BEACH04 Chicago, June 28-July 3 200 4 A.Tonazzo - HARP pion yields for neut rino beams /1 Hadron Production Cross- Hadron Production Cross- Sections and Secondary Sections and Secondary Particle Yields from 2 to 15 Particle Yields from 2 to 15 GeV using Neutrino Beam GeV using Neutrino Beam Targets Targets • The HARP Experiment – Physics goals and motivations – Summary of the experimental program – Detector overview and performance • The fist physics analysis: pion yields from K2K target – Goals – Results Alessandra Tonazzo, Università Roma Tre and INFN On behalf of the HARP Collaboration
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The HARP Experiment Physics goals and motivations Summary of the experimental program
Hadron Production Cross-Sections and Secondary Particle Yields from 2 to 15 GeV using Neutrino Beam Targets. The HARP Experiment Physics goals and motivations Summary of the experimental program Detector overview and performance The fist physics analysis: pion yields from K2K target Goals - PowerPoint PPT Presentation
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BEACH04 Chicago, June 28-July 3 2004 A.Tonazzo - HARP pion yields for neutrino beams /1
Hadron Production Cross-Sections and Hadron Production Cross-Sections and Secondary Particle Yields from 2 to 15 Secondary Particle Yields from 2 to 15
GeV using Neutrino Beam Targets GeV using Neutrino Beam Targets
• The HARP Experiment– Physics goals and motivations
– Summary of the experimental program
– Detector overview and performance
• The fist physics analysis: pion yields from K2K target – Goals
– Results
Alessandra Tonazzo, Università Roma Tre and INFN
On behalf of the HARP Collaboration
BEACH04 Chicago, June 28-July 3 2004 A.Tonazzo - HARP pion yields for neutrino beams /2
HARP physics goalsHARP physics goals
Precise (~2-3% error) measurement of
d2/dpTdpL
for secondary HAdRon Production by incident p and ± with– Beam momentum from 1.5 to 15 GeV/c– Large range of target materials, from
Hydrogen to Lead
►Acceptance over the full solid angle►Final state particle identification
BEACH04 Chicago, June 28-July 3 2004 A.Tonazzo - HARP pion yields for neutrino beams /3
Input for prediction of neutrino fluxes for the MiniBooNE and K2K experiments
Pion/Kaon yield for the design of the proton driver and target system of Neutrino Factories and SPL- based Super-Beams
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)
HARP Physics MotivationsHARP Physics Motivations
BEACH04 Chicago, June 28-July 3 2004 A.Tonazzo - HARP pion yields for neutrino beams /4
Data taking summaryData taking summary
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
SOLID:
CRYOGENIC: EXP:
HARP took data at the CERN PS T9 beamline in 2001-2002 Total: 420 M events, ~300 settings
BEACH04 Chicago, June 28-July 3 2004 A.Tonazzo - HARP pion yields for neutrino beams /5
The HARP ExperimentThe HARP Experiment
124 physicists 24 institutes
BEACH04 Chicago, June 28-July 3 2004 A.Tonazzo - HARP pion yields for neutrino beams /6
The HARP ExperimentThe HARP Experiment
BEACH04 Chicago, June 28-July 3 2004 A.Tonazzo - HARP pion yields for neutrino beams /7
The HARP detector layoutThe HARP detector layout
TRACKING + PARTICLE ID at Large angle and Forward
BEACH04 Chicago, June 28-July 3 2004 A.Tonazzo - HARP pion yields for neutrino beams /8
Beam detectorsBeam detectors
• Beam tracking with MWPCs :– 96% tracking efficiency
using 3 planes out of 4– Resolution <100m
MiniBoone target
TOF-A
CKOV-A CKOV-B
TOF-B
21.4 m
T9 beam
MWPCs
BEACH04 Chicago, June 28-July 3 2004 A.Tonazzo - HARP pion yields for neutrino beams /9
Beam particle selectionBeam particle selection
• Beam TOF:– separate /K/p at low
energy over 21m flight distance
– time resolution 170 ps after TDC and ADC equalization
– proton selection purity >98.7%
• Beam Cherenkov:– Identify electrons at low energy, at
high energy, K above 12 GeV– ~100% eff. in e- tagging
3 GeV/c beam
K
12.9 GeV/c beam
K
p
d
BEACH04 Chicago, June 28-July 3 2004 A.Tonazzo - HARP pion yields for neutrino beams /10
Status of TPCStatus of TPC
pT/pT
pdE/dx
Elastic scattering of 3 GeV p and on H2 target
Missing mass mx
2 = ( pbeam + ptarget – pTPC )
Red: using dE/dx for
PID
pppp
pp
BEACH04 Chicago, June 28-July 3 2004 A.Tonazzo - HARP pion yields for neutrino beams /11
Analysis for K2K: motivationsAnalysis for K2K: motivations
• Computation of fluxes at SK is based on near/far ratio R– For pointlike source (no
oscillations), R~1/r2 – If the near detector does not
see a pointlike source, R depends on E
• Current K2K computation of R is based on MC– Confirmed by production
measurement (pion monitor) at E>1 GeV
– Extrapolated to E<1 GeV : the interesting region for oscillations !
beam 250km
BEACH04 Chicago, June 28-July 3 2004 A.Tonazzo - HARP pion yields for neutrino beams /12
Analysis for K2K: motivationsAnalysis for K2K: motivations
BEACH04 Chicago, June 28-July 3 2004 A.Tonazzo - HARP pion yields for neutrino beams /13
Analysis for K2K: interesting regionAnalysis for K2K: interesting region
K2K needs measurement of pions with E>1 GeV E<4.5 GeV <300 mrad
►Forward region • Main tracking detectors:
drift chambers• PID detectors: TOF,
Cherenkov, calorimeter
Dip from neutrino oscillations in K2K
they come from decay of these pions:
BEACH04 Chicago, June 28-July 3 2004 A.Tonazzo - HARP pion yields for neutrino beams /14
P > 1 GeV
mradsx
]200 ,200[
K2Kinterest
K2K interest
Forward acceptanceForward acceptance
dipoleNDC1 NDC2
B
x
z
A particle is accepted if it reaches the second module of the drift chambers
BEACH04 Chicago, June 28-July 3 2004 A.Tonazzo - HARP pion yields for neutrino beams /15
Forward Tracking: NDCForward Tracking: NDC
• Reused NOMAD Drift Chambers
• 12 planes per chamber, wires at 0°,±5° w.r.t. vertical
• Hit efficiency ~80% (limited by
non-flammable gas mixture)– stable in time– lowered by high particle flux– recovered between spills– correctly reproduced in the
simulation
Alignment with cosmics and beam muons
drift distance resolution ~340 m
Plane efficiencies
Side modules
BEACH04 Chicago, June 28-July 3 2004 A.Tonazzo - HARP pion yields for neutrino beams /16
Forward trackingForward tracking
dipole magnetNDC1 NDC2
B
x
z
NDC5
beam
target
Top view
11
22 NDC3
NDC4
Plane segment
33
• 3 track types depending on the nature of the matching object upstream the dipole1. Track-Track
2. Track-Plane segment
3. Track-Target/vertex
• Aim: recover as much efficiency as possible and avoid dependencies on track density in 1st NDC module (hadron model dependent)
BEACH04 Chicago, June 28-July 3 2004 A.Tonazzo - HARP pion yields for neutrino beams /17
The momentum and angular resolutions are well within the K2K requirements
MCMC
datadata
11type
No vertex No vertex constraint constraint includedincluded
TOF time resolution ~160 ps =>3 separation of /p (K/)
up to 4.5 (2.4) GeV/c=>7 separation of /p at 3 GeV/c
Separate /p (K/) at low momenta• 42 slabs of fast scintillator read at both ends
by PMTs
3 GeV beam particles3 GeV beam particles
datadata
p
BEACH04 Chicago, June 28-July 3 2004 A.Tonazzo - HARP pion yields for neutrino beams /22
Forward PID: CalorimeterForward PID: Calorimeter
• Pb/fibre: 4/1– EM1: 62 modules, 4 cm thick– EM2: 80 modules, 8 cm thick
• Total 16 X0
• Reused from CHORUS
• Calibration with cosmic rays:– Measurement of attenuation
length in fibers– Module equalization
Energy resolution 23%/sqrt(E)• intrinsic resolution 15%/sqrt(E)• convoluted with beam spread at
detector entrance
electrons
pions
3 GeV3 GeV
datadata
BEACH04 Chicago, June 28-July 3 2004 A.Tonazzo - HARP pion yields for neutrino beams /23
ekpphe
phephe
pPEEpPNpPpP
pPEEpPNpPpPEENpP
,,,21
2121
)|()|,,()|,()|,(
)|()|,,()|,()|,( ),,,,|(
tof cerenkov calorimetermomentumdistribution
Using the Bayes theorem:
1.5 GeV 3 GeV 5 GeV 1.5 GeV 3 GeV 5 GeV
datadata we use the beam detectors to establish the “true” nature of the particle
Forward PID: Forward PID: efficiency and purity efficiency and purity
Iterative approach: dependence on the prior removed after few
iterations
j-(t) = Nj
-true-obs / Nj-
true j
-(t) = Nj-true-obs / Nj
-obs j-(t)/ j
-(t)
BEACH04 Chicago, June 28-July 3 2004 A.Tonazzo - HARP pion yields for neutrino beams /24
pion efficiency
3
1
)(
t
trackti
tracki
The 3 types of tracks must be treated separately because of the different momentum resolution
3
1
)()()(
)( 111
t
tj
tjt
j
tijtrack
iacci
i NM
)(
)()()(
kj
kbkgj
kjk
jN
NN
pion purity
pion yield
tracking efficiency
migration matrix(not computed yet)acceptance
depend on momentum resolution
i = bin of true (p,)
j = bin of recosntructed (p,)
The cross sectionThe cross section
BEACH04 Chicago, June 28-July 3 2004 A.Tonazzo - HARP pion yields for neutrino beams /25
• To be decoupled from absorption and reinteraction effects we have used a thin target
p-e/ misidentification background
K2K replica targetK2K replica target
5% 5% Al target Al target
200% Al target
Raw dataRaw data
p > 0.2 GeV/c|y | < 50 mrad
25 < |x| < 200 mrad
Pion yieldPion yield
BEACH04 Chicago, June 28-July 3 2004 A.Tonazzo - HARP pion yields for neutrino beams /26
5% Al targetp > 0.2 GeV/c|y | < 50 mrad
25 < |x| < 200 mrad
Pion yieldPion yield
After PID After PID correctioncorrection
After After efficiency efficiency correctioncorrection
BEACH04 Chicago, June 28-July 3 2004 A.Tonazzo - HARP pion yields for neutrino beams /27
Pion yieldPion yield
After After acceptance acceptance correctioncorrection
5% Al target p > 0.2 GeV/c|y | < 50 mrad
25 < |x| < 200 mrad
Systematics are still to be evaluated:• tracking efficiency know to 5%• expect small effect from PID
BEACH04 Chicago, June 28-July 3 2004 A.Tonazzo - HARP pion yields for neutrino beams /28
ConclusionsConclusions
• The HARP Experiment has collected data for hadron production measurements with a wide range of beam energies and targets
• Status of detector– Forward region: good tracking and PID– Large angle: much recent progress
• First physics results are available: thin (5%) K2K target– Using forward region of the detector
• To do– Compute data deconvolution and migration matrix– Evaluate systematic errors– Analyse empty target data for background subtraction– Investigate =0 region: saturation effects due to beam particle removal– Introduce normalization for absolute cross-section (using min.bias trigger)– … go on to full statistics, and to the rest of the data !
BEACH04 Chicago, June 28-July 3 2004 A.Tonazzo - HARP pion yields for neutrino beams /29
BackupBackup
BEACH04 Chicago, June 28-July 3 2004 A.Tonazzo - HARP pion yields for neutrino beams /30
• The efficiency of NDC2 and NDC5 is flat within ~5%.
• The efficiency of the lateral modules (3 and 4) is flat within 10%
• The combined efficiency is not sensitive to these variations.
NDC 2 NDC 5NDC 4NDC 3datadata
NDC module efficiencyNDC module efficiency
NDC2 NDC5
NDC3
NDC4
dipole
BEACH04 Chicago, June 28-July 3 2004 A.Tonazzo - HARP pion yields for neutrino beams /31