KLF beamline meeting - December 5, 2024

Agenda

• Announcements

• FLUKA simulations with 20% CPS radiator (Pavel)

• W-plug temperature estimates for 20% radiator (Hovanes)

• Beamline studies with GEANT4 (Richard)

• Any other business

Minutes

Present: Hovanes, Pavel, Vitaly, Tim, Moskov, Eugene, Igor, Sashi, Beni, Richard, Mikhail, Marshall.

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• Pavel continues studying the option of 20% radiator in FLUKA. The W-plug length was 14cm and Be-target length was 40cm. The cylindrical Be-target in this FLUKA model is embedded in a copper block that is supposed to cool the Be-target and also absorb beam power passing around the Be-target.

• Pavel also included the tungsten material of KLF Active Collimator ~50cm in front of the KPT assembly.

• The γ-beam width in the cave with 20% radiator is considerable wider than with 10% radiator. As the AC diameter is only 6cm wide, there will be large overlap between the beam envelope and AC material leading to power deposition in AC and elevated radiation in the cave.

• According to FLUKA, each tungsten wedge absorbs about 90W from the photon beam. Thus Pavel's estimate for the total power deposited in AC is about 400W.

• Radiation dose rate from neutrons doubled compare to that without AC. γ-dose-rates did not change so much.

• Tim commented that Active Collimator is attached to the KPT assembly and the long distance between KPT and AC may cause elevated radiation rates.

• Moskov asked for a summary of the presentation. Pavel answer was that this is work in progress and that he will have more updates at the future meetings.

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• Hovanes showed his thermal analysis of the tungsten plug and Be-target for the 20% radiator scenario.

• First, Hovanes used power deposition map for 10% radiator evaluated by Vitaly a few years ago in FLUKA, and multiplied the power in that map by a factor of x2. The resulting temperature in the tungsten plug estimate for such power deposition distribution was pretty high, T_max=350 ⁰C.

• Then Hovanes used the new power deposition map from Pavel's FLUKA simulations for 20% radiator. He considered a single block containing Be-target, W-plug, and copper around the Be-target as a single body cooled from the four sides by water. The temperature in the plug and the Be-target was about the same as for 10% radiator.

• Eugene would like to see the same simulation with 10% radiator as he thinks it is suspicious that the temperature of the tungsten plug did not change. Hovanes pointed out that we have copper block around the Be-target with 20% radiator option. This takes away 2.8 KW power from reaching the tungsten plug.

• Hovanes thinks that from thermal analysis point of view, 20% radiator option is feasible. But cooling inside of KPT assembly would need to be substantially modified.

• Hovanes also showed the three distinct options for KPT assembly that can be currently pursued by KLF. But a decision needs to be made by the KLF collaboration leadership which way to go. The decision needs to be made very soon as delays will negatively impact KLF construction schedule as well as the NPD scheduling process.