Download
1 / 34
340 likes | 487 Vues
Current Performance and Future Possibilities of HERA. 7 July 2001 Georg Hoffstaetter (DESY, Hamburg). HERMES (7 GeV). H1 (318 GeV). HERA. ZEUS. HERA-B (42 GeV). PETRA. H1. 778 m. HERMES. HERA. HERA-B. Polarized Electrons Protons. DESY. PETRA. ZEUS. 6336 m long.
E N D
Current Performanceand Future Possibilities of HERA 7 July 2001 Georg Hoffstaetter (DESY, Hamburg) HERMES (7 GeV) H1 (318 GeV) HERA ZEUS HERA-B (42 GeV) PETRA
H1 778 m HERMES HERA HERA-B Polarized Electrons Protons DESY PETRA ZEUS 6336 m long HERA and its Pre-Accelerator Chain Georg.Hoffstaetter@desy.de
HERA: Improvements 1999/2000 Beam current: and 1999 2000 mA Average peak luminosity ( ) 1999 2000 Georg.Hoffstaetter@DESY.de
1999 2000 HERA: Efficiency 1999/2000 Georg.Hoffstaetter@DESY.de
Development of the Luminosity HERA Luminosity 1993-2000 Linear increase of the integrated Luminosity Integrated Luminosity (1/pb) The time for a luminosity upgrade of HERA has come Days after start of run Georg.Hoffstaetter@DESY.de
specific luminosity ( ) Specific Luminosity and Polarization % 55 Georg.Hoffstaetter@DESY.de
The HERA Lumi-Upgrade Georg.Hoffstaetter@DESY.de
Concept of HERA IRs m • Beam separation by super-conducting magnets in the detectors • e-bending radius reduced from 1200 m to 400 m • More radiation power: 28 kW, critical Energy = 150 kV • Radiation passes the detector, absorbers at 11, 19, and 25 m Georg.Hoffstaetter@DESY.de
The Detector Region courtesy B.Holzer courtesy B.Holzer Georg.Hoffstaetter@DESY.de
New Components • 4 super-conducting magnets ( BNL ) [6 MDM] • 56 normal-conducting magnets (Eframov Inst.) [6 MDM] • 448 m UH Vacuum system [6 MDM] • Absorbers, instrumentation, controls, stands, … [6 MDM] Georg.Hoffstaetter@DESY.de
Superconducting Magnet GO Georg.Hoffstaetter@DESY.de
Superconducting Magnet GO Georg.Hoffstaetter@DESY.de
One Pipe - Three Beams Georg.Hoffstaetter@DESY.de
Synchrotron Radiation Absorber Georg.Hoffstaetter@DESY.de
Parameters Georg.Hoffstaetter@DESY.de
Potential Problems Focusing: • Dynamic Aperture OK? • Polarization OK?, Luminosity OK? • Can HERA be handled well? • Polarization OK?, Luminosity OK? • Too strong beam-beam force on p? • Too strong beam-beam force on e? fRF increase: Georg.Hoffstaetter@DESY.de
Emittance and Lumi for 72° Optic • The Luminosity was initially too small: Lumiscan Bunch has no product distribution: • coupling • Luminosity with 72° is large as expected Georg.Hoffstaetter@DESY.de
Kick Dynamic Aperture for 72° Optic x´ V2(kV) The kick where half the current is lost leads to a satisfactory dynamic aperture. x Georg.Hoffstaetter@DESY.de
Polarization Ie 60% Polarization for 72° Optic • Polarization was in the spin matched 72° optic quickly brought to 63% (one day). • Harmonic bumps were immediately effective • Decoupling bumps worked well Georg.Hoffstaetter@DESY.de
Luminosity for fRF Increase • 6 more measurements indicate • For the center frequency , the luminosity is increased as expected Georg.Hoffstaetter@DESY.de
Too Strong Beam-Beam Force on p? 16mA 73mA Corresponding e-current after upgrade Lsis independent of e-current Tp depends on e-current Tails depend on e-current Georg.Hoffstaetter@DESY.de
Too Strong Beam-Beam Force on e? Ls So far no reduction of Ls by the bunch current Ippb No reduction of Ls by the second experiment No reduction of Ls by a larger b-funktionen Georg.Hoffstaetter@DESY.de
Limits for the Lumi Upgrade m • beam-beam tune shiftfor e and p • hourglass effectfor protons • backgrounddue to synchrotron radiation and scattered e • dynamic apertureof electrons Georg.Hoffstaetter@DESY.de
Where are the Beam-Beam Limits? Upgrade and Ip=140mA: emittance starts to grow Georg.Hoffstaetter@DESY.de
Luminosity ( ) Lumi Reduction by Hourglass Effect bunch length: 6cm p e 20cm 30cm Length19cm: 12cm: Georg.Hoffstaetter@DESY.de
mm mm m Horizontal: grows slower Vertical: grows faster Tuneshift Change by Hourglass Effect Protons Electrons Georg.Hoffstaetter@DESY.de
Tune Shift with Bunch Length Effect How will the tune shift parameters change and have these been analyzed by accelerator experiments ? Georg.Hoffstaetter@DESY.de
Bunch Length Dependent Resonances 10Qy Resonance 6Qx+4Qy Resonance For maximum For maximum Georg.Hoffstaetter@DESY.de
Resonances with Bunch Length Effect How will the resonance strength change and have these been analyzed by accelerator experiments ? All large resonance strength are due to the proton bunch length Georg.Hoffstaetter@DESY.de
Nominal and Ultimate Parameters The performance goal of HERA is not unrealistic and should not be too hard to achieve. A shortfall of beam intensity in the short term can be compensated. Georg.Hoffstaetter@DESY.de
Spin-Orbit Tracking with Quaternions • Computation of the • invariant spin field by analyzing tracking data: • Fourier analysis • Stroboscopic averaging • Antidamping Computations performed in SPRINT, Hoffstaetter and Vogt, DESY/00 Georg.Hoffstaetter@DESY.de
High Order Resonance Strength • Resonances up to 19th order can be observed • Resonance strength can be determined from tune jump. Spin tune Tracked depolarizationasexpected Computations performed in SPRINT, Hoffstaetter and Vogt, DESY/00 Georg.Hoffstaetter@DESY.de
Increasing the Proton Current PETRA: N=60, 50 MHz 10 MHz & 5 MHz N=30, 50 MHz 10 MHz & 5 MHz Georg.Hoffstaetter@DESY.de
TESLA with Röntgen FEL Röntgen FEL Super-conducting Electron Linac Detector and Experimental Area Wiggler for the Positron Source Cryogenic Halls Super-conducting Positron Linac Tunnel Damping Ring Georg.Hoffstaetter@DESY.de
