Status of the HARP Experiment

1
Status of the HARP Experiment

• Chris Booth
• University of Sheffield

2
Outline

• Motivation
• Neutrino Physics
• Muon storage ring design
• Requirements and Design
• Acceptance
• Particle identification
• History and Status
• Results from the technical run
• Current status

3
Motivation Neutrino Physics!

• Neutrino physics first indication of physics
  beyond S.M.
• Solar neutrinos
• Atmospheric neutrinos
• Neutrino beams (LSND, .)

• Conventional accelerator ? beams
• p N ? ? X
• ? ? ??
• ? e ?e
• ? K X
• ? ? e ?e

Mixture of species ??, ??, ?e Range of momenta
of progenitors Uncertain fluxes
4
Motivation reduced ? systematics

• E.g. Atmospheric neutrinos
• 30 uncertainty in fluxes
• 7 uncertainty in ratio ?? / ?e
• ? Dedicated neutrino beams, from monoenergetic
  muons.

• 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

5
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 m2yr1 for 732 km baseline or 1010
  m2yr1 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 Linacaccumulator p2 GeV/c
• FNAL Synchrotron p16 GeV/c
• CERN-BNLSynchrotron p24 GeV/c

6
HARP hadronic ds/dPT/dPL at various beam energy
and targets
7
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.

8
Low Energy pion production
Observe pions and protons
9
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
10
Data required for a ?-Factory
We can optimize the neutrino factory design by
1. maximizing the p p production rate /proton
/GeV 2. knowing with high precision (lt5) the PT
distribution BUT the current simulation packages
(FLUKA and MARS) show a 30-100 discrepancies on
pion yields
11
HARP experiment PS214

• Università degli Studi e Sezione INFN, Bari,
  Italy
• Institut für Physik, Universität Dortmund,
  Germany
• Joint Institute for Nuclear Research, JINR Dubna,
  Russia
• Università degli Studi e Sezione INFN, Ferrara,
  Italy
• CERN, Geneva, Switzerland
• Section de Physique, Université de Genève,
  Switzerland
• Laboratori Nazionali di Legnaro dell' INFN,
  Legnaro, Italy
• Institut de Physique Nucléaire, UCL,
  Louvain-la-Neuve, Belgium
• Università degli Studi e Sezione INFN, Milano,
  Italy
• Institute for Nuclear Research, Moscow, Russia
• Università "Federico II" e Sezione INFN, Napoli,
  Italy
• Nuclear and Astrophysics Laboratory, University
  of Oxford, UK
• Università degli Studi e Sezione INFN, Padova,
  Italy
• LPNHE, Université de Paris VI et VII, Paris,
  France
• Institute for High Energy Physics, Protvino,
  Russia
• Università "La Sapienza" e Sezione INFN Roma I,
  Roma, Italy
• Università degli Studi e Sezione INFN Roma III,
  Roma, Italy
• Rutherford Appleton Laboratory, Chilton, Didcot,
  UK
• Dept. of Physics and Astronomy, University of
  Sheffield, UK

22 institutes 107 authors
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HARP will measure......

• 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 1
• Measurements 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

13
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!

14
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
15
Parameters to optimise proton energy, target
material and target geometry, D2
CERN Linac 2 GeV BNL Synch. 24 GeV FNAL
Synch. 16 GeV

• Proton beam 2-24 GeV

• Li,Be,C,Al,Cu,liq.Hg etc.
• (thin and thick)

Various high-Z Targets
p/p- ratio

• D2 beam

backward-going pions

• stopped muon source

We Need new DATA
16
Acceptance and particle-ID
Momentum evaluation over 2 decades (100 MeV10
GeV)
Large acceptance (even backward)
p/p separation K/p separation electron/p
separation
17
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)

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Experimental setup
TOF wall
particle-id at low pL, low pT
electron identifier
Cherenkov
-id at large pL
muon identifier
spectrometer magnet
forward trigger forward RPC
TPC solenoid magnet
High pT and particle-id
beam
drift chambers
Tracking, low pT spectrometer
19
Targets U.K. responsibility
target Z thin l (cm) thick l (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
Solid targets
gt 99.99 pure
Cryogenic targets all 6 cm long
H2 D2 N2 O2
K2K target 60 cm Al
MiniBooNE target 65 cm Be
target tube target holder
Special targets
20
Experimental setup
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TPC
Field cages
HV plane 22 kV
cork (HV degrading calibration systems)
PAD plane readout
metallisation
Stesalit wall (8 mm outer, 2 mm inner)
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TPC
PAD size 6.5?15 mm2 20 PAD rows 3972 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)
32 cm
Wire planes anode wires (no field wires) cathode
wires gating grid all wiring around
precision pins on a 7 mm wide spoke-wheel
Gate Wiring scheme
gate wiring
23
TPC
Gas choice 90 Ar, 10 CO2 Gas speed 5
cm/?s Total drift time 32 ?s ? 320 time samples
at 10 MHz Expect around 1 of the 1.3?106
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

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

24
TPC
The TPC design takes into account the results of
many detailed simulations/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 sharing With field wires
Charge sharing Without field wires
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TPC

• TPCino prototype
• mini-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 Function measured with
(point-like) ?-source and oscilloscope readout
26
TPC
HARP-TPCino Full electronic chain Point-like
photo emission source preliminary ?pulseheight
10-14
27
TPC
TPCino test setup, full readout chain, online
monitoring
scope view of a single PAD 10 MHz readout
200 ns
30 ?s
FWHM of signal duration
28
RPC
Additional detector (not in the
proposal) Particle (e ?) separation at low
momenta (150 MeV 250 MeV) lt200 ps time
resolution needed can be achieved with RPC 4
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)
  preamplifier
• 8 PADs are added together after the amplifier
  stage
• Signal split into trigger, TDC, ADC
• Total 368 readout channels

29
RPC
Prototype results (T10 test beam)
? 104 ps
Time (TDC channel 50 ps)
(30 ps trigger resolution still folded in)
30
Solenoid magnet

• Ex-ALEPH TPC90 magnet
• Magnet Requirements
• Homogeneous field in TPC (1.6 m long)
• Br/Bz lt 1
• Field strength 0.7 T
• Downstream return yoke removed
• Needed 50 cm extra length
• 20 new coils
• of which 14 with a larger radius

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
new coils
31
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
32
Spectrometer magnet
By (in x,z plane)
interpolation of magnetic field measurements
By (in y,z plane)
33
Drift chambers
Drift Chambers 32 mm drift length 1 chamber 1
triplet 1 module 4 chambers wires at 5º, 0º,
5º total 126 wires/chamber 8 mm gas gap gas
90 Ar, 9 CO2, 1 CH4 Read out by CAEN TDC
V767
23 chambers installed in HARP (69 planes)
34
Cherenkov
threshold
? 2.6 GeV/c
K 9.3 GeV/c
p 17.6 GeV/c
cylindrical mirror, 8 m2 curvature radius 2.4 m
35
Cherenkov Design

• 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!

Serious leaks! Removed from area and dismantled,
to be re-welded.
36
Cherenkov
mirror support
Mirror reflectivity
90
700 nm
300 nm
Winston cone
PM shielding
37
Time-Of-Flight wall
39 counters 2.5 cm thick BC408
38
Electron and Muon identifier
Electron identifier Pb/fibre 4/1 62 EM modules,
4 cm thick 80 HAD1 modules, 8 cm thick Muon
identifier Iron scintillator slabs Thickness
6.44 ?I
electron identifier
3.3 m
6.72 m
muon identifier
39
Trigger system
Trigger internal (sci-fibs) AND external RPCs
AND TOF
Outer Trigger 24 RPCs (TOF to support the TPC e/h
separation)
Forward RPCs
Inner Fibre Trigger (Backward/Large angle)
and far TOF plane (10 m distance) for small
angle particles!
40
Trigger counters
TDS target defining scintillator disc, 2 cm ?, 5
mm thick, air light guides 4 photomultipliers gt99.
5 efficiency per PM
ITC inner trigger cylinder surrounding the
target 130 cm long, 7 cm ? 4 layers of 1 mm ?
scint. fibre viewed by 16 photomultipliers
beam trigger
interaction trigger
41
Trigger counters
Forward trigger hodoscope (interaction trigger,
together with RPCs)
2 planes of 7 scintillation counters read out
from both sides Total coverage 1.4 ? 1.4 m2 at
the solenoid exit
42
Total Acceptance
15 GeV ? on Be
Forward Spectrometer
TPC
A 4p experiment!!
43
p/? separation
44
pions and protons 2 GeV p on Be
pions
protons
45
HARP technical run
46
Secondary beam line
Horizontal and Vertical Beam diameter (2?2?)
for the extended T9 beam (simulated, without
multiple scattering)
Beam particle identification 2 Cherenkov
counters 2 TOF counters (dist. 24 m)
47
Beam optimization
Measured beam sizes (? in mm) 1.28 m in front of
HARP focus Multiple scattering effects at low
momentum
? 10 mm
48
Beam particle identification
raw data TOFA - TOFB versus Cherenkov-2
1.4 ns nominal (p ?) time difference
A complete set of Cherenkov threshold values for
all momenta was produced (Calculated Measured)
49
Beam chambers

• 4 MWPC with 1 mm (2 mm) wire spacing
• total 800 readout channels
• Aim
• tracking of incoming beam particles (105/spill)
• monitor beam halo and muon background

Argon 65 CO2 35
analog chamber signals (20 mV, 50 ns)
New! 50 Ar, 50 C02, trace H2O Lower threshold
electronics gt99.5 efficiency at lower voltage.
50
Drift chambers
Beam profile, x hits of 1 plane
94
19 cm
-spectrometer on -spectrometer off
Drift time ? VD ? 47 ?m/ns
680 ns
Efficiency versus Vanode
51
Electron and Muon Identifier
Raw data results from the technical run (single
PMs)
52
HARP installation status
Mid-June 2001
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 finished Cryogenic 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.
53
Remaining problems

• Cherenkov 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 9095.
• Revise reconstruction software to use individual
  hits rather than triplets. (Various algorithms
  under consideration.)

54
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.

55
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).

56
Software architecture
57
DAQ

• DATE system
• Additions 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

58
Example of data analysis
Data processed through the complete software chain
TOFB TOFA time read by 35 ps resolution TDC
59
Simulation
60
Simulation
61
Simulation
62
Event display
63
Reconstruction
64
Conclusion

• The 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.

65
The HARP detector Large Acceptance, PID
Capabilities , Redundancy
Threshold gas Cherenkov p identification at
large PL
TOF p identification in the low PL and low PT
region
Drift Chambers Tracking and low PT spectrometer
EM filter (beam muon ID and normalisation)
Target-Trigger
0.7 T solenoidal coil
Drift Chambers Tracking
TPC, momentum and PID (dE/dX) at large PT
1.5 T dipole spectrometer
66
What HARP can do in Summary
Aim hadronic ds/dPT/dPL - various beams and
targets

• High statistics O(106)/ setting low
  systematic errors

Goal 2 accuracy over all phase space
Stage I proton/p beam in the range 2-15 GeV/c,
multiple solid cryo. targets Stage II
Additional (cryogenic) targets and additional
Deuterium/Helium beam Stage III 15-100 GeV/c
beams (SPS)
67
Many thanks to.....
EP/EC group (magnets, field measurements and RPC)
PS division (beam, experimental area
infrastructure )
GEANT4 collaboration
NA49 (TPCino test setup)
EP/ES group (electronics mounting and design)
ALICE, NA49, ALEPH, DELPHI (TPC advice)
EP/ED group (TPC and RPC electronics)
IT division (computing support, network)
TA1 group (technical support, design, mirrors)
NA52 (TOF counters)
ST division (transport, cooling, electricity,
safety infrastr.)
LHCb (GAUDI)
ALICE (DATE system)
Technical staff of home laboratories
EST division (alignment, cable mounting, gas
supply, gas system, CERN workshops)
EP/ESS group (electronic pool)
SPL division (orders and CERN stores)
TIS division (safety issues)
DELPHI (BC preamps)
EP/DED group (gas system)
LHC/ACR LHC/ECR (cryogenic targets)
EP/ACD group (ITC construction)