CSNSII is an upgrade project of China Spallation Neutron Source (CSNS), which needs to increase the beam power from 100kW to 500kW. In order to find a suitable working point area in advance and evaluate the influence of space charge effect on CSNSII, the measurements of beam loss with different tunes on CSNS was carried out and beam loss simulation in transverse tune space on CSNSII has been performed using PyORBIT code. We gave the relationship between the beam survival rate and the working point, compared four groups of candidate working points and confirmed the influence of the fourth-order resonance on the beam through the single particle model.

A compression of the ESS proton pulse from the present 2.86 milliseconds to a few tens microseconds which is better matched to the moderator time constant of thermal neutrons would considerably boost the performance for many instruments at ESS. Generating such a proton pulse with preserved instantaneous beam power requires a storage ring to be added to the ESS accelerator. Such a ring has been studied within the ESSnuSB neutrino super-beam study. The proton pulse length extracted in single turn extraction from this ring would be 1.2 microseconds long which could be destructive for the present ESS target and is very short compared to the moderator time constant. The more desirable medium length pulse could possibly be generated by multi-turn extraction. Another way to generate the longer pulses is to extract a bunch train using fast strip line kickers but this would require a larger storage ring. Using a “bunch train” has been successfully applied at the CERN ISOLDE facility to avoid destruction of sensitive liquid metal targets used for Nuclear Physics experiments. Other challenges are linked to the injection into the storage rings and the understanding of the target, moderator and neutron extraction systems with short and medium pulse length. We will in this presentation review the technical challenges linked to a future medium pulse length ESS facility and the ways proposed to address them for the accelerator and target.

Accelerator facilities are among the most complex projects, integrating advanced engineering systems and components. At the ESS, the need to visualise the intricate integration activities has led to the development of Aggregation Diagrams (ADs). The diagrams follow the facility breakdown structure with sections and system diagrams showing their integration of the devices with enabling and interfacing systems such as the vacuum, cooling, power suppliers and control systems. Commissioning diagrams have also been developed and are used to visualise the main steps and events in the commissioning of the accelerator. The main advantage of using ADs is to help in the activities planning, provide easy access to high-level plans and develop a standard tool that could be used among the different work packages. In this paper, we present the workflow on the development of ADs giving some examples of their use in the activities planning at the ESS.

The Los Alamos Neutron Science Center (LANSCE) is a very flexible H-/H+ 800-MeV proton linear accelerator and storage ring that serves five distinct user facilities in support of LANL’s national security mission and commercial applications. It is unique because of the intensity and energy spectrum of the neutrons produced. The Isotope Production Facility (IPF) operates using an H+ beam line at 100-MeV. The Proton Radiography Facility uses the 800-MeV H- beam stripped to protons. The Ultra-Cold Neutron (UCN) Facility, the Lujan Center, and the Weapons Neutron Research (WNR) Center all use spallation neutrons from tungsten targets with water and liquid hydrogen moderators for Lujan, a solid deuterium moderator for UCN, and no moderation at WNR. These spallation targets all receive 800-MeV beam each with a unique beam pulse structure specific to that target. LANSCE celebrated its 50-year anniversary of 800-MeV beam during the summer of 2022. We will summarize operational experiences and challenges at a half-century old accelerator facility, including recent improvements and current upgrade plans.

The Los Alamos Neutron Science Center (LANSCE) is a highly versatile H-/H+ 800-MeV linear accelerator that serves five distinct user facilities. Currently, H+ is accelerated through the drift tube linac down a stub line for the Isotope Production Facility at 100 MeV. The other four user facilities at LANSCE use the H- beam accelerated to 800 MeV. The H+ beam had historically been accelerated to 800 MeV for Area A operations but has not done so for over two decades. There are potential benefits to accelerating the H+ beam to 800 MeV to serve the Proton Radiography and Ultra-cold Neutron facilities in terms of potentially higher peak currents, improved emittance, higher ion source reliability, etc. A study was commissioned this year to conduct a cost/schedule/benefit analysis of converting from H- operations to H+ operations for these two facilities. The status of that study will be discussed.