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How we improve the cross section measurement or how we Improve the analysis of MA. You measure (E m , q m , E had ) and reconstruct E n. If the flux is known to a few %, then the cross section can be measured:. Then, Q 2 distribution is plotted.

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How we improve the cross section measurement or how we

Improve the analysis of MA

You measure (Em, qm, Ehad) and reconstruct En.

  • If the flux is known to a few %, then the cross section can be

    measured:

Then, Q2 distribution is plotted.

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MA parameter is needed in the detector simulation

before we have a perfect cross section measurement.

But, how do we parametrize?

1. Vector form factors can be measured. N(e,e’),N(e,e’p)

2. Nuclear effects can be measured. N(e,e’),N(e,e’p)

To determine neutrino cross section, we need good pion cross

Section, namely good flux measurement. HARP,E910,MIPP

What are the systematic errors?

Overall normalization error?

Shape (spectrum) error? These two must be separated.

It is important to estimate the spectrum error, ie, energy dependent

errors (spectrum errors) are given. s(Pp, qp)

Unless you have confidence in your flux shape, flux dependent an alaysis

Should be avoided.

Flux error is 10-20%.Ds=DMA.

Statistical error in MA from shape analysis is +-3%.

Shape is not a simple dipole.

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Ds=DMA

Problem 1. Statistical error in MA is +-3%.

Shape is not a simple dipole.

Flux error is 10-20%.

  • If the flux is known to a few %, then the cross section can be

    measured:

Then, Q2 distribution is plotted.

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Pauli Bloching effect

Nuclear effects are large in the low Q2 region, where the cross section is large.

En=1.3 GeV,kF=220 MeV/c

ds/dQ2

n

m-

Quasi-elastic

q

W/o Pauli effect

n

p

P

p

W/ Pauli effect

Total 8%

0.5 1.0

ds/dQ2

If P <kF , suppressed.

n

m-

D production

10-15% suppression

At low Q2

Total 3% reduction

q

p

D

P

p

P

p

W

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Charged current quasi elastic scattering
Charged-Current Quasi-elastic Scattering

  • This is the simplest and the most important reaction.Calculation by Ch.L.Smith et al. with MA=1.0.

_

s(nmpm+n)

s(nmnm-p)

1.0

1x10-381.0

(cm2)

Pauli effect ~8%

0.1

1.0

10.

50.

0.

0.1

1.

10.

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Single pion production cross section
Single Pion Production Cross Section

Prediction = Rein-Sehgal MA=1.2 GeV/c2

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1x10-381.0

(cm2)

0.0

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