The Meson Production Targets in the high energy beamline of HIPA at PSI

Dear reviewer, thank you for the review and the kind words about our manuscript. 1) The 450 kW dissipated energy for the beam dump looks indeed surprising and you are not the first one wondering about. First, using a 40 mm target, the beam dump stands only 1.6 mA as maximum current on Target E. In Target E and collimator system about 30 % is lost. Therefore, we end up with 1.15 mA or 644 kW (using 575 MeV as some energy is lost in the Target E). The value of 450 kW is calculated from the water flux and the temperature difference of out-going to in-coming water. This value fits very well to an old calculation of Gerd Heidenreich. Another 50 kW is expected for the local shielding left and right of the collimator and 40 kW distributes in the shielding above the collimator according to simulations. The remaining energy is dissipated in the surrounded shielding. 2) Yes, indeed this is a typo. Thank you. It is corrected in the new version. 3) Gerd Heidenreich is indeed the developer of both target stations, the collimator system and the beam dump. I am already in contact with him and he agreed to review our design for the HIMB station. It is a pleasure for me to acknowledge him for the design, which lead to a long lasting and high performing target station. Urs Rohrer was not involved in the target station development but into the beam line design. However, a large part of the success of the target stations as well as the exchange flasks can be devoted to Ake Strinning, the engineer bringing the design ideas of Gerd to life. Michael Wohlmuther was mainly involved in the simulations for the SINQ and UCN target stations, not in the technical design or operation of the meson target facilities. However, as a group leader he was supporting the ANSYS simulations and I will acknowledge him for this.

With kind regards,

Daniela Kiselev

Dear Claude, thank you for the positive rating of our paper and the in-depth review. All corrections were made as you suggested. Below you find a few comments to the most interesting ones: 4) Be contamination: Although I was expecting this problem, I never explicitly heard about. Probably the so called “Be flushing”, which sucks the air into the vacuum pipe to avoid spreading of the contamination, solved the issue. It is still used during the target exchange. 8) Ratio of positive to negative cloud muons: Indeed, it is more a factor 3-4 than an order of magnitude. I probably mixed it with surface muons. 10) Years of references added. 11) Good idea to mention the reason for the naming. Now I know even who it invented!

Best regards, Daniela

The most important changes are listed above.