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Defining the energy of the proton driver the role of HARP as hadro-production experiment. M. Apollonio, on behalf of the HARP Collaboration [Univ. of Trieste and INFN]. Overview. The experiment and its goals Status of Analysis Large Angle Region Small Angle (or Forward) Region

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Defining the energy of the proton driver the role of harp as hadro production experiment

Defining the energy of the proton driverthe role of HARP as hadro-production experiment

M. Apollonio, on behalf of the HARP Collaboration

[Univ. of Trieste and INFN]

CERN -Physics with a multiMW proton source- M.Apollonio


Overview
Overview

  • The experiment and its goals

  • Status of Analysis

    • Large Angle Region

    • Small Angle (or Forward) Region

  • Conclusions & Plans

CERN -Physics with a multiMW proton source- M.Apollonio


Harp ps214
HARP (PS214)

  • HAdRonProductionExperiment at PS;(from proposal(1)):

  • optimize thep+(p-) yieldfor then-factory

  • calculations ofbeam fluxesforK2KandMiniBoone

  • input for calculations ofatmospheric neutrino flux

  • input for Monte Carlohadronic generators

[(1) CERN-SPSC/99-35, SPSC/P315, Nov. 15th 1999]

CERN -Physics with a multiMW proton source- M.Apollonio


N factory but also super beams
n-factory (but also super-beams)

  • maximize p+(p-) production yield (/proton/GeV)

  • optimize:

    • targetmaterial

    • protonenergy

    • collection(pL,pT)

  • simulations showlarge discrepancies on p yieldanddistributions

  • Experimental knowledge rather poor:

    • Small acceptance, few materials tested

    • Old (Allaby et al., 1970, Eichten et al. 1972)

  • Aim:p yield (p+/p-)knownbetter than 5%

 thick target program: high Z at several p

CERN -Physics with a multiMW proton source- M.Apollonio


The k 2 k case

one of thelargest systematic

errors in K2K in then oscillation

parameterscomes from the

uncertainty on the far/near ratio:

depends on p-prod. model used

2.0

1.5

2.5

0

0.5

1.0

n

Pp

the K2K case

qp

To be measured

by HARP

Oscill. MAX

  • special program with K2K-replica Al target

  • K2K request: D(F/N)/(F/N) < 3%

En (GeV)

Beam MC confirmed by

Pion Monitor

Beam MC

CERN -Physics with a multiMW proton source- M.Apollonio


Data taking campaign 2001 2002
DATA taking campaign: 2001-2002

  • P [1.5 GeV/c – 15 GeV/c]

  • (quasi)full solid angle(1)coverage

  • widelist oftargets:materials and sizes

    • fromH to Pb

    • 2%, 5%,50%,100% l

  • High event rate: 2.5 kHz (~106 evts/day)

[(1) target inside the TPC!]

CERN -Physics with a multiMW proton source- M.Apollonio


O(106) events per setting

30 Tbytes of data

420 million

events

CERN -Physics with a multiMW proton source- M.Apollonio


T9-secondary line @ CERN-PS

Large Angle

target

Small Angle

HARP:detector overview

CERN -Physics with a multiMW proton source- M.Apollonio


Simulated p from p on Be target (2-15 GeV/c)

TPC p/p PID

2 GeV/c

15 GeV/c

Ckov p/p PID

TPC p/p PID

TOF p/p PID

TOF p/p PID

CERN -Physics with a multiMW proton source- M.Apollonio


Large angle tpc 0 7 t

  • calibration/equalisation, based on:

    • high statistics cosmics

    • 83Kr -41.6 keV-

    • 55Fe -5.9,3.0 keV- (2003 campaign)

    • data

  • these data have allowed

    • computation of gains and mapping of dead pads: likely to be done on a run by run basis

    • first evaluation of dE/dX

    • first evaluation of the performance of a correction for a cross talk effect

    • improvement in momentum resolution of 30%

    • check of the improvements: data with a cryogenic H2 target, 3 GeV/cp’s and protons are being analyzed, looking for elastic scattering: p(),p  p(),p

Large Angle:TPC (0.7 T)

  • TPC coversbasically all the(pL,pT)space at low momenta, (~2 GeV/c), and most of it even at higher momenta (~15 GeV/c)

CERN -Physics with a multiMW proton source- M.Apollonio


p

p,m

dE/dX

calibration with radioactive sources

drf=1.19 mm

cosmics data

before x-talk correction

after x-talk correction

P (GeV/c)

55Fe

83Kr

drf=1.51 mm

CERN -Physics with a multiMW proton source- M.Apollonio


Elastic scattering p p p p p p

p missing mass

p missing mass

Elastic Scattering: p(p)p  p(p)p

  • Normalization+calibration tool:

    • measure elastic cross-section

    • compare with the average cross section from literature (accuracy ~ several percents)

    • adjust momentum and covariance matrix of all tracks to get right c2 distribution for elastic events

    • tune MC to get the right elastic cross section

Pc

Pd

1Gev/c

Pa

Mx2=(pa+pb-pd)2

CERN -Physics with a multiMW proton source- M.Apollonio

3Gev/c


Small angle basically covered by the forward detectors
Small Angle: basically covered by the forward detectors

  • tracking & momentum measurement:

    • provided bydrift chambers(from NOMAD)+dipole magnet(1.0 Tm)

  • PIdgiven by an overlapped combination of:

    • a thresholdCherenkovcounter

    • atime of flight

    • anelectron calorimeter

CERN -Physics with a multiMW proton source- M.Apollonio


Forward tracking

NDC4

NDC2

NDC1

NDC5

dipole magnet

target

1

beam

B

2

NDC3

Forward Tracking

momentum resolution

MC

case 1

data

CERN -Physics with a multiMW proton source- M.Apollonio


P < 4.5GeV/c

p+

light particles

3 GeV beam particles

12.9 GeV K2K thin target

p

p

PId

  • p/p separation (as a function of P)

  • P < 4.5 GeV/c: relies on theTOF system

Target+TOF-Wall

l

ta tb tc t0

tw

  • Tof-W resolution: ~ 160 ps  >7sp/p at 3 GeV

  • Beam resolution: ~180ps (expected to improve)

CERN -Physics with a multiMW proton source- M.Apollonio


3 GeV/c5 GeV/cbeam particles

e+

Nphel

p

p

p+

p inefficiency

p inefficiency

Th(K): 9.2 GeV/c

Th(p): 2.6 GeV/c

p+

p+

e+

number of photoelectrons

P (GeV/c)

  • p/p separation

    • P > 3 GeV/c: relies on a thresholdCherenkov

  • p/K separation

    • 3<P<9 GeV/c

CERN -Physics with a multiMW proton source- M.Apollonio


h+

hadrons

12.9 GeV /c K2K thin target

3 GeV/c beam particles

small electron

contamination

e+

CERN -Physics with a multiMW proton source- M.Apollonio


Harp first analysis
HARP combination of first analysis

  • Focused on the K2K case

  • The small angle region covers the (q,p)region relevant for K2K

  • well known region of the apparatus in terms of

    • acceptance

    • PId

    • efficiency (tracking, matching, PId …)

CERN -Physics with a multiMW proton source- M.Apollonio


K 2 k case reprise
K combination of 2K case (reprise)

K2K region of

interest

  • Thin Al (5% l), Pbeam=12.9 GeV/c

  • Pp>1 GeV/c

  • |q|<250 mrad

CERN -Physics with a multiMW proton source- M.Apollonio


Cross section
Cross Section: combination of

bkg: misidentified p

(i,j)=(p,q)

normalization:not computed yet

p-yield

migration matrix:

not computed yet

Total efficiency

CERN -Physics with a multiMW proton source- M.Apollonio


P yield corrected for efficiency
p combination of yield corrected for efficiency

results presented in Moriond

  • The errors reflect the lack of MC statistics

  • Plots integrated over q and p

  • No systematic errors included

arbitrary units

arbitrary units

proton background for Tof

3 MC hadron generators

IMPORTANT

This background

can be computed

with the data

CERN -Physics with a multiMW proton source- M.Apollonio


Conclusions i
Conclusions-I combination of

  • HARP: recorded 420M events in 2 years (2001-2002)

  • The results shown today (first presented in Moriond) used 1/6 of our K2K thin target data

  • Forward spectrometer & PId detectors are well understood

  • MC/Data production “machinery” well under control

  • Data statistics is not a problem (5.6 M events after data quality)

  • Small systematic error expected

CERN -Physics with a multiMW proton source- M.Apollonio


Conclusions ii
Conclusions-II combination of

  • The forward angle analysis shows the potential of the experiment:

    • 1st cycle to be concluded very soon (full K2K replica, full statistics, systematics, normalization …)

  • The Large Angle analysis will fully exploit the physics reach of the experiment:

    • TPC calibration being refined + readiness for analysis

  • Plans: produce a preliminary result for proton driver energy at Villars workshop

CERN -Physics with a multiMW proton source- M.Apollonio


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