HARP measurements of pion yield HARP measurements of pion yield for neutrino experiments for neutrino experiments Issei Kato (Kyoto University) for the HARP collaboration Contents: 1. HARP experiment • Physics motivations • Detector status 2. First physics analysis for K2K target 3. Summary NuFact 04 @ Osaka
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HARP measurements of pion yield for neutrino experiments
HARP measurements of pion yield for neutrino experiments. NuFact 04 @ Osaka. Issei Kato (Kyoto University) for the HARP collaboration. Contents: HARP experiment Physics motivations Detector status First physics analysis for K2K target Summary. Introduction - motivations -. - PowerPoint PPT Presentation
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HARP measurements of pion yieldHARP measurements of pion yieldfor neutrino experimentsfor neutrino experiments
Issei Kato (Kyoto University)for the HARP collaboration
Contents:
1. HARP experiment• Physics motivations• Detector status
Hadron/electron separationHadron/electron separation(Reused from CHORUS)• Pb/fibre: 4/1 (Spaghetti type)
– EM1: 62 modules, 4 cm thick– EM2: 80 modules, 8 cm thick
• Total 16 X0
• Energy resolution
electronselectrons
pionspions
3 GeV3 GeV
datadata
)(%23GeVEE
E EM Energy (a.u.)
Ene
rgy
EM
1/E
M2
Forward AnalysisForward Analysis- for K2K target -- for K2K target -
Forward TrackingForward Tracking
dipole magnetNDC1 NDC2
B
x
z
NDC5
beam
target
Top view
11
22NDC3
NDC4
Plane segment (2D)
33
• Categorize into 3 track types depending on the nature of the matching object upstream the dipole1. Track(3D)-Track(3D)2. Track(3D)-Plane segment(2D)3. Track(3D)-Target/vertex constraint
To recover as much efficiency as possible To avoid dependencies on track density in 1st NDC module
If a particle reaches the NDC module 2,the particle is accepted.
2 4 6 80
0.2
0.4
0.6
0.8
1
P(GeV/c)
acce
ptan
ce
0.2
0.4
0.6
0.8
1
acce
ptan
ce
-200 0 200 (mrad)
K2K interest
MCMC
MCMC
downupdowndown
recp
acc
downtrack
NN
NN
.
Downstream trackingefficiency ~98%
Up-downstream matching efficiency ~75%
Tracking efficiencyTracking efficiency
track is known at the level of 5%
Green: type 1
Blue: type 2
Red: type 3 Black: sum of normalized
efficiency for each type
Total Tracking Efficiency
0 2 4 6 8 10
0.2
0.4
0.6
0.8
1.0
0.2
0.4
0.6
0.8
1.0
-200 -100 0 200100P (GeV/c) x (mrad)
Tot
al tr
acki
ng e
ffici
ency
Tot
al tr
acki
ng e
ffici
ency
Total tracking efficiency as a function of p(left) and x (right)computed using MC with 2 hadron generators properly Both hadron models compatible (except for |x| < 25 mrad)
Need more study for this region.
Dependence of tracking efficiencyDependence of tracking efficiencyon hadron production modelson hadron production models
0 2 4 6 8 10P (GeV/c)
0.2
0.4
0.6
0.8
1.0
0.2
0.4
0.6
0.8
1.0
-200 -100 0 100 200x (mrad)
exclude |x| < 25 mrad, this time
Tot
al tr
acki
ng e
ffici
ency
Tot
al tr
acki
ng e
ffici
ency
Particle identificationParticle identification
e++
p
number of photoelectrons
inefficiency
e+
h+
0 1 2 3 4 5 6 7 8 9 10
p
P (GeV)P (GeV)
e
k
TOF CERENKOV CALORIMETER
3 GeV/c beam particles3 GeV/c beam particles
TOFCERENKOV
TOF ?CERENKOV
CERENKOV
CALORIMETER
TOF
CERENKOV
CAL
+
p
datadata
ekpphe
phephe
pPEEpPNpPpP
pPEEpPNpPpPEENpP
,,,21
2121
)|()|,,()|,()|,(
)|()|,,()|,()|,( ),,,,|(
tof cerenkov calorimeter
momentumdistributionUsing the Bayes theorem:Using the Bayes theorem:
1.5 GeV 3 GeV 5 GeV
datadata
Forward PID: Forward PID: efficiency and purity efficiency and purity
1.5 GeV 3 GeV 5 GeV
Typ
e1
Typ
e2T
ype3
Typ
e1
Typ
e2T
ype3
Typ
e1
Typ
e2T
ype3
Typ
e1
Typ
e2T
ype3
Typ
e1
Typ
e2T
ype3
Typ
e1
Typ
e2T
ype3
0
0.6
0.4
0.2
0.8
1
pion
eff
icie
ncy
0
0.6
0.4
0.2
0.8
1
pion
pur
ity
Iteration: dependence on the prior removed after few
iterations
truej
obstruej
tj NN /)( obs
jobstrue
jt
j NN /)(
we use the beam detectors to establishthe “true” nature of the particle
Use K2K thin target (5%Use K2K thin target (5%))• To study primary p-Al interaction• To avoid absorption / secondary interactions