Post on 08-Jan-2016
description
The DONUT Experiment: Fermilab E872
Aichi Univ. of Education K. Kodama,N. Ushida
Kobe University S. Aoki,T. Hara
Nagoya University N. Hashizume,K. Hoshino,H. Iinuma,K. Ito,
M. Kobayashi,M. Miyanishi,M. Komatsu,M. Nakamura,K. Nakajima,T. Nakano,K. Niwa,
N. Nonaka, K. Okada,T. Yamamori
Univ. of California/Davis P. Yager
Fermilab B.Baller,D.Boehnlein,W.Freeman,B.Lundberg,J.Morfin,R. Rameika
Kansas State Univ. P. Berghaus,M. Kubanstev,N.W. Reay,
R. Sidwell,N. Stanton,S. Yoshida
Univ. of Minnesota D. Ciampa,C. Erickson,K. Heller,R. Rusack,R. Schwienhorst, J. Sielaff,J. Trammell,J. Wilcox
Univ. of Pittsburgh T. Akdogan,V. Paolone
Univ. of South Carolina A. Kulik,C. Rosenfeld
Tufts University T. Kafka,W. Oliver, J. Schneps,T. Patzak
Univ. of Athens C. Andreopoulos,G. Tzanakos,N. Saoulidou
Gyeongsang University J.S. Song,I.G. Park,S.H. Chung
Kon-kuk University J.T. Rhee
DONUT Collaboration
E.Maher
FermilabE872
Moriond 2001
Jason Sielaff U. of Minnesota
The probability that all 4 events are from background sources is 410 -4
e
e ho
h
-
q´q
E872 has analyzed 203 neutrino interactions recorded in nuclear emulsion targets.
Four events are due to interactions.
The expected background is .3 events.
Observation of CC interactions
FermilabE872
Moriond 2001
Jason Sielaff U. of Minnesota
Production and detection of
C=.87mm
800GeV protons
Ds
BEAM DUMP
SHIELDING EMULSIONSTACK
SPECTROMETER
~1017 protons/ int. flux: ~107 @ 35cm~1012 @ 2m
+ N + X + 1 charge
FermilabE872
Moriond 2001
Jason Sielaff U. of Minnesota
Spectrometer
Muon ID
Calorimeter
Drift Chambers
Magnet (225Mev)
Emulsion andSci-Fi Planes
• trigger• muon ID• electron ID• momentum calibration•vertex location
5.5m
3.25m
Veto Wall (Double scintillator)
FermilabE872
Moriond 2001
Jason Sielaff U. of Minnesota
Emulsion Target
• AgBr suspended in a gel • 100 coated on plastic
base • Fuji ET7C • 29±2 grains per 100m
for m.i. Track• Total target mass 260kg
95% emulsion ~ 5% emulsion
Resolution of segmentsSpatial: .3 mAngular: 3mrad/100m
Segment detection efficiency : > 98%
BULK ECC800 ECC200
Fe
Fe
FermilabE872
Moriond 2001
Jason Sielaff U. of Minnesota
Emulsion Data Analysis
FermilabE872
Moriond 2001
Jason Sielaff U. of Minnesota
203 systematic decay search
6.6106 triggers
Data set
Phase 1 data set of 203 interactions:
Expect Find
e 71 cc 61 e cc
901 predicted vertices from spectrometer (consistent w/ 3.6x1017 POT)
699 within fiducial volume
511 digitized emulsion data exists
264 vertex foundPhase 2 as of Feb 2001
+ 95
+ 28
FermilabE872
Moriond 2001
Jason Sielaff U. of Minnesota
interaction selection
Cuts: Parent track 1 visible segment kink > 10 mrad (mr)
Decay length < 5 mm (2.3 mm)Transverse Momentum > 250 MeV IP of daughter to interaction vertex < .5 mm Total
acceptance = .50
track
Expected number of (data set of 203) 41
Single charge decay accounts for 86% of all decay modes.These result in a kink in the reconstructed emulsion track
Only events with no or e identified from interaction vertex
FermilabE872
Moriond 2001
Jason Sielaff U. of Minnesota
Background sources I
7.9 m of primary tracks scanned
Using LEPTO/GEANT simulation
passing cuts .10 kinks /203evts.
NC, e or lost
Random: association of background track with a primary track
Hadronic interactions
NC, e or lost
h
Density of background tracks starting Stopping primary tracks N primary Probability of match with SFT PSFTmatch
N rndn = startingr2match N primary. PSFT match
rmatch = 5 (5) passing t cut .017kinks/203evts.
FermilabE872
Moriond 2001
Jason Sielaff U. of Minnesota
Background sources II : charm
Total & e 155 ±18
0.47±0.05 5.72±1.0 Charged 6.46 ±1.1 Neutral
0.38±0.02 2.2 ±.4 single chargedecay
cc in sample
0.077±0.007 12.1±1.8 Charm production
recognized
.18 ± .03 e or not
& pass cuts
e or : not recognized
e cccharm
Displaced vtx: example of neutral charm
FermilabE872
Moriond 2001
Jason Sielaff U. of Minnesota
Event 3024_30175
e +
Decay occurs in plastic base
Event 3263_
h
Decay occurs in steel plate
FermilabE872
Moriond 2001
Jason Sielaff U. of Minnesota
Event 3333_17665
e +
Decay occurs in plastic base
Event 3039_01910
h
Decay occurs in plastic base
FermilabE872
Moriond 2001
Jason Sielaff U. of Minnesota
Individual event parameters
prim production angle of L d decay lengthPT transverse
momentum of the decay
event angular symmetry
prim
L dPT
Parameters used to characterize event:
prim
Distributions of event parameters:
interactions
FermilabE872
Moriond 2001
Jason Sielaff U. of Minnesota
vs. background hypotheses
The probability of an event with measured parameters belonging to a given hypothesis is determined using multi-dimensional PDF. The PDF’s are generated with simulated events of each hypothesis.
)|(
)|(|
ipgA
pgApP
i
p
i = , hadron interaction or charm
Ai prior probability of hypothesis)|( ipg
probability density function
.88 .97 .13 .98
charm .12 .03 .01 .02
had. int. NC 0<.001
.51 0
had. int. e CC
0<.001
.15 0
had. int. m CC
0<.001
.02 0
30
24
-3
01
75
30
39
-0
19
10
32
63
-2
51
02
33
33
-1
76
65
Probability all events are background = 8.0 10-5
FermilabE872
Moriond 2001
Jason Sielaff U. of Minnesota
Status
Results of “Long” decay search : (Physics Letters B )
Measurement of magnetic moment : (Physics Letters B )
Upper limit 4.27 10-7 B
PHASE 2 of analysis (in progress)
Data set of located interactions increasing +95 Feb. 2001Goal of 400 total by summer 2001
“Short” decay search to be completed : expect ~ 1 interaction
Relax cuts for decay search