Introducing Ultra-Low Energy Ion Implantation of Radioactive Isotopes at ISOLDE, CERN for (Near-)Surface Characterization: The ASPIC and ASCII Vacuum Chambers
Round 1
Reviewer 1 Report
Correction, page 8, line 270: "figure 4" should read "figure 5"
Author Response
Dear reviewer 1,
Thank you for suggested correction. Indeed, on page 8, the text was incorrectly referring to figure 4, whereas it should have been referring to figure 5. This have been amended in the manuscript.
Many thanks for the correction!
Sincerely,
Dr. Koen van Stiphout
Reviewer 2 Report
The authors Stiphout et all present a report on the refurbishment of the ASPIC chamber at ISOLDE/CERN for low energy implantation of radioactive ions under UHV conditions. Their main technical goal was to replace the former thermal soft-landing technique by a low energy implantation system called ASCII working at 0-60 keV acceleration energy with focus on energies below 100 eV. The authors simulated the performance of the new system by means of the SIMION program and also gave technical details of the ASCII accelerator being similar to the ADONIS setup of University Göttingen.
Generally, the near surface implantation of dilute radioactive probe atoms for determining the hyperfine parameters are highly desired, especially for 2D materials as stated in the paper. However, the text at many points is written in a sloppy way, e.g.
on page 3 "PAC spectroscopy is a hyperfine technique" should rather sound ".. provides information of the hyperfine interaction ..."
on page 3: "By measuring the correlated angle" should rather sound "by measuring the angular correlation ..."
generally the words "nucleus" and "atom" are used as synonyms which is incorrect. Hyperfine Interaction povide informations on the electronic and magnetic surrounding of the isotope nucleus, not the atom of the probe.
on page 5: "freeing up the main manipulator for more sample preparation." is unspecific
on page 6: "ions impinging on the sample at an angle" is unspecific. I guess, the angle should be adjustable in a certain range to the surface normal.
Sometimes insead of the voltage in kV the energy dimenson keV is wrongly used.
On page 6 there seems to be something missing: "the crystallinity of sample surfaces.... Finally"
On page 8 it is stated, that one can investigate the beaviour of the beam by only simulating. This brings the question whether the setup was tested hands on already.
A big problem is the sentence: "Due the limited space within the current ISOLDE experimental hall, it is possible that one or both chambers would be installed individually, and used accordingly." This sentence gives no information besides that the space at Isolde is limited. So it should be deleted completely. Since readers of this article might understand it as an advertisement and invitation to perform experiments with the new system, it should be clearly stated, if it can be used at ISOLDE and from when.
Unfortunately, direct experimental proof of the function of the system is missing in the paper, since "At the time of writing, the final tests of the chambers’ functionality are being performed". I dont think that such tests are mandatory for this first publication, but if there are such tests obviously going on, I strongly recommend the authors to describe some first hands on experimental results once they are done, since in addition to the simulations, this would increase the quality of the paper.
Author Response
Dear reviewer 2,
Many thanks for the important and helpful suggestions. We have amended the paper according to your suggestions; a detailed overview of the changes can be found in the attachment.
Sincerely,
Dr. Koen van Stiphout
Author Response File: 
Author Response.pdf
Reviewer 3 Report
Radioactive isotopes are important research fields of nanostructures. Ultra-low energy ion implantation was discussed in the article. ASPIC and ASPIC's ion implantation chamber were designed. The research is worth publishing before minor questions are answered.
(1) the area of beam
(2) the current of beam
(3) how to precise control the holder temperature.
(4) the space of the chamber.
Author Response
Dear reviewer 3,
Thank you for your review, and the suggested amendments. We have corrected our manuscript accordingly, as follows:
- In the part concerning the ion beam simulations, we have specified the typical area and current of ion beams used in ISOLDE, which are also the parameters used in the simulation.
- We have indicated in the manuscript how the temperature is controlled in either chambers.
- In the captions of the images of the two vacuum chambers, we have indicated the respective dimensions of the main body of the chamber.
We hope we have amended the paper in a satisfactory way.
Sincerely,
Dr. Koen van Stiphout
