HARP progress SPSC October 2007 Alain Blondel
Progress report from HARP
Overview of new resultsForward analysisAccelerator Neutrino Beam ( K2K, MiniBooNE),
Extended Air Showers
Large angle analysisNeutrino Factory , A dependence etc.etc.
Comments on the RBH report
A HAdRon Production experiment at the CERN PS (PS214) Alain Blondel on behalf of the HARP collaboration
HARP progress SPSC October 2007 Alain Blondel
Università degli Studi e Sezione INFN, Bari, ItalyRutherford Appleton Laboratory, Chilton, Didcot, UK Institut für Physik, Universität Dortmund, GermanyJoint Institute for Nuclear Research, JINR Dubna, RussiaUniversità degli Studi e Sezione INFN, Ferrara, ItalyCERN, Geneva, Switzerland TU Karlsruhe, GermanySection 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, Italy LPNHE, 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
TheThe HARP HARPCollaborationCollaboration
24 institutes24 institutes~120 collaborators~120 collaborators
HARP progress SPSC October 2007 Alain Blondel
Hadron production on nuclear targetsa) complicated b) uninteresting for hadronic physics c) difficult to measure well
==> data are sparse and Monte-Carlos are very uncertain
d) important to optimize Neutrino factory and muon collider design e) absolutely mandatory for neutrino beam experimentsf) also LHC simulations and Extended Air Showes
measure!
Different generators applied to MiniBooNE beam
HARP progress SPSC October 2007 Alain Blondel
HARP approved 2000built in 17 monthsrun sept. 2001 -> nov 2002
106 triggers at each of thesesettings
Beam line PIDForward detectors (pions, Kaons) --> neutrino beams - K2K, - MiniBooNE, - atmospheric, - Low-medium energy superbeam(s)
Large Angle detectors-->neutrino factory
Targetmaterial
Target length
()
BeamMomentum
(GeV)
#events(millions
)
Solid targets
Be 2%
(2001)
5%
100%
±3± 5± 8
± 12± 15
For negative polarity, only 2% and 5%
233.16
C
Al
Cu
Sn
Ta
Pb
K2K Al 5, 50, 100, replica
+12.9 15.27
MiniBooNE Be +8.9 22.56
Cu “button”
Cu +12.9, +151.71
Cu “skew” Cu 2 +12 1.69
Cryogenictargets
N7
6 cm
±3± 5± 8
± 12± 15
58.4308
D1
H1
H2 18 cm ±3, ±8, ±14.5 13.83
WaterH20 10, 100 +1.5,
+8(10%)9.6
HARP progress SPSC October 2007 Alain Blondel
HARP BEAM COUNTERS--identify and count incoming particles (downscaled trigger)--define beam particle impact in target+ empty target runs to subtract effect of non-target material and count beam composition in electrons and muons
HARP progress SPSC October 2007 Alain Blondel
HARP publications - Detectors and performanceLaser-Based Calibration for the HARP Time of Flight SystemM. Bonesini et al, IEEE TRANS. NUCL. SCIENCE, VOL. 50, NO. 4, AUGUST 2003 1053
The time-of-flight TOFW detector of the HARP experiment: construction and performanceM. Baldo-Ceolin et al, Nucl. Instr. Meth. A 532 (2004) 548–561
Physics Performance of the Barrel RPC System of the HARP ExperimentBogomilov et al. IEEE TRANSACTIONS ON NUCLEAR SCIENCE, VOL. 54, NO. 2 (2007)
Particle identification algorithms for the HARP forward spectrometerM. G. Catanesi et al, Nucl.Instrum.Meth. A521: 899-921 (2007)
The HARP Detector at the CERN PSG. Catanesi et al Nucl. Instrum. Meth. A571: 527-561 (2007), 564-573(2007)V. Ammosov et al, Nucl. Instrum. Meth. A571: 561-564 (2007)
Momentum scale in the HARP TPC G. Catanesi et al arXiv:0709.2806v1 [physics.ins-det], submitted to JINST
The Time Response of Glass RPCs to Heavily Ionizing ParticlesA.Artmonov et al, arXiv:0709.3756 [physics.ins-det], submitted to JINST
In preparation :
On the HARP TPC Dynamic Distortion : A Bagulia et al .
HARP progress SPSC October 2007 Alain Blondel
HARP publications -- Forward analysis
Measurement of the production cross-section of positive pions in p-Al collisions at 12.9 GeV/c (K2K target measurement)
M.G. Catanesi et al, hep-ex/0510039, Nucl. Phys. B732: 1-45 (2006)
Measurement of the production cross-section of positive pions in the collision of 8.9 GeV/c protons on beryllium (MiniBooNE target measurement)
M.G. Catanesi et al, hep-ex/0702024v2 to appear in Eur. Phys. J. C
In preparation:
Charged pion production by 3 GeV/c-12 GeV/c protons on a carbon target (Atmospheric Flux)M.G. Catanesi et al, to be submitted to Astr. Part.
Measurement of the production cross-section of negative pions in the collision of 8.9 GeV/c protons on beryllium (MiniBooNE target measurement for antineutrinos)M.G. Catanesi et al, draft in preparation
HARP progress SPSC October 2007 Alain Blondel
p(GeV/c)
θ(rad) region of interest for MiniBooNE
momentum res. from data.
- empty target(beam particles)
- p vs beta(TOF)
- elastics in H2
HARP progress SPSC October 2007 Alain Blondel
K2K Flux prediction for near and far detectors and far/near ratio
note improvement over existing data
errors are smaller and safer
HARP progress SPSC October 2007 Alain Blondel
no oscillation
flux*0.6
best osc. fit
Reconstructed « single ring » Quasi-elastics in SuperKamiokande
==> spectral shape + normalizationshow oscillation (no oscillation curve for demonstration only)
K2K final results (using HARP input,4.1 -> 4.4 C.L. improved by factor 3)
K2K results (incl. HARP)M. H. Ahn et al., K2K Collaboration, Phys. Rev. D74 (2006) 072003
HARP progress SPSC October 2007 Alain Blondel
HARP Be 5% 8.9 GeV/c Results
0.75<p<5 GeV/c30<theta<210 mradCrucial for MiniBooNE which has no near detector!+ SciBooNE to measure cross-sections around 500-900 MeV neutrinos (region of interest for T2K)
HARP progress SPSC October 2007 Alain Blondel
Systematic errors here: forward 8.9 GeV/c Berylium (MiniBooNE)
improvements in-- tertiary interactions(use our own pC and C data)-- PID
Al data
HARP progress SPSC October 2007 Alain Blondel
More HARP data for accurate flux predictions coming:
K± production data
thick targets
π - production data
main source of νe flux for MiniBooNE
Direct measurement with rescattering and absorption
Anti-neutrino flux measurement
Kp
HARP progress SPSC October 2007 Alain Blondel
Atmospheric neutrino fluxes : the Harp contribution
Most of the 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 leads to about 30% uncertainty in atmospheric fluxes
cryogenic targets O2, N2
primary flux
e
e
decaychains
N2,O
2
Kp
....
hadronproducti
on
HARP progress SPSC October 2007 Alain Blondel
p+C @ 12 GeV/c
• leading particle effect
• stat.syst. errors
●
○
log scale
Draft in preparations
HARP progress SPSC October 2007 Alain Blondel
HARP publications
Large Angle analysis(Neutrino Factory measurements)
Measurement of the production of charged pions by protons on a tantalum targetM.G. Catanesi et al, Eur. Phys. J. C51 (2007) 787
Large-angle production of charged pions by 3 GeV/c–12 GeV/c protons on carbon copper and tin targetsM.G. Catanesi et al, submitted to Eur. Phys. J. C
Large-angle production of charged pions by 3 GeV/c–12 GeV/c protons on a beryllium , aluminum and lead targets:M.G. Catanesi et al, submitted to Eur. Phys. J. C
In preparation :
Large-angle production of charged pions in the HARP expriment with incident protons on nuclear target : M.G. Catanesi et al. (Draft in preparation ) FULL SPILL analysis(beams 3 GeV/c -12.9 GeV/c , Al, Be,C, Cn, Pb,Sn,Ta targets)
Large-angle production of charged pions in the HARP expriment with incident pions on nuclear target : M.G. Catanesi et al. (Draft in preparation ) FULL SPILL analysis(beams 3 GeV/c -12.9 GeV/c , Al, Be,C, Cn, Pb,Sn,Ta targets)
HARP progress SPSC October 2007 Alain Blondel
The TPC surprises -- cross-talk -- dead channels-- static distortions (E-field mismatch) --> EXB effects-- dynamic distortions (E-field build up) ibid-- B-field distortions... ...
The RPC surprise -- observed sensitivity to particle dE/dx beyond standard time-walk correction
HARP progress SPSC October 2007 Alain Blondel
“Large Angle” analysisbeam momenta: 3, 5, 8, 12 GeV/c
events: require trigger in ITC (cylinder around target)
TPC tracks:>11/20 points, momentum measured and track originating in targetPID selection of pions for 100-800 MeV/c additional selection to avoid track distortions due to ion charges in TPC:first part of spill (30-40% of data kept, correction available for future improvement)
Corrections:Efficiency, absorption, PID, momentum and angle smearing by unfolding method(same as pC data analysis in forward spectrometer)
Backgrounds:secondary interactions (simulated)low energy electrons and positrons (all from 0)predicted from + and - spectra (iterative) and normalized to identified e+-.
HARP progress SPSC October 2007 Alain Blondel
Determination of corrections
-- cross-talk, dead channels and equalization: from TPC tracks-- static corrections special study during 2003 cosmic run with dedicated'beam' scintillator finger-- dynamic correctionsobserved since first days from signed impact parameter distributionmomentum bias correlated with d0develop model model of charge build-up based on recorded events
HARP progress SPSC October 2007 Alain Blondel
Benchmarks
-- cosmics were used to optimize the momentum resolution by comparing the two halves of through-going muons -- high dE/dx region for protons (7-8 MIPS) was used as a momentum benchmark for 340 MeV/c particles
-- Main benchmark is elastic scattering data in LH2 runsallows determination of momentum scale, bias, efficiency
-- also, study of RPCs for heavily ionizing particles
HARP progress SPSC October 2007 Alain Blondel
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7
LA Spectrometer performance: benchmarks
momentum resolution
0
20
40
60
80
100
120
140
200 400 600 800 1000 1200 1400 1600dE/dx (ADC counts)
entries
0
10
20
30
40
50
60
70
0 200 400 600 800 1000 1200 1400 1600dE/dx (ADC counts)
entr
ies
-p PID with dE/dx
-e PID with dE/dx
momentum calibration:cosmic rayselastic scattering
PID:dE/dx used for analysis TOF used to determine efficiency
elastic scattering:absolute calibration of efficiencymomentumangle (two spectrometers!)
HARP progress SPSC October 2007 Alain Blondel
missing mass peak from large angle proton track(position of peak verifies momentum scale -- +15% shift is completely excluded)
The elastic scattering benchmark
efficiency
Comparison of predicted vs measured track allowsLA tracking benchmark
momentum scale
[1/p (predicted-measured)]/(1/p)
HARP progress SPSC October 2007 Alain Blondel
Stability from LH2 target to other targets
consider average momentum of protons with dE/dx [7-8] MIPs
H2 setting
2%Al13 12 8 5 3
Be12 9 8 5 3
Carbon 12 8 5 3
Copper12 8 5 3
H2
Lead12 8 5 3
Tin12 8 5 3
Ta12 8 5 3
HARP progress SPSC October 2007 Alain Blondel
RPC response to low energy protons
RPCs are calibrated with ~1 particles (pion, electrons)and time-walk correction applied
protons exhibit a shift from th. curve ??claim was made (RBH, Ammosov et al) that this reveals a momentum bias (from a sagitta error)
HARP progress SPSC October 2007 Alain Blondel
Investigation of RPC effect using elastic scattering H2
-- elastic scattering data @ 5 GeV -- use predicted momentum from elastic scattering kinematics-- calculate expected arrival in RPCs and compare with data
observation of a clear shift !
=> RPC calibrated for pions cannot be used for momentum benchmark with protons!!!
Hydrogen, 5GeV/c, from kinematics pad row 3
HARP progress SPSC October 2007 Alain Blondel
dynamic distortions
dynamic distortions had been first observed in 2003 by d0-curvature correlation
1/
Q*d0
d0
event number in spill
d0
before static corr
after static corr
HARP progress SPSC October 2007 Alain Blondel
For the analysis of the LA HARP data showed until now we used about 1/3 of the data.
This statistical sacrifice was due to the presence of dynamic distortions caused by build up of ion-charge density in the drift volume during the 400 ms beam spill, caused by a partial 'transparency' of the cathode wire grid.
A pragmatic approach was chosen: we limited our analysis to the early part of the beam spill where the effects of the dynamic distortions in the TPC are still small (more than 30% of available statistics).
This choice does not have important consequences on the final data analysis since the cross-section measurements are limited by systematical and not by statistics.
Nevertheless the use of the full statistics allows more refined analyses.
We have developed a full spill TPC calibration, derived from first principles, based on the influence that positive ions have on the drift
The results for all the beam energies and all thin targets are now available. The preparation of the corresponding papers is in progress
LA Analysis improvements
HARP progress SPSC October 2007 Alain Blondel
Pion production yields p-Ta +
forward0.35 < < 1.55
backward1.55 < < 2.15
p
HARP progress SPSC October 2007 Alain Blondel
p-Ta
forward0.35 < < 1.55
backward1.55 < < 2.15
Pion production yields
HARP progress SPSC October 2007 Alain Blondel
In a first round of publications we usedbegin of fill data only(~1/3 of data)
HARP progress SPSC October 2007 Alain Blondel
3 GeV/c
5 GeV/c
8 GeV/c12 GeV/c
400 MCHF question: is 5 GeV/c (4 GeV kin energy) enough for the high intensity proton driver at CERN?(or elsewhere)
Neutrino factory optimization
HARP progress SPSC October 2007 Alain Blondel
Neutrinofactorystudy
d/d cross-sections can be fed into
neutrino factory studies
to find optimum design
Warning the above has fixed integration
range, but optimization may be
momentum dependent
yield/Ekin
+
-
+
-
HARP progress SPSC October 2007 Alain Blondel
MARS seems -- too optimistic for -- too pessimistic at low energy
p on Tantalum pion/(proton.(kinetic GeV))HARPHARP (full) vs MARS (dotted)-- absolute scale uncertain
Preliminary!MARS data courtesy S. Brooks
HARP progress SPSC October 2007 Alain Blondel
forward production only 0.35 < < 0.95 rad
comparison of and and yields for p-A for Be, C, Cu, Sn, Ta and Pb
Pion yields
HARP progress SPSC October 2007 Alain Blondel
A-dependence of and and yields for p-A for Be, C, Cu, Sn, Ta and Pb (3, 5, 8, 12 GeV/c)
A-dependence of Pion yields
HARP progress SPSC October 2007 Alain Blondel
In H2 elastic scattering events it is possible to comparethe predicted recoil to the observed one
==> direct measurement of dynamic distortions!!!
a model can be developped
HARP progress SPSC October 2007 Alain Blondel
LA Analysis: Full spill correctionsA phenomenological model has been developed and coded basing of the
fact that the force acting on each drift electron is equivalent to: a field system where ions, in a given angular section at R values internal to the
drift electron position, contribute to attract the drift electrons inwards a field system where ions, in a given angular section at R values external to the
drift electron position, contribute to attract the drift electrons outwardsThis model allows us to understand all the peculiar features of the TPC
dynamic distortions: The dependence of the distortion on the event number in spill The dependence of the distortion on tracks generated at different Z values in the
TPCThe Model has been developed and benchmarked as well the correction
algorithm
π-
π+
before afterns ns
d0 d0
HARP progress SPSC October 2007 Alain Blondel
Ratio of π+π- X-sections measured with and whitout the dynamic distortion corrections
HARP progress SPSC October 2007 Alain Blondel
Conclusions
HARP has taken a comprehensive set of data and we are producing pion production cross-sections with errors in the 4-8% range over a large fraction of phase-space
All DSTs are now ready for production pion cross sections for all targets and all beam momentum. Verification and publication of these results will require a lot of time and labor. Forward analysis for K2K and MiniBooNE has been important ingredient for the understanding of the neutrino fluxesForward Kaon production cross-sections remain to be produced are eagerly awaited
HARP progress SPSC October 2007 Alain Blondel
In the large angle region hard work for 5 years led to a good understanding of the chamber using experimental input. Extensive benchmarking of elastic scattering ensures a correct momentum scale at the level of 3% in the kinematic region relevant for pions.
The data relevant for the choice of proton driver for a neutrino factory have been published. Mission accomplished.
The large angle analysis using the full spill is ready and producing results.
HARP progress SPSC October 2007 Alain Blondel
Comments on the RBH report and subsequent situation
We do not agree with these statements.
we have produced 2 papers describing in detail our comments
Momentum scale in the HARP TPC G. Catanesi et al arXiv:0709.2806v1 [physics.ins-det], submitted to JINST
The Time Response of Glass RPCs to Heavily Ionizing ParticlesA.Artmonov et al, arXiv:0709.3756 [physics.ins-det], submitted to JINST
HARP progress SPSC October 2007 Alain Blondel
field reversal makes no visibledifference thatRBH expected..but shouldnt!
HARP progress SPSC October 2007 Alain Blondel
Investigation of RPC effect using elastic scattering H2
-- elastic scattering data @ 5 GeV -- use predicted momentum from elastic scattering kinematics (NO TPC!)-- calculate expected arrival in RPCs and compare with data
observation of a clear shift !
=> RPC calibrated for pions cannot be used for momentum benchmark with protons!!!
Hydrogen, 5GeV/c, from kinematics pad row 3
HARP progress SPSC October 2007 Alain Blondel
Once corrected for the resolution effects near the physical boundary (given by the need of the track to reach the TPC) the RPC Dt shift in LH2 data is consistent with the RPC shift in the other settings
Al13 12 8 5 3
Be12 9 8 5 3
Carbon 12 8 5 3
Copper12 8 5 3
H2
Lead12 8 5 3
Tin12 8 5 3
Ta12 8 5 3
HARP progress SPSC October 2007 Alain Blondel
the proton momentum in the high dE/dy region is independent of polar angle. (total momentum determines dE/dx)
This would not be the case for a sagitta biaswhich affects transverse momentum
HARP progress SPSC October 2007 Alain Blondel
In essence the interpretation of the RBH was that because of residual uncorrected dynamic distortions,the LH2 momentum calibration would be inapplicableto the rest of the data which would show a systematic difference from H2.
This is implausable but...not a priori impossible.
further findings...
1. the momentum calibration using full spill dynamic corrections is not modified at all; residuals (as requested by RBH) of tracks physically fixed to RPC show no significant trend. 2. The other sensitive indicators of momentum calibration (high dE/dy protons for instance) show complete agreement between H2 data and the rest.
HARP progress SPSC October 2007 Alain Blondel
Stability from LH2 target to other targets
consider average momentum of protons with dE/dx [7-8] MIPs
H2 setting
2%Al13 12 8 5 3
Be12 9 8 5 3
Carbon 12 8 5 3
Copper12 8 5 3
H2
Lead12 8 5 3
Tin12 8 5 3
Ta12 8 5 3
HARP progress SPSC October 2007 Alain Blondel
Concerning dE/dx: conclusion is not quantitative and no systematic error was assigned to the claim of 15% (±??) at 600 MeV/c (Dp/p is 25% at 1 GeV).Analysis should be done very carefully taking into accountbinning and resolution, and possibility of both scale and offset factors. We do not consider this to be conclusive
HARP progress SPSC October 2007 Alain Blondel
Having demonstrated the correctness of the LH2 benchmark both with and without dynamic correctionsthe stability of the momentum scale to other settings, andthe existence of a genuine RPC time biasfor heavy ionizing particles
We consider confident that our TPC momentum scale is correct within the quoted errors
HARP progress SPSC October 2007 Alain Blondel
Further steps
0. we believe that these discussions should take placeWithin the framework of the HARP collaboration
1. it is not clear to us what the extent of the real discrepancy between the CDP and HARP analyses is.This should be established on the basis of a track-by-track comparison (on going)
2. the effect of such a possible bias on the relevant cross-sections should be established! (how important is all this?)
HARP progress SPSC October 2007 Alain Blondel
Comments on the RBH report and subsequent situation
Issue of intellectual property: in the process we gave description of our findings, only to find them later in CDP work (RPC effect, dynamic distortion cross-over, elastic scatt.) with no reference to work of collaborators
From the later work on dE/dx, RPC, negative B polarity analysis we have to conclude that the results of the RBHreview which were unplausible are now most probably incorrect. There is not a 15% offset in HARP momentum reconstruction at 600 MeV/c