nd data/mc comparisons

P. Vahle, Fermilab Oct 2005

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ND Data/MC Comparisons

Patricia VahleUniversity College London

Fermilab Collaboration Meeting October, 2005

Outline:I. Things (I think) I understandII. Things I don’t understand


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Cuts Applied

Beam Quality Cuts• tor101 > = 0.1e12 pot/spill • tortgt > = 0.1e12 pot/spill • horizontal beam width < = 2.9 mm • vertical beam width < = 2.9 • -2 mm < = horizontal beam position at target < = 0 mm • 0 mm < = vertical beam position at target < = 2 mm • closest beam monitoring record witin 2 sec. of snarl

time • horn current > = 50 A


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Cuts Applied

• ND Data Quality Cuts• event vertex in "The Pittsburg Fid. Region"

– event vertex x position < 2.4 m – 0.6 m < event vertex z position < 3.56 m – 0.3 m < event vertex u position < 1.8 m – -1.8 m < event vertex v position < -0.3 m – event vertex 0.8 m away from coil hole

• trk.fit.pass==1 • track fit chi2/NDF < 10 • difference in planes between the u vertex and v vertex < 6 planes • number of tracks == 1 • absolute value of error in (q/p) divided by q/p < .2 if muon momentum is

obtained by curvature (not a stopper). • no other event with vertex time within 50 ns of event in question • 90% of shower energy must be in fully instrumented planes • muon charge < 1 • track vertex z position > 0.6 m


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Ely Energy Distributions

•Black—LE•Red—pME•Blue—pHE•Solid—data•Bands—MC with beam sys. errors

Data and MC in pME and pHE beams don’t match!


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Ely MC

• Old GMINOS executable, no target offsets to wfluk routine

• Black—Old ME MC• Pink—ME flux,

tgtshift=0 • All fixed in R1.18 MC• Only affects ME and

HE


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Eν Distributions Now

Much Better!

•Black—LE10•Red—pME•Blue—pHE•Solid—data•Bands—MC with beam sys. errors


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Events Accepted

Beam Config POT Events Accepted Events/1e17 POT %NC Contamination

LE10 Data 8.7e18 90531 1043.0

LE10 MC 2.4e18 25154 1061.8 8.6

pME Data 8.0e17 16457 2053.6

pME MC 3.4e18 74579 2169.1 8.8

pHE Data 5.7e17 17409 3034.6

pHE MC 1.8e18 56799 3112.5 9.6


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Eν Distributions Now

LE10

MEHE

Black—DataRed—MCBlue—true NC

Scaled to POT

There’s still an offset…Difference in means:•LE10—1.9%•ME—5.8%•HE—4.5%


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Eμ Distributions Now

LE10

MEHE

Black—DataRed—MC

Scaled to POT

More low E muons in dataMore high E muons in MC


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Eshw Distributions Now

LE10

MEHE


Scaled to POT


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Lin. vs. Deweighted Eshw

LE10

MEHE


•Default Shower energy Is now the “deweighted” version•Reco E_nu looks better using this version of the shower energy!

Scaled to POT


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LE10

MEHE


But. . .There’s a problem with the deweighted shower energy

Scaled to POT

Differences between the two methods suggests an underlying data/MC difference


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Deweighted shw. energy bigger than linear shw. energy

Deweighted shw. energy smaller than linear shw. energy

DataMC

pME beam


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Track Strip Pulseheight

LE10

MEHE


Scaled to # Events


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Shower Strip Pulseheight

LE10

MEHE


Excess of <1PE hits in Data showers

1 PE ~= 100 sigcor

Scaled to # Events


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Shower strip times

LE10

ME HE


Scaled to # Events


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Shower Strip times

LE10

ME HE

Black—DataRed—MC For shower hits > 2.5 pe

Scaled to # Events


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Number of Shower Strips

LE10

ME HE


Scaled to # Events


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Number of Shower Strips

LE10

MEHE

Black—DataRed—MC For shower hits > 2.5 pe

Scaled to # Events

•Data and MC means agree within 1 strip•Mean in data > mean from MC•Few entries in the zero bin


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Ave Shower pulseheight

LE10

MEHE


Scaled to # Events


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Ave Shower pulseheight

LE10

MEHE

Black—DataRed—MC Only counting hits > 2.5 pe

Scaled to # Events

•Data and MC means differ by < 1pe•Data bigger than MC


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Max. Shower pulseheight

LE10

ME HE


Scaled to # Events

Few pe differences in meansData has bigger max shower pulse height than MC


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Total Shower pulseheight

LE10

MEHE


Scaled to # Events

•Data mean is bigger than MC mean•But in GeV, Data<MC?•Needs a closer look at sigcor->sigmap->mip conversion

X10^3

X10^3 X10^3


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Total Shower pulseheight

LE10

MEHE

Black—DataRed—MCOnly counting hits > 2.5 pe

Scaled to # Events

X10^3

X10^3 X10^3


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Clean Timing Cut

•Time between accepted event and the event closest in time•Designed to get rid of “runt events”•Used to cut out first bin (<50 ns)•Intensity dependent

LE10

MEHE


Scaled to POT


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Runt EventsT

ime

(ns)

Z (m)

Z (m)

Z (m)

Time (ns)

U (

m)

V (

m)

•Red—accepted event•Green—hits within 60 ns of event, in same slice but not in event•Pink—hits within 60 ns of event, but not in same slice•Blue—all hits from the slice that contains pink


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Event Timing

LE10

MEHE


Higher intensity in MC meansThe clean timing cut throws away many more good events in the MC than in data


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Event Timing

LE10

MEHE


Events in data last longer


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Event Timing

LE10

MEHE

Black—DataRed—MC Only considering hits > 2.5 pe


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Shower E vs. Duration

Reco. E shw (GeV)

Tim

e du

ratio

n (n

s)

LE10data

ME data

HEdata

MC

MC

MC

Lower energy showers last longer


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Cut on time duration

LE10

MEHE


Scaled to POT

There’s still an offset…Difference in means:•LE10—1.2%•ME—5.2%•HE—3.5%

Require time duration<200 ns


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Summary

•Bug found in Ely vintage MC. Old ME and HE spectra from MC do not have wfluk reweighting•New MC looks better, but there’s still an offset•Using deweighted shower energy calculation mitigates the shift, but is this masking an underlying difference?•Excess of <1 pe hits in showers•Other low level shower quantities don’t look crazy•Timing quantities differ between data and MC

•Time between events—different intensities•Time length of events

•Future investigations•Higher levels of calibration chain?•Different slicing parameters?

nd data/mc comparisons

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