A study to clarify important systematic errors

1
A study to clarify important systematic errors

• A.K.Ichikawa, Kyoto univ.

We have just started not to be in a time blind
with construction works. Activity members come
from KEK, Kyoto univ and Tokyo univ.
2
Hiraide study in 2004http//www-he.scphys.kyoto-u
.ac.jp/member/hiraide/t2k/index.html

• Systematic shifts on (sin22q23,Dm232) are
  evaluated with following systematic errors.
• Flux normalization uncertainty (10)
• Non-QE ratio uncertainty (20)
• Energy scale uncertainty (4)
• Spectrum shape uncertainty (FLUKA/MARS)
• Spectrum width uncertainty (10)

3
Systematic shift
K.Hiraide
OA2.5deg
d(sin2 2q)
d(Dm2)
MINOS 90
shape
nqe
esk
width
width
norm
stat.
stat.
esk
norm
shape
nqe
Various systematic shifts are shown as a function
of true Dm2. Dashed lines indicate the size of
statistical error.
4

• This was a very instructive study. Direct
  reduction of above systematic errors is very
  important.
• Indirect reduction of systematic errors by
  cancellation btw. near and far observation is not
  evaluated.
• Near to Far Extrapolation method should be
  studied. A new method may be useful if that is
  found to be robust against systematic
  uncertainty.
• Default Far/Near ratio
• Matrix in (Enfar, Ennear) plane.
• Using parents(p,K) (p,q) distribution
• Some of the systematic errors is not evaluated.
  (e.g. beam related ones.)

5
Cancellation of syst error on N11exp
N11exp(f)
NSKMC(f)
?NKTMC(f)
From K2K
6
Contribution of syst. errors on spectrum
From K2K
Spec.
nQE/QE
Spec.nQE/QE
Total
SK Escale
eSK
F/N
7
K2K-II ne appearance searchError on backgrounds
from nm
NC1p0/CC ratio 6,-7
NC/CC ratio(non-NC1p0) -3
p0 energy spectrum -8
coherent p0 model 3,-10
p0 mass cut 19,-17
water properties -6
neutrino flux at SK -6
non-QE/QE ratio -1
detector efficiency -6
single electron selection 7, -8
Total 39,-24
Super-K intrinsic
8
Short term goal of this study

• Find the best near to far extrapolation method
• The best one would varies depending on statistics
  and information from NA61 and ND measurements.
• Can ND mesurements constrain hadron production
  uncertainty when there is uncertainty on netrino
  interaction?
• Make oscillation analysis tool for T2K based on
  the K2K method.
• See next slide.
• Clarify the importance of following systematic
  errors as a function of statistics
• Hadron production
• Compare GFLUKA, MARS and FLUKA2007
• Getting reasonable error matrix on flux by
  assuming reasonable uncertainty in (p,q)
  distribution
• After NA61 results come, this will be replaced.
• Beamline origin (misalignment etc.)
• Neutrino interaction
• Energy dependent non-QE/CCQE ratio, NC/CC ratio
• Super-K intrinsic
• energy scale and normalization (comes from FV,
  PID etc.)
• For ne appearance, statistical and Super-K
  intrinsic error would be dominant. Still update
  of p.7 table with T2K off-axis flux is important
  to confirm this.

9
Likelihood
From K2K
Normalization term
Shape term for FCFV 1Rm
Systematic parameter constraint term
10
T2K Near to Far extrapolation Matrix
En(Super-K)
Robustness against the hadron production
uncertainty will be checked. En(Super-K) v.s.
En(on-axis) will be made, too.
Very Preliminary
En(Off-axis ND280)
K.Sakashita