On the Limitations of Positron Annihilation Spectroscopy in the Investigation of Ion-Implanted FeCr Samples
and Vladimir Krsjak 1,2Round 1
Reviewer 1 Report
Dear authors,
Thanks for presenting this manuscript for publication. You are raising interesting points around the use of positron annihilation lifetime spectroscopy to identify near surface defects as a means to investigate irradiation damage in nuclear materials. In particular, you are highlighting the fact that, due to their non-uniform implantation profile, information retrieved during annihilation events is affected by that profile. You are proposing to use the resulting depth distribution function to correct the results of the spectroscopy in quantifying damage. This would allow retrieving a more accurate measure of damage from ion irradiation than using the PALS alone.
My main concerns relate to 1- the robustness of the approach, and 2- the English style often makes following the manuscript challenging
1- On the face of it, the approach presented is sound, and indeed such correction is applied in other experimental techniques which rely on a particle interaction (incl. X-ray techniques where the depth distribution function is well-described). The problem is that you do not provide the depth of analysis that would justify using that approach to investigate radiation damage. The experimental data doesn't fit the model, and the difference is brushed away rapidly. The sensitivity of the approach to variation in experimental and analytical input isn't presented. You do not provide the reader with a way to effectively use the method and what will be the benefits of the method. These should be addressed in the manuscript.
When you say "considering positron stopping profile", do you mean that you have corrected the apparent dpa value with the depth distribution function of implanted positron?
If that is the case, why not using the experimental fit, or an extrapolation of the experimental fit, from your experiments in Figure 4 as your depth distribution function to correct the data? this will allow you to compare the sensitivity of your approach on the type of profile chosen for the positron's depth distribution function. On that note, Fig 4. What is the function used to fit the experimental data? It needs to be added.
In addition, how would you recommend to undertake the measurements and your correction method? does one need to perform first a PA depth profile, fit that profile and then conduct PA on the damaged sample?
For both sets of simulations, could you please provide a table or figure comparing what would be the difference in observed damaged from positron annihilation spectroscopy measurements? how big of an impact does it have to not account for the positron depth profile. Another possible way to highlight further the benefits of your approach would be to show what would be expected in Figure 6 if you had not considered the depth distribution function.
2- It is beyond the time I have available to highlight where the text should be better phrased. In general, if you could shorten sentences and chose a more direct form, it will make it easier on the reader. For example, in the abstract "New requirements for materials foreseen for advanced fission/fusion nuclear facilities must inevitably concern their resistance to radiation embrittlement."-> "New materials for advanced fission/fusion nuclear facilities must demonstrate resistance to radiation embrittlement."; In the introduction, "Although the radiation damage presence was also registered at fluences lower than 5x1020 n.cm-2 mostly in so-called heat-affected zones near-weld welds, the cracking probability also depends on other factors as thermal condition, fabrication procedures, coolant purity, levels of fast neutron flux and/or fluences, residual stresses in welds and closed region and specific combination of all factors."->"Radiation damage was also demonstrated at fluences lower than 5x1020 n.cm-2 mostly in so-called heat-affected zones near welds. However, in these conditions, cracking probability may be dominated by other factors such as thermal condition, fabrication procedures, coolant purity, levels of fast neutron flux and/or fluences, residual stresses in welds and closed region and combinations of these factors."
Other tid-bits:
- Abstract: last sentence, please add that this refers to 22Na radioisotope source otherwise it is not sufficiently specific.
- PALS: while it is obvious, it needs to be spelled out.
- The manuscript has incomplete sections at the bottom (all the XX).
I am looking forward to your improved manuscript.
Kind regards,
A reviewer
Author Response
Thank you for comments.
Answers (harmonised to other reviewer comments) are in attached file together with changes indicated in paper.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
This paper discusses the basics of using positron annihilation spectroscopy and Doppler broadening spectroscopy data. They also provide some recommendations on how to improve the validity of positron annihilation spectroscopy data obtained on ion-irradiated samples.
1. The authors need to better convey their findings in the abstract as it is written in a vague manner.
2. Please provide references for the equations used.
3. This paper is a little confusing. Why did the authors put the details of the implantation experiments in the Results and Discussion section? It is strongly recommended that they put these details in the Experimental section.
4. In the caption for Table 1, please indicate what ion specie this is for.
5. The authors claim that they used SRIM software to perform calculations pertaining to the irradiation of steel. However, there are many important details missing from this discussion. For instance, what displacement energy was used for the atoms in the steel? What lattice binding energy was used? The atomic makeup of the target? What type of TRIM calculation?
6. Important details are missing from the Author Contributions, Funding, Data Availability Statement sections.
Author Response
Thank you for comments.
Answers (hamonised to comments of other reviewer) are in attachment together with paper where all changes are indicated.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Thanks for the changes brought to this manuscript. While I encourage you to further refine the English style, it is now in a publishable state.
Kind regards,
A reviewer
Author Response
Dear reviewer,
thank you for your time and effort connected to my paper. We have tried to improve English several times, but English is not our mother tongue....
After next checking we have to ask for help editor.
Best wishes
Vladimir Slugen
Reviewer 2 Report
They adequately improved the manuscript, accept.
Author Response
Dear reviewer,
thank you for your time and effort connected to my paper. We have tried to improve English several times, but English is not our mother tongue....
After next checking we have to ask for help editor.
Best wishes
Vladimir Slugen
