Proposal to Modify the Polarimeter Chicane in the ILC 14 mrad Extraction Line

Abstract

A proposal is presented in this paper to modify the extraction line polarimeter chicane to allow the Compton backscattered electrons to be deflected further from the beam line, and to provide optics for the downstream GAMCAL detector. IntroductionThe current version of the extraction line polarimeter chicane as shown in figure 1 has four magnets located between z = 120 to 175 m [1]. We propose to run the last two polarimeter magnets BVEX3P and BVEX4P at 1½ the B-field of the first two magnets BVEX1P and BVEX2P. With the higher field the Compton electrons are deflected further away from the beam line allowing the Cherenkov detector to cover a larger range of the Compton scattered spectrum. Two additional magnets downstream of the polarimeter chicane close the orbit of the extracted beam for transport to the dump. These magnets will be used by the Gamma Calorimeter (GAMCAL) detector [2].

The International Linear Collider Technical Design Report - Volume 3.II: Accelerator Baseline Design

“…In the high background environment of the disrupted beam, the required high laser power allows measurement of only a few bunches out of each train. The chicane of the downstream polarimeter consists of six vertical bends to maximise the analysing power and to deflect the Compton-scattered electrons out of the synchrotron-radiation fan [187].…”

“…The klystrons and modulators are installed on the surface in 22 groups or 'clusters' (11 per linac). Each cluster contains 18 or 19 klystrons, the combined RF power of which (180)(181)(182)(183)(184)(185)(186)(187)(188)(189)(190) is transported via a large 0.48 m-diameter overmoded cylindrical waveguide, first down a vertical shaft into the accelerator tunnel, and then along approximately 1 km of linac, where it drives ∼600 cavities ( Fig. 3.44).…”

Evaluation and compensation of detector solenoid effects on disrupted beam in the ILC 14mrad extraction line

“…2), a four bend vertical chicane for polarization measurement, and two vertical bends for gamma calorimeter luminosity diagnostics (Fig. 3) [8]. The polarimeter bends create 2 cm vertical dispersion at the Compton IP located at center of the polarimeter chicane.…”

Polarimeters and Energy Spectrometers for the ILC Beam Delivery System

“…[9] The downstream polarimeter chicane successfully accommodates a detector for the downstream energy spectrometer and provides magnetic elements for the GAMCAL system. [9] Figure 7: Schematic of the ILC extraction line diagnostics for the energy spectrometer and the Compton polarimeter.…”