Showing 11 results for Author: Jim G. Janney
Mar, 2026
Conference Paper
The Second Target Station (STS) at Oak Ridge National Laboratory will be a 700 kW pulsed spallation neutron source designed to provide the world's highest brightness cold neutron beams. In order to produce the required neutron performance, two compact liquid hydrogen moderators are located adjacent to the tungsten spallation target and must be supplied with less than 20 K…
Oct, 2025
Journal
With the Second Target Station approaching its final design phase, a detailed neutronics evaluation of its critical components is necessary. Optimizing the dimensions of the two cold-source moderators that are at the heart of this facility presents a multi-objective optimization problem for which an accurate geometric description is crucial. We have applied a fully automat…
Sep, 2015
ORNL Report
The mechanical properties of the proton beam window (PBW) at the Spallation Neutron Source (SNS) are altered during operation by high-energy proton irradiation, resulting in a slight increase in strength and significant decrease in ductility. Due to concerns with loss-of-ductility in the solution annealed (SA) Inconel® 718 window material, a maximum administrative dose lim…
Jun, 2014
Conference Paper
An effort is underway at the Spallation Neutron Source (SNS) to change the design of the 1st Generation high-nickel alloy proton beam window (PBW) to one that utilizes aluminum for the window material. One of the key challenges to implementation of an aluminum PBW at the SNS was selection of an appropriate joining method to bond an aluminum window to the stainless steel bu…
Apr, 2014
Conference Paper
The Spallation Neutron Source (SNS) at the Oak Ridge National Laboratory (ORNL) has operated at unprecedented power levels for a short-pulse spallation source. Target operations have been successful but not without difficulties. Three targets out of the eight used to date have ended life unexpectedly causing interruptions to the neutron science users. The first of a kind m…
Apr, 2013
Conference Paper
A rotating solid target design concept is being developed for potential use at the second SNS target station (STS). A long pulse beam (~ 1 msec) at 1.3 GeV and 20 Hz is planned with power levels at or above 1 MW. Since the long pulse may give future opportunities for higher power, this study is looking at 3 MW to compare the performance of a solid rotating target to a merc…
Feb, 2013
Conference Paper
An aluminum proton beam window design is being considered at the Spallation Neutron Source primarily to increase the lifetime of the window, with secondary advantages of higher beam transport efficiency and lower activation. The window separates the core vessel, the location of the mercury target, from the vacuum of the accelerator, while withstanding the pass through of a…
Feb, 2012
Conference Paper
A rotating target for the second target station (STS) at SNS has been identified as an option along with a mercury target. Evaluation of the rotating target alternative for STS has started at 1.5 MW which is considered an upper bound for the power. Previous preconceptual design work for a 3 MW rotating target is being modified for the lower power level. Transient thermal a…
Feb, 2011
Conference Paper
As the Spallation Neutron Source (SNS) beam power is increased, the collimator systems are becoming correspondingly more important. The High Energy Beam Transport (HEBT) transverse collimators are now routinely used during neutron production. We are in the process of redesigning the HEBT momentum collimation system due to problems with gas production from radiolysis. The R…
Aug, 2010
Conference Paper
After several years of operation, the SNS now enters an era of megawatt class operation. At this intensity level, the target will be operating closer to its engineering limits and the beam profile on target must be carefully controlled. During commissioning and early operations, a temporary imaging system was used to measure the proton density on target. This system was no…