Scientific opportunies for bERLinPro 2020+, report with ideas and conclusions from bERLinProCamp 2019

The Energy Recovery Linac (ERL) paradigm offers the promise to generate intense electron beams of superior quality with extremely small six-dimensional phase space for many applications in the physical sciences, materials science, chemistry, health, information technology and security. Helmholtz-Zentrum Berlin started in 2010 an intensive R\&D programme to address the challenges related to the ERL as driver for future light sources by setting up the bERLinPro (Berlin ERL Project) ERL with 50 MeV beam energy and high average current. The project is close to reach its major milestone in 2020, acceleration and recovery of a high brightness electron beam. The goal of bERLinProCamp 2019 was to discuss scientific opportunities for bERLinPro 2020+. bERLinProCamp 2019 was held on Tue, 17.09.2019 at Helmholtz-Zentrum Berlin, Berlin, Germany. This paper summarizes the main themes and output of the workshop

Optimization of Beam Transportation in Commissioning of the Compact ERL Injector at KEK

In the commissioning of the compact ERL (cERL) injector at KEK, to demonstrate acceleration and transportation of low emittance and high charge electron beam without degrading the beam quality is an important topic. To achieve the optimum condition in a real accelerator, development of beam tuning methods is indispensable because of existence of errors for accelerator components. In the commissioning of the cERL injector, we have developed beam tuning methods for each accelerator component, e.g. photo-cathode DC gun, solenoid magnet, corrector magnet, bunching cavity and superconducting cavity. In these methods, we measured the responses of beam parameters, e.g. beam position, beam size and beam energy, and corrected the model based on the measured response. In addition, to approach the target optimum condition for the whole injector, not only individual correction for each component but also total optimization throughout the injector based on experimental method is required. In higher charge operation with 7.7 pC, we carried out the test of the total optimization. We will report these beam tuning methods and preliminary results of the total optimization.This work was supported by JSPS KAKENHI Grant Number 15K04740.The 28th Linear Accelerator Conferenc

Discrepancy of neural response between exogenous and endogenous task switching : an event-related potentials study

Task switching is a well-known cognitive paradigm to explore task-set reconfiguration processes such as rule shifting. In particular, endogenous task switching is thought to differ qualitatively from stimulus-triggered exogenous task switching. However, no previous study has examined the neural substrate of endogenous task switching. The purpose of the present study is to explore the differences between event-related potential responses to exogenous and endogenous rule switching at cue stimulus. We modified two patterns of cued switching tasks: exogenous (bottom-up) rule switching and endogenous (top-down) rule switching. In each task cue stimulus was configured in order to induce switching or maintaining rule. In exogenous switching tasks, late positive deflection was larger in the switch rule condition than in the maintain rule condition. However, in endogenous switching tasks late positive deflection was unexpectedly larger in the maintain rule condition than in the switch-rule condition. These results indicate that exogenous rule switching is explicit stimulus-driven processes whereas endogenous rule switching is implicitly parallel processes independent of external stimulus

New injection scheme using a pulsed quadrupole magnet in electron storage rings

We demonstrated a new injection scheme using a single pulsed quadrupole magnet (PQM) with no pulsed local bump at the Photon Factory Advanced Ring (PF-AR) in High Energy Accelerator Research Organization (KEK). The scheme employs the basic property of a quadrupole magnet, that the field at the center is zero, and nonzero elsewhere. The amplitude of coherent betatron oscillation of the injected beam is effectively reduced by the PQM; then, the injected beam is captured into the ring without largely affecting the already stored beam. In order to investigate the performance of the scheme with a real beam, we built the PQM providing a higher field gradient over 3  T/m and a shorter pulse width of 2.4  μs, which is twice the revolution period of the PF-AR. After the field measurements confirmed the PQM specifications, we installed it into the ring. Then, we conducted the experiment using a real beam and consequently succeeded in storing the beam current of more than 60 mA at the PF-AR. This is the first successful beam injection using a single PQM in electron storage rings