Abstract:T-474 at SLAC is a prototype BPM-based energy spectrometer for the ILC. We describe magnetic measurements and simulations for the 4-magnet chicane used in T-474.
The International Linear Collider (ILC) and other proposed high energy e + e − machines aim to measure with unprecedented precision Standard Model quantities and new, not yet discovered phenomena. One of the main requirements for achieving this goal is a measurement of the incident beam energy with an uncertainty close to 10 −4 . This article presents the analysis of data from a prototype energy spectrometer commissioned in 2006-2007 in SLAC's End Station A beamline. The prototype was a 4-magnet chicane equipped with beam position monitors measuring small changes of the beam orbit through the chicane at different beam energies. A single bunch energy resolution close to 5 · 10 −4 was measured, which is satisfactory for most scenarios. We also report on the operational experience with the chicane-based spectrometer and suggest ways of improving its performance.
The International Linear Collider (ILC) and other proposed high energy e + e − machines aim to measure with unprecedented precision Standard Model quantities and new, not yet discovered phenomena. One of the main requirements for achieving this goal is a measurement of the incident beam energy with an uncertainty close to 10 −4 . This article presents the analysis of data from a prototype energy spectrometer commissioned in 2006-2007 in SLAC's End Station A beamline. The prototype was a 4-magnet chicane equipped with beam position monitors measuring small changes of the beam orbit through the chicane at different beam energies. A single bunch energy resolution close to 5 · 10 −4 was measured, which is satisfactory for most scenarios. We also report on the operational experience with the chicane-based spectrometer and suggest ways of improving its performance.
“…Measured and calculated mid-chicane beam de ection at energy scan A prototype spectrometer chicane employing four-dipole magnet is currently under development at SLAC [12]. The ILC energy measurement technique was tested in the JINRÄ SLACÄDESY joint research at T-474 project to demonstrate performance of the spectrometer with a 28.5-GeV beam [12,13]. The comparison of the experimentally measured and simulated values of bunch de ection in the mid-chicane region during 5 steps of energy scan in the range ±0.2 GeV is given in Fig.…”
Different methods for diagnostics of ultrashort electron bunches are developed at JINRÄDESY collaboration within the framework of the FLASH and XFEL projects and JINR participation in the ILC project. The main peculiarity of these accelerator complexes is related to formation of ultrashort electron bunches with r.m.s. length 20Ä300 μm. Novel diagnostics is required to provide femtoscale time resolution in the modern FEL like FLASH and future XFEL and ILC projects. Photon diagnostics developed at JINRÄDESY collaboration for ultrashort bunches is based on calorimetric measurements and detection of undulator radiation. The MCP-based radiation detectors are effectively used at FLASH for pulse energy measurements. The infrared undulator constructed at JINR and installed at FLASH is used for longitudinal bunch shape measurements and for two-color lasing provided by the FIR and VUV undulators. Two-color lasing in pump-probe experiments permits one to investigate dynamics of atomic and molecular systems with time resolution of 100Ä500 fs. A special magnetic spectrometer is planning to be used at ILC for measurements of average electron energy in each bunch. Thě rst test spectrometer measurements were performed within the JINRÄDESYÄSLAC collaboration. A special synchrotron radiation detector applied for measurement of bunch average electron energy was constructed at JINR.
“…To define beam deflection range in the middle of the chicane (region of the BPM4) [3] the beam (with SLAC Linac parameters) tracking was carried out taking into account measured in SLAC Test Lab dipoles magnetic field (current equals 150A) (see Fig. 3).…”
Section: Preliminary Tracking To Define Beam Deflection Rangementioning
confidence: 99%
“…The magnetic field map of dipoles was normalized such a way that Bdl-integral which beam "sees" when tracking through each magnet equals real magnetic field integral values which were obtained by control probes data [3]. Energy of the tracking particles equals measured bunches energy [3] in first part of the run-1699 during energy scan -200 → +200 MeV in five steps from nominal value.…”
Section: Beam Tracking Using Measured Energy Datamentioning
confidence: 99%
“…Energy of the tracking particles equals measured bunches energy [3] in first part of the run-1699 during energy scan -200 → +200 MeV in five steps from nominal value.…”
Section: Beam Tracking Using Measured Energy Datamentioning
T-474 at SLAC is a prototype BPM-based energy spectrometer for the ILC. A 4-dipole chicane is used with mid-chicane dispersion of 5-mm and magnetic fields of ~1 kGauss; these match the current ILC parameters. Better than 100 part-per-million (ppm) accuracy is needed for ILC energy measurements, requiring better than 50 ppm accuracy for magnetic field integral measurements.Code for beam tracking through the spectrometer chicane was developed. Magnetic field maps for dipole magnets obtained from the measurements at SLAC are used. Different aspects of the magnetic field influence to the beam deflection value are discussed. Results of the beam dynamics study using the measured magnetic fields for T-474 chicane to estimate magnetic effects on capabilities for the energy measurements are also reported.
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