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A Direct Search for Magnetic Monopoles at H1
HEP03, Aachen, 17-23/7/03
David Milstead The University of Liverpool
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Monopoles in Particle Physics
‘t hooft/Polyakov – Monopole from breaking of simple symmetry group into U(1)SUSY GUTs: 1015 GeV Little Higgs: 1-5 TeV ?
Electric charge quantisation Dirac - e=nh/g
Gauge group symmetry breaking
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First search in ep at =300 GeV
Sensitive to 150 GeV mass
QED coupling for Dirac Monopole gD
g=gD2/434
em=1/137
Monopoles at HERA
p
s
Processes predicted but not rate
103 greater ionisation energy loss rate than mip
m
m
e e’
g
em
g
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Monopoles of strength > 0.75 gD stoppedBind to Al nucleus dipole moment and only released by melting (Milton et al.)Take 60cm section of 2mm thick H1 beam-pipe around interaction zone.Used 1994-1997 : lumi=60pb-1
Cut into 14 strips and pass through superconducting loops and measure current.
Monopoles in the H1 beam pipe
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Southampton SQUID
• DC SQUID (2G mod. 581) at Southampton Oceanography Centre, UK.
• Sample sizes up to 1m long and 5cm radius.
• Measures changes in magnetic field 10-12 T.
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90gD
10gD
1.2gD
Ind
uce
d c
urr
en
t
x 10
-1x
10-2
position /cm
CalibrationSignature of monopole is persistent current
Use solenoids with varying currents to
mimick step
solenoidsc loop
i
B
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Signal survival Monopole signal survives after strip
traversal
strip
Solenoid ( = 1 gd)i
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Beam pipe measurements Induced current from strips
No candidates found
Dirac Monopole
Strip number
Cur
rent
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Monopole Acceptance
Rising acceptance with high charge and low mass
Use mm (comphep) model
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Cross-section upper limits
First upper limits in ep collisions
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Upper limit for Dirac Monopole Production
Different experimental techniquesCompetitive ep limit
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Upper limit for 3gd monopoles
Only limits from ep and pp
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First search in electron-proton scattering at =300 GeV at the H1 experiment
Search for monopoles stopped in the beam pipe.
Monopole masses up to 150 GeV and charges 1 < gD < 6 excluded.
Magnetic monopoles play fundamental role in modern physics theories.
Summary and Outlook
s