, QDC 792


Example of data analysisData processed through the complete software chain

TOFB – TOFA time read by 35 ps resolution TDCRaw data

p+

+

=225 ps

+

p+

=200 ps

Geom. corr.

p+

+

=135 ps

+ ADC corrected

1.4 ns


Simulation


Simulation


Simulation


Event display


Reconstruction

reconstructed drift chamber triplets (MC data)


ConclusionThe HARP experiment has made considerable progress, but taking the full set of measurements will be a real challenge! We still have problems to overcome.

Technical run 25/9/2000 – 25/10/2000 achievements:• Beam line ready, including beam particle identification.• Experimental area infrastructure.• Both magnets (spectrometer, solenoid) installed and working.• Many detectors installed and functioning.• All essential software functionality (DAQ, storage, framework, simulation, reconstruction, monitoring, calibration, event display, library utilities).

Current status of additional detectors:• TOF wall Installed and operational.• RPC Installed on dummy TPC.• Electron identifier Installed and working.• Cherenkov Re-welding to fix leaks. Ready 15th July.• TPC Repairing micro-cable connections. Ready ~10th July.• Cryogenic targets July – August.


The HARP detector: Large Acceptance, PID Capabilities ,

Redundancy

TPC, momentum and PID (dE/dX)

at large PT

TPC, momentum and PID (dE/dX)

at large PT

Drift Chambers:Tracking and low

PT spectrometer

Drift Chambers:Tracking and low

PT spectrometer

1.5 T dipole spectrometer1.5 T dipole spectrometer

Threshold gas Cherenkov: identification

at large PL

Threshold gas Cherenkov: identification

at large PL

0.7 T solenoidal coil0.7 T solenoidal coil

Target-TriggerTarget-Trigger

EM filter (beammuon ID andnormalisation)

EM filter (beammuon ID andnormalisation)

Drift Chambers:Tracking

Drift Chambers:Tracking

TOF: identification

in the low PL

and low PT region

TOF: identification

in the low PL

and low PT region


Aim: hadronic d/dPT/dPL - various beams and targetsAim: hadronic d/dPT/dPL - various beams and targets

High statistics O(106)/ “setting” & low systematic errors

Goal: 2% accuracy over all phase space

Stage I: proton/ beam in the range 2-15 GeV/c, multiple solid + cryo. targetsStage II: Additional (cryogenic) targets and additional Deuterium/Helium beamStage III: 15-100 GeV/c beams (SPS)

What HARP can do in Summary:


Many thanks to.....

LHC/ACR LHC/ECR (cryogenic targets)

LHCb (GAUDI)

TIS division (safety issues)

ALICE (DATE system)

NA49 (TPCino test setup)

EP/ESS group (electronic pool)

EP/ACD group (ITC construction)

DELPHI (BC preamps)

ALICE, NA49, ALEPH, DELPHI (TPC advice)

EST division (alignment, cable mounting, gas supply, gas system, CERN workshops)

EP/DED group (gas system)

EP/ES group (electronics mounting and design)

EP/ED group (TPC and RPC electronics)

IT division (computing support, network)

PS division (beam, experimental area infrastructure )

EP/EC group (magnets, field measurements and RPC)

NA52 (TOF counters)ST division (transport, cooling, electricity, safety infrastr.)

TA1 group (technical support, design, mirrors)

SPL division (orders and CERN stores)

GEANT4 collaboration

Technical staff of home laboratories