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A preliminary estimate of the beam e’s from antineutrinos

David Jaffe, Pedro Ochoa

December 7th 2006

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Data used:

Horn-off: LE-10, Birch, 2.77x1018 POT (couple of days Feb-2006)

Horn-on: LE-10, Birch, 8.15x1019 POT (Oct 2005 -Jan 2006)

MC used:

Horn-off: LE010000, Carrot, 1.32x1019 POT

Horn-on: LE010185, Carrot, 4.17x1019 POT

Data and MC used

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Preliminary results of from +:

from + decay

E < Ecut

data-(Fit or Scaled) MC, Ecut < E < 30 GeV

raw MC 1553.7 ± 55.1 (stat) 283.0 ± 23.0 (stat)

reweighed MC 1538.2 ± 54.8 (stat) 386.5 ± 32.4 (stat)

Scale method 1 4685.4 ± 367.4 (stat) -5914.9

Scale method 2 4628.8 ± 367.8 (stat) -5991.6

Stan’s method 3163.6 ± 1122.0 (stat) -243.5 ± 1169.1 (stat)

Scale method 3 3820.2 ± 374.5 (stat) 584.3 ± 339.5 (stat)

Scale method 4 6392.8 ± 355.1 (stat) 412.4± 341.4 (stat)

Fit method 1735.5 ± 380.3 (stat) -357.1 ± 351.8 (stat)

Note: talked with Zarko about using new neutrino-antineutrino combined fit in modified energy range for nubars. In progress.

Should be real nubars from + if

data/MC from horn-off is trust-

worthy in this region

Should be ~0 by construction

Should be real nubars from +

Expected to be highly

negative by construction

Details can be found in backup slides and in minos-docs 2421 and 2218).

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Systematics

In addition, uncertainties when going from to e: from + selection efficiency: no systematic yet. ()/(e):

Error in fit: no current estimate for SKZP “a la Boston” with antineutrinos. Will have one with new fit.

How accurate is the Horn-off disagreement between data and MC to scale the Horn-on MC? No systematic yet

Purity of antineutrino sample: see minos-doc-2205

For the atmospheric paper, Hugh G. estimated 13.5 % uncertainty in ()/()

(see minos-doc-1424). Should be almost identical for ()/(e)

Main systematics for from + are:

Deconvolution to extract e spectrum: no systematic yet

ND-FD extrapolation: no systematic yet

Cross-section shape uncertainty: see talk tomorrow

Reconstruction efficiencies for and e’s: small effect (?)

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Doing the numbers

e from +

e

from +, 0 < E < 30 GeV

Stan’s method 2920.1 ± 1677.2(all)

Fit method 1378.3 ± 532.8(stat)

Combination of scaling methods 1,2 and 4 gives:

5235.7 ± 629.6(stat) ± 818.5 (syst)

from +:

Necessary parameters from MC (all below 30 GeV):

With Stan’s method, at 1x1019 POT we get:

e’s from +, fid vol e’s from +

Stan’s method 3,391.1±2017,4 17,091±10,178.8

Raw MC 2,121.1±52.55(stat) 10,691.4±118.0(stat)

- Selection efficiency for from + is 31.38 % ± 1.9% (stat) - Ratio of e’s from + to ’s from + is 2.97±0.14(stat) ±0.40(syst) - Ratio of e’s from + in detector to those in fiducial volume is 5.04±0.14(stat)

(this is reconstructed e’s from +, not all e’s that go through the detector)

Assume we are dominated by statistics

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Backup

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Reweighting nubars from +

from m+, raw MC from m+, reweighted MC

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Scaling method 1

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Scaling method 2

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Scaling method 3

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Scaling method 3-alt (no fit to ratio)

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Scaling method 4

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Fit method

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(Fit method 2 – discredited)

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(Fit method 3 – discredited)