1ICHEP 2000, OsakaAugust 2000
-N Differential cross-sections
Structure functions
and
Measurement of
using the
CHORUS lead calorimeter at CERN
Rolf Oldeman (NIKHEF, Amsterdam) for the CHORUS collaboration
2
Experimental setup
450 GeVprotons(SPS)
WANF neutrino beamline CHORUSdetector
300 m decay tunnel
focussing magnets
beryllium target
lead/scintillating fiber calorimeter-target
magnetized ironmuon spectrometer
,K
3
A typical event
%1712
p
)p(
mrad220160
p
)(
hadhad E)E(
%6040
hadNBj EM
Qx
2
2
212 4 2sinpEQ
hadEpE
Kinematic variables:
Detector resolution:
E/Ey had
4
CHORUS 1998 DIS data
Triggered & selected:
Applied cuts: fiducial volume: 15.1 tonright sign muon (contamination:2%, 32%)p> 4 GeV< 300 mradEhad < 100 GeV10 < E< 200 GeV
After cuts:
beam beam
3638k
1125k
1032k
234k
5
Differential -N cross-sections
binning in (E,x,y): 10<E<200GeV 10 bins0.01<x<0.7 11 bins0.05<y<0.95 9 bins
yx)E(N
)y,x,E(N
Edxdyd
E1 ,
tot2
Ehad scale
Ehad offset
p scale
p offset
5%150 MeV2.5%150 MeV
2.1%1.4%
1%/100GeV0.5%/100GeV
systematic uncertainties:
Dominant!
use:
total N
total N /N
N(E)N /N(E)
6
ExampleE=55 GeVxbj=0.275
0 1y
cross-section results
0.5
1.0
1.5
Numerical tables atchoruswww.cern.ch/~oldeman
First high statistics Ndata on a lead target!
(10-3
8 cm
2 GeV
-1)
7
Binning E,x,yto x,Q2,y
Radiative corrections(Bardin)
Isoscalarity correction
Structure functionextraction
8Extracting 6 structure functions
Very strong correlations.Especially 2xF1,xF3
Large statistical errors
Need large range in y limited # of x,Q2 bins satisfy
3
221
2N
12
21
22W
2
N2F
2
xFyyFE2
xyMy1xF2y
MQ1
EMG
dxdyd
9
Assume:
)cs(4xFxF
FF
xF2xF2
33
22
11
Reasonable correlations
10x smaller statistical error
measure R(x,Q2):
1xF2
F
Q
xM41R
1
22
22N
Extracting 3 structure functions
10
Results on R
(x,Q2)
SLA
C R
1990
11‘Classical’ 2-structure function extraction
Use R(x,Q2) = SLAC R1990 (20%)
Reduced statistical error
Small correlation
12M
easured structure functions F
2 (x,Q2) and xF
3 (x,Q2)
LO m
odel
13Com
parison with C
CF
R and C
DH
SW
F2 (x,Q
2)Consistent w
ith CC
FR
Inconsistent with C
DH
SW
14Com
parison with C
CF
R and C
DH
SW
xF3 (x,Q
2)
Mostly consistent
(except high-x)
15Conclusions
First high statistics neutrino data on a lead target
Differential cross-section measured
Structure functions F2(x,Q2), xF3(x,Q2) and R(x,Q2)measured
Consistent with CCFR, discrepancy with CDHSW