Bunch-length and beam-timing monitors in the SLC final focus

Abstract

During the 1997 98 luminosity run of the Stanford Linear Collider SLC, two n o v el RF-based detectors were brought i n to operation, in order to monitor the interaction-point IP bunch lengths and uctuations in the relative arrival time of the two colliding beams. Both bunch length and timing can strongly a ect the SLC luminosity and had not been monitored in previous years. The two new detectors utilize a broad-band microwave signal, which i s excited by the beam through a ceramic gap in the nal-focus beam pipe and transported outside of the beamline vault by a 160-ft long X-Band waveguide. We describe the estimated luminosity reduction due to bunch-length drift and IP timing uctuation, the monitor layout, the expected responses and signal levels, calibration measurements, and beam observations.

Study of the beam dynamics in a linac with the code retar

“…As a consequence the tail, in drift region, assumes the characteristic exponential decay of a wake field [7]. Another possible use of retarded fields measured in a point like spot, is the determination of the bunch length [5] and its longitudinal charge profile. In Figure 4 the time signal for the electric field, taken in a point placed at z = 10 mm and r = 5 mm, is plotted for different bunch lengths, going from 2 up tp 20 ps.…”

“…A solenoid field is located after the RF gun to perform the emittance compensation scheme [2,3] and the overall configuration of external fields is the same improved in the SPARC project [4]. We focus our study on the amount and temporal profile of the radiation emitted in the acceleration and focusing process in order to asses its possible exploiting for a non destructive diagnostic of the beam [5].…”

Ultimate gradient in solid-state accelerators

“…Monitoring of bunch lengths below 30 µm will require manipulation of THz frequencies. Where the final focus employs β µ * ≈150 m, monitoring of beam-timing in collision will require phase-measurements accurate to a few degrees at W-Band, without averaging (82). With normalized beam emittance of ε nx,y ≈ 10 -7 m-rad, maximum beam-size at the exit of a 2.5 TeV machine is σ x,y ≈ 0 6…”

Introduction to Microwave Linear [Accelerators]

“…According to our analysis of the eect of a single-coupling iris, as summarized in Eqs. (43) and (44), we expect that cell voltages in the innite structure will satisfy…”