HARP progress SPSC October 2007 Alain Blondel Progress report from HARP Overview of new results Forward analysis Accelerator Neutrino Beam ( K2K, MiniBooNE),

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



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


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 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 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 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 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


FORWARD ANALYSIS


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


PID principle

CERENKOV

TOF

CAL

TOF

CERENKOV



K2K Flux prediction for near and far detectors and far/near ratio

note improvement over existing data

errors are smaller and safer


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 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 Be 8.9 GeV/cdata Sanford-Wang parametrization


Systematic errors here: forward 8.9 GeV/c Berylium (MiniBooNE)

improvements in-- tertiary interactions(use our own pC and C data)-- PID

Al data


comparison of Be with existing data


- data needed for MiniBooNE antineutrino flux

Panman


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


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


p+C @ 12 GeV/c

• leading particle effect

• stat.syst. errors

●

○

log scale

Draft in preparations


Model comparison: p+C→++X


Model comparison: p+C→+X


+C @ 12 GeV/c(lower statistics)


+C @ 12 GeV/c(high statistics)


Preliminary results for O2 N2 cryo targets available


LARGE ANGLE ANALYSIS


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)


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


“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+-.


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


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


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!)


cryogenic H2 target


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)


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


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)


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



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


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


Pion production yields p-Ta +

forward0.35 < < 1.55

backward1.55 < < 2.15

p


p-Ta

forward0.35 < < 1.55

backward1.55 < < 2.15

Pion production yields


In a first round of publications we usedbegin of fill data only(~1/3 of data)


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


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

+

-

+

-


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


π-/π+ ratios for light and heavy nuclei


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


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


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


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


The model eliminates the event-in-spill dependence


p-Ta π whitout and with Dyn. Dist. Corrections


Ratio of π+π- X-sections measured with and whitout the dynamic distortion corrections


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


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.


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


field reversal makes no visibledifference thatRBH expected..but shouldnt!


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


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


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


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.



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


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


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


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?)


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

Documents

HARP progress SPSC October 2007 Alain Blondel Progress report from HARP Overview of new results Forward analysis Accelerator Neutrino Beam ( K2K, MiniBooNE),