Using the pHE data to measure the beam n e ’s from m + decay
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1 Using the pHE data to measure the beam e ’s from + decay David Jaffe and Pedro Ochoa June 14 th 2007 Reminder Updated Statistical error Horn 1 systematics Summary
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Using the pHE data to measure the beam n e ’s from m + decay. David Jaffe and Pedro Ochoa. Reminder Updated Statistical error Horn 1 systematics Summary. June 14 th 2007. - Fit using MC shapes. Scale n ( m + ) LE and n ( m + ) pHE by parameters parLE and parHE. - PowerPoint PPT Presentation
Transcript of Using the pHE data to measure the beam n e ’s from m + decay
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Using the pHE data to measure the beam e’s from + decay
David Jaffe and Pedro Ochoa
June 14th 2007
Reminder Updated Statistical error Horn 1 systematics Summary
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Reminder
x parLE(+)pHE
(,K)pHE-(,K)LE
x parHE(+)LE
Procedure: - Take pHE-LE difference. Correct for
- Fit using MC shapes. Scale (+)LE and (+)pHE by parameters parLE and parHE.
Previous study (doc-2909) showed that pHE background is not big concern.
Main systematics associated with this measurement: C=(,K)pHE-(,K)LE correction. Background in nubar selection.
But the previous assessment of C was too pessimistic and done with too few statistics, so it is redone here.
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Update on statistical error
Previous study (doc-2783) assumed 2.0x1019 POT of pHE data and a statistical error of ~13% in the measurement was quoted.
But more precisely, the pHE data taken after the 2006 shutdown corresponds to 1.6x1020 POT. So repeated the fit with this number:
New statistical error in (+)LE is 15%.
90% C.L.
68.3% C.L.
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Horn 1 systematics
How well can we determine C = (,K)pHE- (,K)LE?
So obtained ratios of spectra with systematics over nominal spectra using gnumi:
Ex: horn1 current increase by 2% in pHE
neutrino beam
Good agreement with pbeam
Systematics considered are:
horn 1 offset 1.0 mm
horn current offset 1%
Target displacement 1cm
Work by David suggests C mostly affected by horn1 & target geometry, as one would expect (minos-doc-2841)
Obtained gnumi ratios are shown in the next 5 slides.
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Horn current -1%
le010z185i le250z200i
nominalwith systematic
(,K-) (,K-)
(+)(+)
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Horn current +1%
le010z185i le250z200i
nominalwith systematic
(,K-)(,K-)
(+)(+)
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Horn offset by 1mm
le010z185i le250z200i
nominalwith systematic
(,K-)
(+)
(,K-)
(+)
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Target in LE position -1cm
le010z185i
(,K-)
nominalwith systematic
(+)
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Target in LE position +1cm
le010z185i
(,K-)
nominalwith systematic
(+)
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Converted these ratios to reconstructed energy using the ntuples:
Ex: target position increased by 1cm in LE
Convert to Ereco
)(),(
),(
185010
185011reco
izle
izle EKv
Kv
Used these ratios(Ereco) to scale the spectra in our feasibility study and obtain systematic shifts.
Nominal spectra are used to do the fit which contains spectra including these systematics.
Infinite MC and LE data statistics are assumed.
(no events in first bin)
)(),(
),(
185010
185011true
izle
izle EKv
Kv
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Example: Horn offset by 1mm
LEpHE KvKv ),(),(
Systematics:
Results of fit:
with systematicsnominal
with systematicsresult of fit
pHE-LE corrected for background and nominal C
Bias of 3%
(+) pHE
Bias of 3%
(+) LE fit
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Summary of biases in measurement:
Also need to add the error associated with hadron production.
Horn I -1% Horn I +1% Horn offset 1mm LE Target -1cm LE Target +1cm
Bias in parLE -15% -9% 3% 1% 1%
Bias in parHE -14% -14% 3% -6% -6%
This assumed same horn conditions for pHE and LE running (except for target displacement). If that is not the case need to work with other combinations:
Horn I -1% Horn I +1% Horn offset 1mm
Applying systematics to LE beam only
Bias in parLE -4% -5% 6%
Bias in parHE -6% -9% 6%
Applying systematics to pHE beam only
Bias in parLE -10% -3% -3%
Bias in parHE -9% -5% -2%
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The statistical error of the measurement with 1.6x1019 POT of pHE data is ~15%.
Summary & Ongoing work
Measurement of (+)pHE is more affected by horn1 & target systematics than (+)LE. Fortunately we don’t care.
Main sources of systematic errors seem to be under control.
Next step: carry out the measurement
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Backup
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Horn current -1%
LEpHE KvKv ),(),(
Systematics:
Results of fit:
with systematicsnominal
with systematicsresult of fit
pHE-LE corrected for background and nominal C
Bias of -14%
(+) pHE
Bias of -15%
(+) LE fit
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Horn current +1%
LEpHE KvKv ),(),(
Systematics:
Results of fit:
with systematicsnominal
with systematicsresult of fit
pHE-LE corrected for background and nominal C
Bias of -14%
(+) pHE
Bias of -9%
(+) LE fit
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Target -1cm
LEpHE KvKv ),(),(
Systematics:
Results of fit:
with systematicsnominal
with systematicsresult of fit
pHE-LE corrected for background and nominal C
Bias of -6%
(+) pHE
Bias of 1%
(+) LE fit
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Target +1cm
LEpHE KvKv ),(),(
Systematics:
Results of fit:
with systematicsnominal
with systematicsresult of fit
pHE-LE corrected for background and nominal C
Bias of -6%
(+) pHE
Bias of 7%
(+) LE fit
