The KEKB injector linac

Rehman

Miyahara

2021

Sci Rep

The direct simultaneous detection of electron and positron bunch signals was successfully performed for the first time with wideband pickups and a detection system at the positron capture section of the SuperKEKB factory. The time interval between the electron and positron bunches, their bunch lengths, and bunch intensities depending on the phase of accelerating structures were measured to investigate their capture process and to maximally optimize the positron intensity. The results show that the time intervals were measured in the range of 135–265 ps, and the line-order switch of the electron and positron bunches in the axial direction was clearly observed as a function of the phase. The positron (electron) intensity was maximized at the optimal phase (180$$^{\circ }$$ ∘ shifted from the optimum). These series of measurements have never been experimentally conducted so far. It is demonstrated that the positron intensity can be systematically optimized with this system as functions of beam parameters in multidimensional spaces for any positron capture section.

Section: Methodsmentioning

confidence: 99%

“…The SKEKB injector linac 7 is an linear accelerator for the SKEKB; the KEKB injector linac 8 was upgraded for the abovementioned purpose. The requirements for the injector linac are full energy injection into the SKEKB rings with the and bunch charges of 5 and 4 nC, respectively.…”

Section: Introductionmentioning

confidence: 99%

First simultaneous detection of electron and positron bunches at the positron capture section of the SuperKEKB factory

Rehman

Miyahara

2021

Sci Rep

“…Here, we briefly describe the components and operation scheme for the laser-based alignment system of the injector linac. Figure 1 shows a schematic layout of the KEKB injector linac [16]. It comprises eight sectors (A-C and 1-5), which together constitute two long straight sections.…”

Section: A Layout Of the Beam Linementioning

confidence: 99%

Real-time observation of dynamic floor motion of the KEKB injector linac with a laser-based alignment system

Phys. Rev. Accel. Beams

Enomoto

Kakihara

et al. 2017

Self Cite

A new remote-controllable sensing system for a laser-based alignment system is in development to measure slow dynamic displacements of the tunnel floor in real time at the KEKB injector linac. Although the injector linac had initially been aligned with a laser-based alignment system, we have found that, based on recent real-time observations, the transverse displacements of the tunnel floor to the laser axis caused by dynamic ground motion are not negligibly small compared with the required alignment tolerance, in terms of the straightness of the beam line. Based on spatial and temporal cross-correlation analyses performed using displacement vectors from data recorded during a nearly eight-month period, it was found that the tunnel floor moves coherently in space and time domains over the entire length of the linac on average over long periods of time, while the cross-correlation function varies irregularly and complexly over shorter periods of time. This report describes in detail the basic design, experimental results, and present status of the new remote-sensing system for real-time alignment observations at the KEKB injector linac.

“…The SKEKB injector linac 7 is an e − /e + linear accelerator for the SKEKB; the KEKB injector linac 8 was upgraded for the abovementioned purpose. The requirements for the injector linac are full energy injection into the SKEKB rings with the e − and e + bunch charges of 5 and 4 nC, respectively.…”

Section: Introductionmentioning

confidence: 99%

First Simultaneous Detection of Electron and Positron Bunches at the Positron Capture Section of the SuperKEKB Factory

Rehman

Miyahara

2021

Preprint

The direct simultaneous detection of electron and positron bunch signals was successfully performed for the first time with wideband pickups and a detection system at the positron capture section of the SuperKEKB factory. The time interval between the electron and positron bunches, their bunch lengths, and bunch intensities depending on the phase of accelerating structures were measured to investigate their capture process and to maximally optimize the positron intensity. The results show that the time intervals were measured in the range of 135–265 ps, and the line-order switch of the electron and positron bunches in the axial direction was clearly observed as a function of the phase. The positron (electron) intensity was maximized at the optimal phase (180 deg shifted from the optimum). These series of measurements have never been experimentally conducted so far. It is demonstrated that the positron intensity can be systematically optimized with this system as functions of beam parameters in multidimensional spaces for any positron capture section.