| Paper | Title | Page |
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| MOPLS054 | On Increasing the HERA Luminosity | 667 |
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| The luminosity of the HERA lepton proton collider is limited in part by the bunch length of the protons of 20cm. This limitation is expected to be removed by the installation of a new damper system which will control longitudinal coupled bunch instabilities of the proton beam and avoid the bunch lengthening of a factor of two. This opens the possibility for increasing the luminosity HERA since the beta functions at IP for both leptons and protons can be lowered by about 20% without noticeable reduction of the corresponding luminosity by the so-called hour-glass effect. The beam spot size can be further reduced if the beam-beam focusing of the leptons (dynamic beta) at IP is increased by softening the rigorous beam beam-beta beat compensation which is accomplished by proper phasing of the two IP's. Unfortunately the non-linear chromaticity compensation would be weakened as well, which will cause an enhancement of the synchro-betatron resonances and may lead to poor lifetime and poor background conditions. Therefore, the non-linear chromaticity needs to be reduced by means of a more complex scheme of chromaticity compensating sextupole magnets. | ||
| MOPLS055 | A Lepton-proton Collider with LHC | 670 |
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The physics, and a design, of a Large Hadron Electron Collider (LHeC) are sketched. With high luminosity, 1033cm-2s-1, and high energy, ?s = 1.4TeV, such a collider can be built in which a 70GeV electron (positron) beam in the LHC tunnel is in collision with one of the LHC hadron beams and which operates simultaneously with the LHC. The LHeC makes possible deep-inelastic lepton-hadron (ep, eD and eA) scattering for momentum transfers Q2 beyond 106GeV2 and for Bjorken x down to the 10-6. New sensitivity to the existence of new states of matter, primarily in the lepton-quark sector and in dense partonic systems, is achieved. The precision possible with an electron-hadron experiment brings in addition crucial accuracy in the determination of hadron structure, as described in Quantum Chromodynamics, and of parton dynamics at the TeV energy scale. The LHeC thus complements the proton-proton and ion programmes, adds substantial new discovery potential to them, and is important for a full understanding of physics in the LHC energy range.
Contributed to the Open Symposium on European Strategy for Particle Physics Research, LAL Orsay, France, January 30th to February 1st , 2006. hep-ex/0603016 DESY 06-00Cockcroft-06-05 |
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| TUPCH023 | Direct Observation of Beam-beam Induced Dynamical Beta Beating at HERA | 1046 |
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| The Hadron Electron Ring Anlage (HERA) at DESY provides collisions between a 920 GeV proton beam and a 27.5 GeV electron beam in two interaction regions. The strong beam-beam force, which mainly affects the electrons, induces a tune shift together with a dynamical beta beat. The latter leads to a modification of the transverse beam profile, which can be observed in different profile monitors in HERA. The time-like evolution of the electron beam shape during luminosity tuning and before and after dump of the proton beam, averaged over all bunches, could be studied by means of a synchrotron radiation profile monitor. Measurements with a wire scanner allowed to see the beam-beam force's influence on each individual bunch at the expense of resolution. The observations could be explained qualitatively in the frame of linear incoherent beam-beam interaction. | ||
| THPCH083 | A Tune Feedback System for the HERA Proton Storge Ring | 2979 |
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| The transverse tunes of an accelerator or storage ring are important parameters which have to be controlled and adjusted continuously during beam operation in order to assure good experimental background conditions. For the HERA proton storage ring, persistent current effects of the superconducting magnets are the main source for the inadequate repeatability of the tunes without a feedback while the proton beam is accelerated. A tune feedback has been developed, implemented and tested during beam acceleration and luminosity operation. Considering the different conditions during energy ramps and luminosity runs two versions of this feedback system have been established based on different correction and peak-finding algorithms (e.g. wavelet analysis). No additional excitation is needed on top of the standard tune indication system in HERA. The tunes could be kept constant during beam accceleration with a standard deviation of delta Q = 0.003. In luminosity runs where the tune control is more critical, first tests resulted in a standard deviation which was a factor of ten smaller. The feedback system is implemented as a standard tool for beam acceleration. | ||
| FRXBPA01 | HERA and the Next Generation of Lepton-ion Colliders | 3621 |
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| This talk will present a summary of the physics insights gained from the lepton-hadron collider HERA and review major beam dynamics issues and lessons learned in view of LHC operation, including technical aspects related to the large number of superconducting magnets or the influence of various design choices on the overall machine performance. It will also address future plans for lepton-ion colliders, including eRHIC at BNL and the CEBAF-based ELIC, with emphasis on their luminosity reach and challenges. The talk will also mention possible high energy lepton-ion collisions, for example colliding a 1 TeV proton (or ion) beam from the Tevatron or Super-SPS with a 20-75 GeV electron beam from the ILC or CLIC (first stage). | ||
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