H A R PA Hadron Production Experiment at the

Proton Synchrotron at CERN

Motivation for the HARP experiment

The HARP Detector

MiniBooNE and HARP

HARP Motivation (general)

Measure absolute inclusive cross-sections for Hadron production with a range of targets and primary proton energies.

HARP Motivation (specific)

● Neutrino Factory Design• Atmospheric Neutrino Flux Calculations• Neutrino Fluxes for MiniBooNE and K2K• Input to Monte Carlo simulation

packages

Neutrino Factory

Æ+ , Æ-

Need to Know:

1. production rates for varying target materials, target size and proton beam energies (2-24GeV).

2. The PT distribution with high

precision to optimize muon collection.

Atmospheric Neutrinos

_

Need to Know:

1. Primary Cosmic Ray Flux*

2. Hadron Interaction Model**

* known to better than 10%

**limited data leads to ~30% uncertainty in atmospheric neutrino fluxes

MiniBooNE Flux

Æ+ŒÂ+ƒ àsource of

Œ ƒ à Ãee+ source of e background

ŒÆ0ƒ ƒ ÃeK+ e+ source of e background

ŒÆ-ƒ ƒ Ãee+K0L

source of e background

8 GeV p+

K+

Be

HARP at the CERN PS

• 200 meters in diameter• 28 GeV maximum energy• Feeds into SPS• Used to make anti-protons• Used for target expr. - HARP

HARP at the CERN PS

East Hall

T9 Secondary Beam at PS

• PS protons hit a target producing secondary particles.

• Particles are momentum selected allowing HARP to choosebeam energy (2 -15 GeV).

• However, beam consists of different particles - mainly protonsand pions.

• TOF measurements distinguish different particles in the beambefore hitting the HARP target.

NOTE: This is different from MiniBooNE. MiniBooNE gets 8 GeV protons directly from the Booster.

HARP Detector

HARP Detector

Time Projection Chamber - TPC

10-1 1 10 p(GeV/c)

Resistive Plate Chamber -RPC

HV

HV

+ + + ++

+ + + ++

+ + + ++

+ + + ++

Gas

Gas

TPC & RPC

TPC - RPC Event

HARP Detector

Drift Chambers & Spectrometer Magnet

• 0.5 T Vertical Field for momentum spectrometry• Vertical, +5°, -5° wire orientation in drift chambers• 90% Argon, 5% CO

2, 5% CH

4 gas mixture

• 150m - 700m resolution depending on incident angle• Typical single chamber efficiency of 97%

+

-

Drift Chambers & Spectrometer Magnet

HARP Detector

Threshold Cerenkov Detector• Filled with C

4F

10 (perflourobutane) at atmospheric pressure.

• Discriminates between protons and pions at high momentum.• At high beam momentum, strange particles (kaons) are also created.

C4F

10 properties:

n = 1.001415pion threshold = 2.6 GeV/ckaon threshold = 9.3 GeV/c

proton threshold = 17.6 GeV/c

HARP Detector

TOF Wall, Electron Identifier,Cosmic Trigger Wall,Beam Muon Identifier

TOF Wall - plane of scintillator counters to discriminate between protons and pions at low momentum

t ~ 210 ps)

Electron Identifier - lead-scintillating fiber counters to discriminate between hadrons on the one hand, and photons and electrons on the other.

Cosmic Trigger Wall - plane of scintillator sheets to trigger on cosmic muons for monitoring and calibration.

Beam muon Identifier - iron-scintillator calorimeter to identify beam muons.

Pion Production and pi/pPID

PT vs. P

L Box Plot for pion Production (@15GeV)

TPCTPC

TOFTOF

CerenkovCerenkov

HARP Targets

Beryllium Carbon Aluminum Copper Tin Titanium Lead

}

} Hydrogen Deuterium Nitrogen Oxygen

solid targets 2%, 5%, 50%, 100% neutrino factory, MiniBooNE, K2K

cryogenic targetsatmospheric neutrino flux

MiniBooNE and HARP

Production Rates

Decay Now Goal

Æ+ŒÂ+ƒ ÃÂ

ŒÆ0ƒ ƒ ÃeK+ e+

ŒÆ-ƒ ƒ Ãee+K0L

~50% 5%

~50% 5%

~100% 10%

~100% 10%

e+

Â+Œ ƒ à Ãe

MiniBooNE & HARP

• 1.3M events recorded in 2001 for 8 GeV protons on a 2% Be target• In August, 2002, data will be taken for a 5% and a 50% Be target

71.12 cm = 1.72

2% 5% 50%

MiniBooNE Target

HARP 2002 Data Taking

• Scheduled for 140 days of running in 2002➢28 days for cryogenic targets➢14 days for special targets➢7 days for setup and calibration➢91 days to run all targets and beam energies

• Cross-section measurements at the 1-2% level shouldbe achievable.