R-ECFA, Prague, March 9, 2007

J. Žáček 1

Czech participation in the H1 experimentJ. Žáček,

Institute of Particle and Nuclear Physics, Charles University in Prague

•Institute of Physics of the Academy of Sciencies of the Czech Republic•Institute of Particle and Nuclear Physics, Faculty of Mathematics and Physics, Charles University in Prague

Participation since 1987: subdetector construction design and production of electronics program development data analysis H1 Prague group : 5 senior physicists, 4 PhD students

Financial support : Ministry of Education, Youth and Sports running costs , visits at DESY and conferences

R-ECFA, Prague, March 9, 2007

J. Žáček 2

H1 experiment

e

p

Prague contribution:

Calorimeter SPACAL (1994-1995)

Liquid argonCalorimeter(1987-1990)

Backward silicon tracker(1996-1997)

Forward silicon tracker(2001-2005)

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Prague contribution to the Forward silicon tracker (FST)

• Testing of silicon sensors (laser tests etc. .. }• Development and production of electronics• Development of the slow control and DAQ• Simulation of FST• Analysis of data taken in 2004 ( D* production)

FST was constructed mainly by DESY-Zeuthen and PragueThe first FST data were taken in 2004

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Forward and backward silicon detectors

e

p

FST

BST

electronics cards

electronics cards (repeaters)

wheels of stripSi sensors

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Si sensor wheels

repeaters

converters

Converters + repeaters were designed and produced in Prague

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Converter card: power supply and control circuits for 8 data channels

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Reconstructed event

longitudinal view

transverse view

FST wheels

Track reconstruction in FST

FST track residuals

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J. Žáček 9

Very Forward proton spectrometer (VFPS)

Installed in 2003. Detection of diffracted protons scattered in the beam pipe

3.7 m

IP

t < 0.25 GeV2

VFPS, 220 m

H1

p

e

VFPS2 VFPS1

Beam pipe

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VFPSCzech participation: Reconstruction of tracks in VFPS (in collaboration with Belgian H1 group)A method based on the neural network was developedGoal: From hits in the VFPS to get proton track parameters in the interaction vertex. This is a complicated procedure since there are accelerator magnets which have influence on proton tracks.

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Data analysis

Measurement of dijet production at low Q2 at HERA

e + p e + X

Q2 = - (k – k’ )2 , y =

jet

undetected jet

Pp q

Pp k

pp

e

eDirect photoninteractions

p

e

Resolved photoninteractions

Q2

LO

NLO

LO

LO NLO

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Measurement of dijet production at low Q2 at HERA

DATA 99/00, 2 < Q2 < 80 GeV2

GOAL : Detailed comparison of triple differential cross sections (e.g. d3 / dQ2dy d* , jet rapidity in -p CMS) with generators and NLO QCD calculations

Generators : HERWIG,LO MC, DGLAP evolution, dir + res photons

+ parton showering + cluster hadronisation CASCADE,LO MC, unintegrated PDF+ CCFM evolution scheme + LUND string hadronisation

NLO calculations: JETVIP

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Measurement of dijet production at low Q2 at HERA

● H1 data

HERWIG dir

HERWIG dir+resT

HERWIG dir+resT

+resL

CASCADE

NLO JTEVIP dir

NLO JTEVIP total

0.1 < y < 0.25 0.25 < y < 0.5 0.5 < y < 0.85

*-2 -1 0 -2 -1 0 -2 -1

QCD calculations

Generators

• NLO QCD calculations underestimate data at high y• HERWIG – better agreement if the longitudinal photon is included

(pb)

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Dijets in difractive photoproduction

DATA 99/00 , Q2 < 0.1 GeV2 ( photoproduction) , t < 1 GeV2

• Test of QCD factorisation in dijet diffractive photoproduction

• Comparison of data with NLO calculations

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J. Žáček 15

Dijets in difractive photoproduction

Motivation: Dijet diffractive cross section determined at TEVATRON is lower by a factor ~ 5 than the QCD calculation using HERA diffractive PDFs.

Exporting HERA PDFs to the Tevatron doesn’t work ?, factorisation breaking?

Analogy of pp interactions and ep resolved photon interactionsH1 data analysis is performed by our PhD student

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Further activities and outlook

• Calibration of the VFPS with mesons , data 2005/2007

• Calibration of final state hadronic energies

• Development of the software package HZTOOL, which enables fast comparison of theoretical calculations with published experimental results

Further activities:

Outlook: ~ next 4 years analysis of H1 data from 05-07 (~ 3 PhD thesis) - measurement of the longitudinal diffractive proton structure function - forward jets in diffraction