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July 4, 2002 n Fact02 @Imperial College London. Translation from Near to Far at K2K. T.Kobayashi IPNS, KEK for K2K beam monitor group (K.Nishikawa, T.Hasegawa, T.Inagaki, T.Maruyama, T.Nakaya, ....) - PowerPoint PPT Presentation
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1
Translation from Near to Far at K2K
T.KobayashiIPNS, KEK
for K2K beam monitor group(K.Nishikawa, T.Hasegawa, T.Inagaki, T.Maruyam
a, T.Nakaya, ....)Especially for T.Maruyama(KEKChicago) who played major role in PIMON construction/measurem
ent/analysis
July 4, 2002Fact02@Imperial CollegeLondon
2
00.20.40.60.81
1.21.41.6
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
Strategy of K2K
Pion monitor(PIMON)
MUMON FD
+
Target+Horn
200mdecay pipe
SK
100m ~250km
10 2 43 5E (GeV)
4
8
12
x1010
10 2 43 5E (GeV)
2
4
6
8x104
spectrum@productionspectrum @SK
measure w/ FDmeasured by PIMON
(MC)
(MC)
(MC)w/o osc.
w/ osc?
Extrapolate bymultiplying ratio(≠0)
arb.
uni
t
arb.
uni
t
3
What’s new in the treatment of far/near extrapolation
• Before– Observable for osc. analysis:
• total # of events
– added syst. error from each energy bins linearly (= 100% positive correlation) to be safe.
• New– Observables for osc. analysis
• total # of events,
• Erec spec. shape for 1-ring -like events
– Correlation for far/near ratio btw energy bins are taken into account
4
Far/Near ratio in oscillation Far/Near ratio in oscillation analysis (method1)analysis (method1)
)()()( fLfLfLL systshapenormtot systematics parameters
),,,,,,( 116F/N nnEsksknQE ffffffff spec
nQE/QEFar/near
SK(efficiency)SK Enegry scale
Overall Norm ErrorFor Jun99 and Nov99-
Maximum Likelihood Method
5
ji
KTijijji
MCKTi
ji
SKijijji
MCSKNiFi
obsKT
MCKT
oscMCSKobs
KT
fEf
fmPEff
N
fN
PfNNN
,
,
22/
exp
)()(
)()2sin,()(
)(
),(
Normalization termNormalization term
))(,( exp fNNPoissonL obsnorm
i: energy bin indexj: processes (=QE, nQE)
Spectrum meas. in FD(fi) cancels first orderbut far/near ratio fF/N does not.
6
EErecrec spectrum shape term for FC spectrum shape term for FC
1R1R
29
1
)(i
recishape EPL
P: reconstructed E distribution for 1R (gen’ed by using MC)
Total 29 events for Nov99~ data
true
truerecnQE
trueRnQE
truenQEnQE
truerecQE
trueRQE
trueQE
trueSK
rec
dEEErEEf
EErEE
EEP
,
,1
1
22/ ,2sin mPRffE oscNF
MCFD
meastrueSK
Detector response from MC
7
Systematic constraint termSystematic constraint term 22
211
211
26
26
1
/1//
,1
,
2/exp
2exp2exp
2/exp
2/exp
2/exp
EskEsk
nnnn
SKSKTSK
NFNFTNF
nQEFDTnQEsyst
f
ff
fMf
fMf
fMfL
MFD, M, MSK: error matrix of syst. errors.n6: overall norm. err. for Jun99 evts)
n11:overall norm. err. for Nov99~ (=5.34%)
Esk: SK Enery scale error (3%)
1 ff
Far/near ratio
8
Qeustions
• Central values of far/near ratio (relative to MC prediction)
fF/Ni
• Correlation of far/near ratio btw. energy bins (error matrix)
M
9
A tool:Pion Monitor (PIMON)
To decay volume
From 2nd Horn
910
Blind
Beam window
470
230
200
900
2100
2750
Sphericalmirror
Photo detector 20 PMTs
600
200
110
910
Top view
Beam view
Pion monitorGas volume
~ Design on May 11,'98 ~
1 9 0
N(p, ) Neutrino flux (E) at any distanceusing only decay kinematics
R(E)≡SK(E)/FD(E)as a result of pion monitor
Gas Cherenkov detector
to avoid signal from 12GeV protons insensitive to p <2GeV (E<1GeV)
PMT array
10
Strategy to obtain fF/N, error matrix
• Above 1GeV PIMON• Below 1GeV Beam MC(Sanford-Wang parameterizati
on fitted to previous data) validated by PIMON measurement at >1GeV
• Error matrix
0
0
MC
PIMON
1GeV
1GeV
(4x4)
(2x2)
MC part: Fit previous pion production data below ~2GeV/c move paraemters within error get error matrix
No correlation w/ PIMON part
11
Pion Monitor Results
p
w1 w2 w3 w4 …..: :
: :
12
Pion Monitor Result(relative weight)
- 5
- 4
- 3
- 2
- 1
0
1
2
3
4
5
2 3 4 5 6 7P i o n m o m e n t u m ( G e V / c )
Pio
n an
gle
(*10
mra
d)
beam axis
+
13
Pion distribution to far/near ratio (incl. error matrix)
- 5
- 4
- 3
- 2
- 1
0
1
2
3
4
5
2 3 4 5 6 7P i o n m o m e n t u m ( G e V / c )
Pio
n a
ngl
e (*
10m
rad
)
Relative weight Wi(i=1~50)
ijE
50x50 error matrix on weight
i
jij dW
dRU
From PIMON fitting
UEUE TR
(4x4) (4x50) (50x50) (50x4)
E
jSKFDi W,
WWR
W
FDi
SKii
jj
SKFDi
SKFDi
50
1
,,
Contribution to fluxfrom each p- bin(by MC. To 1st order,depend only on decay kinematics &geometry
FD,SK flux
Ratio as func. ofweights
Dependenceof R on W (50x4 matrix)
Error matrixtransformationfrom weight far/near ratio
14
Other systematic errrostreated in matrix form as described
1. move syst. parameter within error2. Check correlation btw energy bins
Ri
Rj
15
spectra from Pion Monitor Measurement
Agree with MC very well.
16
PIMON result for F/N ratio
Good Agreement!
0
0 .1
0 .2
0 .3x 1 0
-5
0 1 2 3E ( G e V )
Fa
r/n
ear
rati
o
P io n m o n ito r
N e u trin o B e a m S im u la tio n
In te g ra te da b o v e 2 .5G e V
17
Far/Near Error MatrixFar/Near Error Matrix
0-0.5 0.5-1 1-1.5 1.5-2 2-2.5 2.5-
“sqrt” of error matrix (%)
ijij MM sign
Beam MC PIMON
18
Summary of systematic errors on total Summary of systematic errors on total # of events w/o osc.# of events w/o osc.
Center: 80.1evts (%)
Jun99
(4.55evts)Total
+1.0%
0.9%
Nov99~
(75.5evts)
Spectrum+0.6%
0.6%
nQE/QE+0.5%
1.1%
Far/Near+4.9%
5.0%
Norm 5.0%
Total+7.7%
6.7%
19
Summary• K2K uses pion distribution measured in-situ(>1G
eV) and beam MC(<1GeV) for spectrum extrapolation
• The beam MC is validated by the PIMON measurements
• Correlation of far/near ratio btw energy bins is taken into account (instead of linear sum = 100% positive correlation
• Still far/near ratio is major source of systematic error
• Expect precise data from HARP (measurement in Aug.26~). Many many thanks to HARP collaborators
20
Syst. error: far/near spectrum diff.Typical OA beam(80mDV)
280m
295km
K2K case (MC)
FD(300m)(xLSK
2/LFD2)
SK
Important not only for disappearance,but also for sig/BG estimation for e search
Large(~x2) effectaround peak!!
21
4.81019 POT for Analysis
200kA 250kA
POT
PIMON meas.
22
Stability of Energy Spectrum
Muon Energy of MRD events
Muon Energy in KT on ’01, ‘00
Everymonths
23
Exp’ed EExp’ed Erecrec spectrum for 1R spectrum for 1R estimated by estimated by
FD measurementsFD measurements
24
PIMON in target station
25
26
K2K osc. analysis overview
spectrum @ production
near/far extrapolation
oscillation probability
neutrino interaction in water
detector responce(1kt, scifi) detector responce(SK)
FD observation1KTScifi
SK observationtotal # of eventsE
rec spectrum shape(1ring -like events)
PIMONp- dist
Want to know this!!
Near Far
(1R)