harp- hadron production experiment at cern -...

HARP- hadron production experiment at CERN

HARP- hadron production experiment at CERN

Università degli Studi e Sezione INFN, Bari, ItalyRutherford Appleton Laboratory, Chilton, Didcot, UKInstitut für Physik, Universität Dortmund, GermanyJoint Institute for Nuclear Research, JINR Dubna, RussiaUniversità degli Studi e Sezione INFN, Ferrara, ItalyCERN, Geneva, SwitzerlandSection de Physique, Université de Genève, SwitzerlandLaboratori Nazionali di Legnaro dell' INFN, Legnaro, ItalyInstitut de Physique Nucléaire, UCL, Louvain-la-Neuve, BelgiumUniversità degli Studi e Sezione INFN, Milano, ItalyP.N. Lebedev Institute of Physics (FIAN), Russian Academy of Sciences, Moscow, RussiaInstitute for Nuclear Research, Moscow, RussiaUniversità "Federico II" e Sezione INFN, Napoli, ItalyNuclear and Astrophysics Laboratory, University of Oxford, UKUniversità degli Studi e Sezione INFN, Padova, ItalyLPNHE, Université de Paris VI et VII, Paris, FranceInstitute for High Energy Physics, Protvino, RussiaUniversità "La Sapienza" e Sezione INFN Roma I, Roma, ItalyUniversità degli Studi e Sezione INFN Roma III, Roma, ItalyDept. of Physics, University of Sheffield, UKFaculty of Physics, St Kliment Ohridski University, Sofia, BulgariaInstitute for Nuclear Research and Nuclear Energy, Academy of Sciences, Sofia, BulgariaUniversità di Trieste e Sezione INFN, Trieste, ItalyUniv. de Valencia, Spain

Vladimir Ivanchenkofor the HARP Collaboration

V.Ivanchenko SLAC Geant4 Workshop, Feb 2002 2

Outline

• HARP goals and design• Geant4 at HARP• CERN T9 beam line• HARP background study• Experiment 2001• Plan 2002• Conclusions


HARP goals

• Cross sections in the energy range (2-15) GeV• The data for the neutrino factory source optimization• The data for calculation of meson flax from atmospheric

neutrino • The data for K2K and MiniBooNE experiments • The data for Geant4 hadronic models


Detector layout

drift chambers

cherenkov

TOF wall electronidentifier

spectrometermagnet

TPC/RPC solenoidmagnet

forward triggerforward RPC

muonidentifier

“characterized” beam

Neutrino Factory: ~2-24 GeVAtmospheric meson flux: 2-100 GeV

PS East Area beams: 2-15 GeV

Large Acceptance and Particle ID


The HARP Experiment

Software

Online

Offline

Large AngleDetectors

TPC

Barrel R

PC

ForwardSpectrometer

Forward R

PC

Drift C

hambers

Cherenkov

TO

F W

all

EM

Wall

Beam Instrumentationand Trigger

Beam

Cherenkovs

Beam

TO

Fs

Trackers MW

PC

Inner Trigger

Forw

ard Trigger

Muon C

atcher

Large Parallel Effortin Design and Construction


HARP at T9

HARP at T9


Nov-99 Feb-00 May-00 Aug-00 Nov-00 Feb-01 May-01 Aug-01 Nov-01

...Go!

Commissioning

Physics

Construction

TPC

CHE

RPC

Beam and Trigger

Forward Spectrometer

Software


Beam Particle identificationExample: combination of all beam detectors for beam particle identificationat 3 GeV/c.

Expected peak positions allow to calibrate and cross-check the beam-linemomentum.

Unique tags (<1% contamination):

3 GeV/c: e (BCA,BCB), π, K, p (TOF)

5 GeV/c: e (BCA), π (BCB,TOF), p (TOF)

12 GeV/c: π, p (BCA,BCB)

d

pKπ

e


⊗ 12 GeV/c p

Large Angle detectors

RPC


Forward Spectrometer: Drift Chambers

A simple beam pion

TOF WallCherenkov

Nomad Drift Chamber Module(4x3 planes)



DipoleSpectrometer

Beam Cherenkov


Cherenkov performancesData based on beam particles identified through Beam Cherenkovs , beam TOF and muon identifier.

Preliminary, photomultipliers equalizationin progress.

Not usedππ12 GeV

p rej.e, πe5 GeV

p rej.ee3 GeV

Beam TOF B-A

Beam Ckov B

Beam Ckov Aπ def.

---97.5 ± 10. %Eff muons

Eff pions >97% @ 95% C.L.(40/40)>93% @95% C.L. 113/11389. ± 10. %

12 GeV5 GeV3 GeV

---


TOF WALL

7.4m

2.5m

Continuous Laser ,Cosmic rays and pulsecalibration usedfor time-walk corrections and stability monitors.

Example: time separationand resolution for 3 GeV/cbeam particles.

pions

protons


EM identifierElectromagnetic Lead-SpaghettiCalorimeter (10X0):

Measured resolution

)(%20 GeVEEE

≈∆

Final equalization and calibration(upstream materials) in progress

DATA

G4 MC

DATA

G4 MC


SoftwareIterative Architectural Object-Oriented Design has defineddomains, dependences and interfaces;

Detailed Software Design (C++) coded and implemented;

Procedures (unit/system tests, releases) defined and implemented

Now:

• Large effort in alignment/calibration algorithms.• Reconstruction algorithms and quality checking.


DetResponseDetResponse

HarpUIHarpUI

ObjyHarpObjyHarp

ReconstructionReconstruction

ObjectCnvObjectCnv

ROOT ROOT GEANT4GEANT4

DetRepDetRep

GaudiFramework

GaudiFramework

HarpEventHarpEventHarpDDHarpDD

CLHEP+ STL

CLHEP+ STL

DAQDAQ

SimulationSimulation

DATEDATEHEPODBMSObjectivity

HEPODBMSObjectivity

EventSelectorEvent

SelectorObjy

PersistencyObjy

Persistency

SoftwareArchitecture


Geometry description

• ASCII files with a few tags:• Logical volume• Boolean operation• Positioning• Replica• Positioning of parametrised volumes• Rotations • Materials• Mixtures


HARP Geant4 simulation

• G4 for HARP is working in Gaudi Framework (LHCb)• G4 UI interface is provided by Gaudi UI• Any combination of subdetectors and sensitive detectors

can define for a given run

• User have several choices for• Event generator• Hadronic physics• Electromagnetic physics• TPC and Dipole magnetic field parametrisations• Hadronic generator for the target


HARP Geant4 simulation

• Simulation of sensitive detectors in DetResponse• Hits are stored in Gaudi Event Store• Digitisation is separated from hit production• Digi are stored in Gaudi Event Store in the format of Rec

hits and can processed as experimental data• Two types of persistency exist: ASCII files (mainly used

now for G4) and ObjectivityDB (in a progress for G4)


HARP event generators

• Standard generator “HARPgun”• G4GeneralParticleSource • ASCII input, filled from experimental events• T9 beam line simulation – 72 meters of PS

beam transport from the target to T9 hall have been performed. The mail goal: to control beam parameters.


Beam PerformancesMomentum definition: ∆/P < 1%Beam spot on target: typically, RRMS≤ 5 mm

Difficulties with thin targets (low energy):

Strong divergence after the target: hitsin forward triggers → excess of empty events

Strong divergence before the target: scrapingof solenoid magnet and target holders, overlays in the TPC (30 µs drift-time)

Difficulty at high energy (above 12 GeV/c):Intensity control on positive beam

General: Lower trigger purity than expected,Important contamination by “beam particles”generating a forward trigger (5X data-volume)under investigation.


G4 HARP background study

• All attempts to reduce background impirically fail • In order to understand the background special

Geant4 study were performed • Beam parameters were extracted from the data

using MWPC and beam counters• For beam particles multiple scattering was

disabled in the aria of MWPC for beam• Simulation were done with and without target


Results of G4 background study

• Main sources of background are following:• multiple scattering on beam counters and TPC walls (29 %)• Bremsstrahlung of beam electrons/positrons on beam counters

and TPC walls with further conversion on other walls (33 %)• δ-electron production on beam counters and TPC walls (26 %)• δ-electrons production in air (12 %)

• Simple shielding is not effective!• As a result the program to optimize HARP trigger

for 2002 run have been formulated


Results of G4 background study

DataNo target1.24.93all

MC5% Cu target8.612.115p



MCNo target0.74.93p

MCNo target0.54.73e+

ConditionItc (%)Ftp (%)p(GeV/c)Particles


Hadron production

• The special process is designed. It is active only in the target and only for primary track

• Interaction point is forced to be uniformly distribute along the target

• One of the following secondary generators can be used:• Elastic• Exclusive• Parametrised (GHEISHA)• Chiral invariant phase space (CHIPS)• String fragmetation + CHIPS• Precompound


Benchmark for G4 hadron physics

• A benchmark is designed to study G4 hadronic generators• The goals:

– Analysis strategy– Acceptance calculation– Studying Geant4

• Gaudi framework is used• No secondary interactions• One can study:

• Multiplicity of final states• Inclusive spectra• Invariant masses• Energy/momentum balance


Preliminary results of G4 hadronic generators study

π+ π- inclusive spectra


>77.8 millions physics-triggersconcentrated on thin targets and positive beam momenta:

5 target elements (out of 7+4)4 beam momenta (out of 6)

partial thick target data (K2K)

In addition, ~5M calibration events.

2001 Data 2001 plan


2002 Strategy

Winter shutdown: Data analysis to improve understanding ofdetector and beam related issues.

Then, program focus on:

• Cryogenic targets (N2,O2,D2 ,H2)

• “Final” K2K and MiniBooNE targets statistics

• Complement current targets and beam momenta with both polarities.


Conclusions• HARP: ultimate hadroproduction experiment in the regime of parents with P<15 GeV/c.

• In 20 months, the HARP detector has been builtand has collected > 78 millions physics triggers.

• The HARP collaboration will exploit the winter stop in order to analyze the available data-sample and reach the best knowledge of our beam and detector setup.

• The HARP experiment is ready to complete the aimed program 2002 by exploiting the cryogenic targetsand remaining settings.


Conclusions

• GEANT4 is one of the basic packages used by HARP

• The power and flexibility of GEANT4 toolkit is demonstrated and is utilized

• The results of HARP will be used in GEANT4• First HARP physics results are planned to be

available in March 2002

harp- hadron production experiment at cern -...

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