1. Production Studies: the HARP results WP2 December 2008
EURO ν
Production Studies: the HARP results WP2 December 2008
Maria Gabriella Catanesi
INFN Bari Italy

2. Outline Prospective & conclusions Why HARP ? The detector
HARP results:
K2K & MiniBoone fluxes
Super Beams & Neutrino Factory Design
Atmospheric fluxes ( < 15 GeV)
Hadron Production Models
Prospective & conclusions

3. Harp Inaugurates a new era in Hadron Production for Neutrino Physics:
Based on a design born for Heavy Ions physics studies
Full acceptance with P.Id.
High event rate capability (3KHz on TPC)
Built on purpose
Collaboration includes members of Neutrino Oscillation & Cosmic rays experiments
(124 Physicists from 20 institutions)
And makes measurements on specific targets of existing neutrino beams.

4. Existing measurements at the end of the millennium
1 GeV 10
100
1 TeV
Daughter energy
Boxes show importance of phase space region for contained atmospheric neutrino events.
Barton et. al.
Overall quoted errors
Absolute rates: ~15%
Ratios: ~5%
These figures are typical of this kind of detector setup
Abbott et. al.
Measurements.
1-2 pT points
3-5 pT points
>5 pT points
1 GeV 10
100
1 TeV
Parent energy
Eichten et. al.

5. HARP: Data taking summary
HARP took data at the CERN PS T9 beam line in
Total: 420 M events, ~300 settings
SOLID:
CRYOGENIC:
n EXP
K2K: Al
MiniBoone: Be
LSND: H2O 5%
50%
100%
Replica
10%
+12.9 GeV/c
+8.9 GeV/c
+1.5 GeV/c

6. Detector layout Forward spectrometer Large Angle spectrometer
30 mrad <  < 210 mrad.
750 MeV/c < p < 6.5 GeV/c
K2K,MiniBoone, Cosmic rays
Forward
spectrometer
Large Angle
spectrometer
Large Angle Spectrometer:
0.35 rad <  < 2.15 rad
100 MeV/c < p < 700 MeV/c
Super Beams - Nufactories
More details in the NIM paper “The Harp the CERN PS”

7. FORWARD ANALYSIS

8. FW: Momentum Resolution
ELASTICS
theta-p plane:
0.5
1.5 3 5 8 0.
0.1
0.2
TOF
elastics
empty target beam
TOF
BEAM
open: data
filled: MC

9. FW: PID principle
CAL
TOF
CERENKOV
CERENKOV
TOF

10. Relevance of HARP for K2K neutrino beam
One of the largest K2K systematic errors comes from
the uncertainty of the far/near ratio
pions producing neutrinos
in the oscillation peak
measured
by HARP
oscillation
peak
K2K far/near ratio
0.5
1.0
1.5
2.0
2.5
En (GeV)
K2K
interest
Beam MC confirmed by Pion Monitor
Beam MC

11. Far/Near Ratio in K2K
Predicted Flux Shape
Predicted Far/Near Ratio
Near Detector
Far Detector
HARP gives ~ factor 2 error reduction across all energies
Nucl.Phys.B732:1-45,2006
hep-ex/

12. MiniBoone : Harp Be 8.9 GeV 5% λπ+
Harp Forward Spectrometer Acceptance
(But also SCIBOONE)

13. HARP
Be 8.9 GeV/c data
Sanford-Wang
parametrization

14. More HARP data for accurate flux predictions coming:
main source of νe flux for MiniBooNE
K± production data
thick targets
π - production data
Direct measurement with rescattering and absorption
Anti-neutrino flux measurement p K p

15. - data needed for MiniBooNE antineutrino flux
Paper in preparation

16. Atmospheric neutrino fluxes
primary flux
Primary flux is now considered to be known to better than 10%
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
N2,O2
hadron
production
decay
chains

17. Model comparison: p+C→++X

18. Results for p+O2 or p+N2 cryo targets

19. More targets, more momenta
Available: Be, C, Al, Cu, Sn, Ta, Pb at 3, 5, 8, 12 GeV/c
Can be used for complete parametrizations or tuning of models
Low energy data useful for cascade calculations
These data were taken with lower statistics than the dedicated runs for K2K and MiniBooNE
Some example spectra:

20. HARP 3, 5, 8, 12 GeV/c

21. HARP 3, 5, 8, 12 GeV/c

22. HARP 3,5, 8, 12 GeV/c

23. HARP pA A-dependence

24. HARP p-A trends with A

25. Comparisons with models
Some examples

26. pAl @ 12.9 GeV/c versus GEANT4

27. Model comparison: p+C→+X
DPMJET: Glauber cascade, fits best for pi+
GHEISHA: parameterization for nucleus, interpolation and extrapolation
UrQMD: quantum mechanics, geometrical collision probability, parameterization for nucleons

29. π± Ta -> π± X 3 GeV/c

30. π± Ta -> π± X 5 GeV/c

31. π± Be -> π± X 5 GeV/c

32. Large Angle Analysis

33. LA Spectrometer performance
p-p PID with dE/dx
momentum
calibration:
cosmic rays
elastic scattering
momentum
resolution
PID:
dE/dx used
for analysis
TOF used to
determine
efficiency
p-e PID with dE/dx
elastic scattering:
absolute calibration of efficiency
momentum
angle
(two spectrometers!)

34. momentum scale efficiency The elastic scattering benchmark
[1/p (predicted-measured)]/(1/p)
Comparison of predicted
vs measured track allows
LA tracking benchmark
missing mass peak from
large angle proton track
(position of peak verifies momentum scale % shift is completely excluded)
efficiency
Momentum scale Sys. Error < 3%

35. Stability from LH2 target to other targets
consider average momentum of
protons with dE/dx [7-8] MIPs
H2 setting H2 Al
Carbon
Tin
2%
Copper Be
Lead Ta

36. Example of future projects
Primary energy, target material and geometry, collection scheme
maximizing the π+, π - production rate /proton /GeV
knowing with high precision (<5%) the PT distribution
A possible scenario: from 2.2 GeV/c to 8 GeV/c proton linac.
Phase rotation
longitudinally freeze the beam: slow down earlier particles, accelerate later ones
need good knowledge also of PL distribution 36

37. Neutrino factory study+ -
Ta Target Data + -
yield/Ekin
ds/dq cross-sections can be fed into neutrino factory studies to find optimum design
The optimal energy is between 5 and 8 GeV/c
published on EPJC

38. Low θ tracks in the TPC: (250 – 350 mrad)
We can measure these tracks but:
Worse resolution & lower efficiency

39. Neutrino factory study (cont’)
it’s also possible to enlarge the phase space
(if we accept larger errors)
On going analysis 39

40. π-π+ ratios for light and heavy nuclei

41. Pion yields
comparison of p+ and p- and yields for p-A for Be, C, Cu, Sn, Ta and Pb
forward production only < q < 0.95 rad p+ p-

42. Pion yields
A-dependence of p+ and p- and yields for p-A for Be, C, Cu, Sn, Ta and Pb (3, 5, 8, 12 GeV/c)
forward production only < q < 1.55 rad p+ p-

43. proton beams on long targets
Data analysed on tantalum and carbon targets (lead later)
Especially useful for the neutrino factory target
Interesting to tune models for re-interactions (and shower calculations in calorimeters etc.)
As for the thin targets, corrections for the absorption and re-interaction of the produced particles are made
NO correction is made for the absorption and re-interaction of the beam proton (this is what we want to measure)
Data are not directly applicable: our targets are 30mm in diameter: more re-interactions of the scattered proton

44. LONG C TARGET p-C p- PRELIMINARY forward 0.35 < q < 1.55
backward
1.55 < q < 2.15 44

45. 100% vs 5% TARGET FW and BW p-C p+ 100% l target 5% l target
PRELIMINARY

46. 100% / 5% TARGET bin-by-bin ratio 5 GeV/c beam: p-C p+/-
Large corrections !
If no effect from absorption of p: expect ratio = 1
If all interacting p are lost: expect ratio = 0.65 p- p+
PRELIMINARY

47. bin-by-bin ratio 12 GeV/c beam: p-C p+/- 100% / 5% TARGET
If no effect from absorption of p: expect ratio = 1
If all interacting p are lost: expect ratio = 0.65 p+ p-

48. 100% / 5% TARGET bin-by-bin ratio 5 GeV/c beam: p-Ta p+/-
If no effect from absorption of p: expect ratio = 1
If all interacting p are lost: expect ratio = 0.65 p+ p-

49. 100% / 5% TARGET bin-by-bin ratio 12 GeV/c beam: p-Ta p+/-
If no effect from absorption of p: expect ratio = 1
If all interacting p are lost: expect ratio = 0.65 p- p+

50. HARP publications Forward analysis In preparation :
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/ , 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, Eur.Phys.J.C52:29-53,2007.
Measurement of the production cross-section of pi+ in p-C and pi- C
Interactions at 12 GeV/c
M.G.Catanesi et al : Astroparticle Physics - volume/issue: 29/4 pp
Forward production of pi+/pi- in p-O2 and pN2 interactions at 12 GeV/C
M.G.Catanesi et al : Astroparticle Physics - volume/issue: 30/4 pp
Forward production of charged pions in the HARP experiment with incident pi+/pi- on nuclear targets
M.G.Catanesi et al : Accepted by Nuclear physics A
In preparation :
Full characterization of the MiniBoone/SciBoone  neutrino beam (pi-, kaon, protons, thick and replica target) Forward production of charged pions with incident protons on different nuclear targets Forward production of charged pions with incident protons and pions on different nuclear thick targets

51. HARP publications Large Angle analysis (Neutrino Factory measurements)
Measurement of the production of charged pions by protons on a tantalum target
M.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 targets
M.G. Catanesi et al, Eur. Phys. J. C53: ,2008
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, Eur. Phys. J. C54:37-60,2008
Large-angle production of charged pions in the HARP experiment with incident protons on nuclear targets :
M.G.Catanesi et al. Phys. Rev. C 77, (2008)
In preparation :
Large-angle production of charged pions in the HARP experiment with incident pions on nuclear targets : M.G. Catanesi et al. (Draft in preparation ) (beams 3 GeV/c GeV/c , Al, Be,C, Cu, Pb,Sn,Ta targets)
Large Angle production of charged pions with incident protons and pions on different nuclear thick targets

52. Conclusions
HARP has made important contributions to hadronic cross-section measurements relevant to neutrino experiments:
Aluminum results for K2K have used for final K2K publication.
Beryllium results for MiniBooNE and SciBoone are also finals. These measurements are already being used by the MiniBooNE collaboration.
Tantalum (and other targets results) for the Neutrino Factory studies are available
Carbon ,N2, O2 data for atmospheric neutrino fluxes are ready.
More production cross-section measurements are finished and can be used to tune hadron production models.
All the previous listed results have been already published but many new results will be coming soon … stay tuned !

53. backup

54. About the discrepancy between the HARP results and those produced by the so called “Dydak group”
Protons on Be

55. Protons on Be

56. About the discrepancy between the HARP results and those produced by the so called “Dydak group”
Protons on Be

57. In Summary We don’t believe in this hypothesis because
The Dydak group claims that the observed discrepancies should be interpreted as the consequence of a momentum bias (~15%) in our data
We don’t believe in this hypothesis because
This bias is excluded by the elastic scattering analysis
The discrepancy is visible only for π+
The discrepancy is visible only at low θ
The size of the discrepancy smootly depends from the beam energy
No shift is observed in the peak position
Any way the size of the effect is such that doesn’t change the optimal energy for the NF driver

58. Harp vs E910 (12 GeV/c P beam)