LANSCE’s TARGET 1 HARP BEAM DISPLAY FORMARK IV TARGET UPGRADE
A. Walker, E. Kerstiens - Los Alamos National Laboratory, Los Alamos, NM 87545, USAAbstract

The Los Alamos Neutron Science Center (LANSCE) completed
upgrades to its 1L Target Facility, which included installing thenew Mark IV target assembly. This added a third tungsten target
located upstream of the other two targets. Prior to Mark IV, beam
centering on target was achieved by using thermocouples
mounted to the quadrants and center of the upper target coolantchamber. It is slightly offset from center of the old upper target
and it shadows several of the thermocouples previously used tocenter beam on target. This required adjustments to thediagnostic tools utilized to monitor position of the H- beam that isbeing delivered to the 1L target. The original display included thethermocouple readouts and displayed a visual beam profile andposition taken from an upstream harp. With some of thethermocouples now being shadowed, an image overlay wasadded to show where the harp’s measured beam position isrelative to both the upper and middle targets. This gives thebeam operations team an additional level of awareness when it
comes to thermocouple temperatures, beam steering, and beamtuning.

New Mark IV Target

Improved Opportunities For Experiments
The Mark IV target was installed during the beam outage in2022. Initial testing and commissioning was performed during
the beam run cycle for 2022, and beam on target from 60 to 85
microamps. 2023 expects to see full production beam of 90+
microamps.

Target Assembly

Three different target assemblies are utilized to provide neutrons
to up to 15 different flight paths for experiments at varyingenergies. The upper target sits vertically, so getting an accurate
picture of the beam profile is key due to thermocouple shadowing
and neutron moderation.

1L HARP Diagnostic

The 1L (Target 1) HARP diagnostic is a set of wires spaced out
in the beam line to gather a beam profile. An electrical current isinduced in them proportional to beam intensity, which shows thebeam profile similar to the wire scanners. The upside to theHARP is it is constantly in the beam line and due to that can beprovide constant updates to the beam position. The 1L HARP
data can be utilized in a double-gaussian fit algorithm to provide
a beam position and intensity map.

Upper Target Assembly

New Target Challenges

Showing a visual representation of the beam profile is achallenging prospect. When the Mark IV target was installed,there are some thermocouples that are getting “shadowed” by
the upper target and a water moderator. This shadowing causes
the thermocouples to indicate lower than the beam intensity
would normally lend itself to, so a graphical overlay needed tobe created in order to represent the location of those moderators
to indicate which thermocouples might be shadowed.

New Mark IV Target Assembly Installed In 2022

1L HARP Wires

Other Diagnostics

Wire Scanners
1L (Target 1) wire scanner 1, 2, and 3 provides a picture of thebeam profile as it is being directed to the target, but don’t
provide a “live” status of the beam in the event of a tune change.
They utilize a single wire inserted in steps in order to get a beamprofile. This “live” status is extremely important, and the wirescanners cause significant beam spill making them ineffectivefor the information needed to visualize.

Simulated Beam

A simulated beam profile is shown to give an indication how thebeam position is graphically represented on the screen. Theintensity changes from red (most beam) to purple (least beam).
Black indicates no beam in that area.

1L Target Temperatures And Beam Position Screen With New Overlay

Above is the temperature and beam position with the newoverlay showing the moderators, thermocouples, temperatures,and (when on) beam position. The water moderator will
moderate the neutrons differently than the tungsten target stackand the air, so differentiating between how the thermocouples
might react is an important tool to utilize when determining how
the beam is centered and if the beam is reacting properly tochanges in the tune.
••••

1L Target Temp. And Beam Position Screen With Simulated Beam

1L (Target 1) Wire Scanner 3* This work was supported by the U.S. Department of Energy through the Los Alamos
National Laboratory. Los Alamos National Laboratory is operated by Triad National
Security, LLC, for the National Nuclear Security Administration of U.S. Department ofEnergy (Contract No. 89233218CNA000001). adwalker@lanl.gov
LA-UR-23-30041
Managed by Triad National Security, LLC, for the U.S. Department of Energy’s NNSA.

Pink – Thermocouples (Squares) and beam pipe (Circle)
Gold – Water moderator (Diagonal)
Silver – Tungsten Target (Diagonal)
Other Area Inside Circle – Air (Not Moderated)