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