Results of the HARP experiment Part 2 I.Boyko, Yu.Nefedov.
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Transcript of Results of the HARP experiment Part 2 I.Boyko, Yu.Nefedov.
Results of the HARP experimentPart 2
I.Boyko, Yu.Nefedov
Particle identification
π+π-
p
The HARP split
• At the begin of the data analysis, HARP broke into two parts over a deep split of opinion on quality of work, working methods, and professional ethics.– 'HARP Collaboration' or 'Official HARP' (OH)– 'HARP-CDP group' (CERN, Dubna, Protvino)
• In this seminar, we represent HARP-CDP• Between OH and HARP-CDP, only the raw data
and the computing infrastructure are common. The analysis strategies and software are totally independent.
The “500 ps effect”
• Citation from 2008 JINST 3 P04007: `The remaining difference observed … is of the order of (150±100) ps at 450 MeV/c’
ΔT = 480-130 = (350±40)ps
480±30 ps
130±20 ps
Δt
(ns)
What is wrong with OH calibration
• Momentum bias Δ(1/PT) = 0.3 (c/GeV)
• Poor momentum resolution σ(1/PT) = 0.55-0.65 (c/GeV)– CDP: 0.20-0.25 (c/GeV)
• TOF resolution: σ(TOF) = 305 ps– CDP: σ(TOF) = 175 ps
• Unphysical “500 ps effect” in RPC
Comparison of GEANT4 hadronic models with the HARP-CDP data
GEANT4 (LHEP) angular spectrum of π+ produced by 8.9 GeV protons
GEANT4 versus HARP-CDP data
The “LSND puzzle”
On the “LSND puzzle”
• LSND: anomalous 4 σ signal of anti-νe from the interactions of Ekin=800 MeV protons in water.
• LSND interpretation: – anti-νμ → anti-νe oscillations– with Δm2 ~ 1 eV2
• Sterile neutrinos?• MiniBooNe disagrees with
LSND• Question: is π-/ π+ ratio correct?π+
π-
μ+
νμ
μ-
_νμ _
νe
νμ
e-
e+
_νμνe
p+H2O
π-/ π+ ratio: LSND vs HARP-CDP
LSND parametrizationLSND parametrization
Production of hadrons by +8.9 GeV/c and -8.0 GeV/c
proton and pion beams on 5% λ Be target
What we measure
p π+ π- K+ d
p
π+
π- -
Secondary particle
Bea
m
Some cross-section plotsPositive pion beamNegative pion beam
Comparison with OH
Comparison with E910
E910: 1.5 m long flat-geometry TPC
• HARP-CDP is going to publish lots of precise cross-sections of hadron production on nuclei.
• 'Official HARP' publish cross-sections that are wrong by factors up to two (to our regret, with participation of JINR Dubna authors).
• 'Official HARP' consciously ignore:– the conclusions of the CERN/INFN Review Board for HARP
(chairman L. Foa): '...The RBH finds clear evidence for a significant momentum bias in the OH analysis...the RBH finds no evidence if any significant momentum bias in the CDP analysis...'
– the conclusions of the CERN-SPSC Review (chairman J. Dainton): '...This calls into question the validity of the results in recent publications by the HARP collaboration of their large angle data, based on analysis (a)[=OH]...‘
– our published calibration work of the TPC and the RPCs
Backup slide