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Mariyan BogomilovMariyan BogomilovCERN, CERN,
(Switzerland)(Switzerland)
University of Sofia and INRNE,University of Sofia and INRNE,(Bulgaria)(Bulgaria)
GAS@BS, Kiten, Bulgaria , Kiten, Bulgaria
THE HARP EXPERIMENTTHE HARP EXPERIMENT
On behalf of the HARP Collaboration
13-20 June 2005 13-20 June 2005
2
Motivation for Motivation for HAHAddRRon on PProduction roduction experimentexperiment
Pion/kaon yield for the design of the proton driver and target systems of neutrino factories neutrino factories
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Maximizing +(-) production yield as a function ofTarget materialProton energy GeometryCollection efficiency
Poor experimental knowledge:Few material testedLarge errors (small acceptance)
Different simulations show large discrepancies for production distribution, both in shape and normalization.
factory designfactory design
need to measure yield and +/- ratio better than 5% need differential distributions (PL,PT)
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Motivation for Motivation for HAHAddRRon on PProduction roduction experimentexperiment
Pion/kaon yield for the design of the proton driver and target systems of neutrino factories neutrino factories
Input for prediction of neutrino fluxes for the MiniBooNEMiniBooNE and K2KK2K experiments
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Analysis for K2K: motivationsAnalysis for K2K: motivations
MC only
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K2K interestsK2K interests
pions producing neutrinos pions producing neutrinos in the oscillation peakin the oscillation peak
GeVE 75.05.0
mrad
GeVP
250
1
K2KK2K
interestinterest
K2K
far
/nea
r ra
tio
K2K
far
/nea
r ra
tio
Beam MC Beam MC,confirmed by Pion Monitor
To be measured To be measured by HARPby HARP
0.5 1.0 1.5 2.0 2.50 E(GeV)
oscillationoscillationpeakpeak
One of the largest K2K One of the largest K2K systematic errorssystematic errors
on the neutrino on the neutrino oscillation parametersoscillation parameters
comes from comes from
the uncertainty on the the uncertainty on the far/near ratiofar/near ratio
beam 250km
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Motivation for Motivation for HAHAddRRon on PProduction roduction experimentexperiment
Pion/kaon yield for the design of the proton driver and target systems of neutrino factories neutrino factories
Input for prediction of neutrino fluxes for the MiniBooNE and K2K experiments
Input for precise calculation of the atmospheric neutrino flux (from yields of secondary p,K)
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Atmospheric Atmospheric flux flux
Primary flux is now considered to be known better than 10%
Most of uncertainty comes from the lack of data to construct and calibrate a reliable hadron interaction model
Model-dependent extrapolations from the limited set of data lead to about 30% uncertainty in atmospheric fluxes
Need measurements on cryogenic targets (N2, 02) covering the full kinetic range in a single experiment
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Motivation for Motivation for HAHAddRRon on PProduction roduction experimentexperiment
Pion/kaon yield for the design of the proton driver and target systems of neutrino factoriesneutrino factories
Input for prediction of neutrino fluxes for the MiniBooNE and K2K experiments
Input for precise calculation of the atmospheric neutrino flux (from yields of secondary , K)
Input for Monte Carlo generators (GEANT4, e.g. for LHC or space applications)
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HARP physics goalsHARP physics goals
Precise (~2-3% error) measurement of differential cross-section for secondary hadrons by incident p and ± with:
Beam momentum from 1.5 to 15 GeV/c
Large range of target materials, from Hydrogen to Lead
Thin and thick targets, solid, liquid and cryogenic
K2K and MiniBooNE replica targets
► Acceptance over the full solid angle► Final state particle identifications
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The HARP The HARP CollaborationCollaboration
124 physicists24 institutes
Bari University , CERN , Dubna JINR , Dortmund University , Ferrara University , Geneve University , P.N. Lebedev Physical Institute , Legnaro /INFN , Louvain-la-Neuve UCL , Milano University/INFN , Moscow INR , Napoli University/INFN , Oxford University , Padova University/INFN , Protvino IHEP, Protvino , Paris VI-VII University , RAL ,Roma I University/INFN Roma Tre University/INFN , Sheffield University , Sofia Academy of Sciences , Sofia University , Trieste University/INFN , Valencia University
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Data taking summaryData taking summary
SOLID:
CRYOGENIC: EXP:
HARP took data at the CERN PS T9 beam-line for 2 years Total: 420 M events, ~300 settings
ElementThickness,
Beam momentum
K2K: Al MiniBoone: Be LSND: H2O
5% 50%
100% Replica
5% 50%
100% Replica
10% 100%
+12.9 GeV/c +8.9 GeV/c +1.5 GeV/c
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Detector layoutDetector layout
Large Anglespectrometer
Forward spectrometer
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Beam detectorsBeam detectorsTOF-A
CKOV-A CKOV-B
TOF-B
21.4 m
T9 beam
MWPCs
Two beam Cherenkov: /K above 12 GeV
~100% e- tagging efficiency
MWPC: incident beam direction with σ<100μm, =96%
Beam TOF:/K/p at low energy
T0 with σ~70ps
Proton selection purity > 98.7%
12.9 GeV/c
K
pd
Corrected TOF (ps)
3 GeV
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Large angle spectrometer: TPCLarge angle spectrometer: TPC
dE/d
xP (GeV/c)
p
PT/P
T
PT (GeV/c)
pt = abs(1 +2) pt √2(tot)
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Large angle spectrometer: RPCLarge angle spectrometer: RPC
•Two groups: barrel and forward plane
•46 chambers;
•2 layers;
•368 pads
•Intrinsic barrel time resolution: ~220 ps
•Combined resolution
(RPC+TPC+BEAM) ~ 330 ps
Bet
a=v/
c
P (GeV/c)
p
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Forward acceptanceForward acceptance
A particle is accepted if it reaches the second module of the drift chambers
mradsx ]200 ,200[P > 1 GeV
K2K interestK2K interest
dipole magnetNDC1 NDC2
B
x
z
NDC5
beam
target
Top view
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22 NDC3
NDC4
Plane segment
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Forward trackingForward tracking
dipole magnetNDC1 NDC2
B
x
z
NDC5
beam
target
Top view
11
22 NDC3
NDC4
Plane segment
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3 track types depending upstream information1. Track-Track2. Track-Plane segment3. Track-Target/vertex
recover efficiency and avoid dependencies on track density in 1st NDC module (model dependence)Calculate efficiency separating downstream system first:
vertexdowntrack
DownstreamUpstream
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Tracking efficiencyTracking efficiency
)5().2()5()2( down
P, GeV/c x, rad y, rad
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Tracking efficiencyTracking efficiency
P, GeV/c x, rad y, rad
vertexdowntrack
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Reconstruction efficiencyReconstruction efficiency
P, GeV/c x, rad y, rad
toftrackrecon
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e++
p
number of photoelectrons
inefficiency
e+h+
TOF CHERENKOVCALORIMETER
3 GeV/c beam particles3 GeV/c beam particles
+
p
0 1 2 3 4 5 6 7 8 9 10
p
P (GeV)P (GeV)
e
k
TOFCHERENKOV
TOF CHERENKOV
CHERENKOV
CALORIMETER
TOF
CHERENKOV
CAL
Forward spectrometer: PIDForward spectrometer: PID
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Analysis for K2KAnalysis for K2KIn K2K: In K2K: EE : 0 ~ 5 GeV : 0 ~ 5 GeV
P < 10 GeV/c
< 300 mrad
Most important regionMost important region
oscillation max: oscillation max:
EE ~ 0.6 GeV ~ 0.6 GeV
1 GeV/c < P1 GeV/c < P < 2 GeV/c < 2 GeV/c
< 250 mrad< 250 mrad
E P
P vs
Study interactions of 12.9 GeV Study interactions of 12.9 GeV protons on Al with the HARP protons on Al with the HARP Forward SpectrometerForward Spectrometer
Oscillation maxOscillation max
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Combined PID probabilityCombined PID probabilityBayes theorem:
TOF cherenkov
By MC:
electrons have a peak in low energy;
the particle is rejected if p<2.6 GeV/c and Nphe >15;
where j = p,
By data:
Kaons are estimated
And subtracted
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where:
M – unfolding momentum matrix - between true and measured momentum
J – Jacobian of transformation between measured and ‘true’
- inverse tracking efficiency
- inverse geometrical acceptance
Raw yield for K2K thin targetRaw yield for K2K thin target
twaw
K2K replica targetK2K replica target
5% 5% Al target Al target 200% Al target
26
Then:
Corrections for absorption (not reaching downstream detector) ~ 10-20%
Correction for secondary interactions( in the target and not coming from vertex) ~5%
Empty target subtraction
Subtraction of electrons and kaons
PID criteria by
where ij is the fraction of observed j to be true i
True pion and proton yieldsTrue pion and proton yields
27
Cross-section calculationCross-section calculationPion cross-section Pion yield
A - atomic number
N0 - Avogadro number
- density
Z – target thickness
Npot – number of protons on target
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7 mln. triggers
3.054 mln. incoming protons
170 000 secondary tracks
+ cross-section (graphics)+ cross-section (graphics)
+ data
… Stanford-Wang fit
PRELIMINARY
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+ cross-section (table)+ cross-section (table)
PRELIMINARY
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ConclusionsConclusionsThe HARP Experiment has collected data for hadron production measurements with a wide range of beam energies and targets
Detector, PID, tracking efficiency well understood and robust
First cross-section data are available: thin (5%) K2K target, using forward region of the detector
In the near future HARP will provide many In the near future HARP will provide many important results, not only for important results, not only for physics physics!!
31
MiniBooNE beam phase spaceMiniBooNE beam phase space
Momentum and Angular distribution of pions decaying to a neutrino that passes through the MB detector.
Acceptance of HARP forward detector
8.9 GeV beam interactions on MiniBooNE replica Be target
cooling fins
32
yield for the MiniBooNE yield for the MiniBooNE thin targetthin target
Iterative PID algorithm on Be 5% target data to extract raw pion yields.
PRELIMINARY