Review Reports - Detectors and Shieldings: Past and Future at LUNA

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Nuclear reactions of astrophysical interest typically occur at deep sub – Coulomb barrier energies. Therefore, their cross sections are tiny making direct measurements extremely hard. Although several techniques have been developed for the indirect determination of the cross sections of such reactions, the direct measurements (when possible) present the vital advantage to omit significant experimental or/and theoretical challenges in the cross section estimation. It is understandable that a direct cross section measurement in the astrophysically relevant energy range typically requires a high – intensity beam, ultra – pure targets, a large detection efficiency etc. The underground environment of INFN – LNGS in central Italy provides also the necessary reduction of the cosmic – rays background which is crucial for such low – cross section measurements. LUNA is a unique facility of LNGS providing to the scientific community with high – quality experimental data on nuclear reactions of astrophysical interest for many years.

The present article presents an overview of significant technological aspects of LUNA related to the detection and shielding setups, which are vital for the successful experimental campaign of the collaboration. A part of the scientific information and figures of the manuscript may be found also in theses and articles cited in the reference list however, it remains an important overview of this information for all reactions under investigation highlighting the experimental challenges and how they are faced out. In conclusion, there is no doubt that the article is scientifically sound, well written and its content is certainly appropriate for the journal Universe. However, prior to publication, I recommend the authors to consider a few specific comments mentioned below.

I. In the first paragraph of the introduction the essential information on the field is given. Nevertheless, I suggest enriching the paragraph with state – of – the art references (review articles or/and textbooks). A recent article by R. Buompane et al., Nuclear Physics Mid Term Plan at LNGS, Eur. Phys. J. Plus, 2024, 139, 224 is also highly recommended to be cited in the introduction.

II. In the 3^rd paragraph of the introduction, the reader can find some quantitative information about the background reduction. Although such reduction is impressive itself, it would be also interesting providing some typical signal – to – background ratios in order to be evident how the remaining background affects the measurements.

III. In continuation to my previous comment, in several subsections of sections 3 and 4, the reader can see in enlightening spectra how the background was reduced in LUNA setups. It would be nice to provide –if available– some quantitative information on the background reduction and signal – to – background ratio for each case.

IV. Some minor comments/suggestions may be found below:

1. Page 3, line 133: “…contribute <5 in the astrophysical temperature range of interest.” → Perhaps something is missing here (units?). Please correct or elucidate.

2. I do not understand why 3.1. is a sub–section while, 3.1.1 – 3.1.5 are sub–sub–sections. Please correct or elucidate.

3. Page 8, lines 230 and 246: although quite clear to me, it should be more precisely defined what “close geometry” means.

4. Page 10, Caption of Fig.8: it is written that the left panel of the figure is adapted from Ref. [53]. I think that the figure was adapted from Ref. [8] or a similar one.

Author Response

Referee's comments are in black and authors' reply in blue

In the first paragraph of the introduction the essential information on the field is given. Nevertheless, I suggest enriching the paragraph with state – of – the art references (review articles or/and textbooks). A recent article by R. Buompane et al., Nuclear Physics Mid Term Plan at LNGS, Eur. Phys. J. Plus, 2024, 139, 224 is also highly recommended to be cited in the introduction.

We added references to the introduction section, as suggested by the referee.

In the 3^rd paragraph of the introduction, the reader can find some quantitative information about the background reduction. Although such reduction is impressive itself, it would be also interesting providing some typical signal – to – background ratios in order to be evident how the remaining background affects the measurements.
In continuation to my previous comment, in several subsections of sections 3 and 4, the reader can see in enlightening spectra how the background was reduced in LUNA setups. It would be nice to provide –if available– some quantitative information on the background reduction and signal – to – background ratio for each case.

We tried to add more quantitative information, when possible, for the different scientific cases.

Some minor comments/suggestions may be found below:

Page 3, line 133: “…contribute <5 in the astrophysical temperature range of interest.” → Perhaps something is missing here (units?). Please correct or elucidate. Done
I do not understand why 3.1. is a sub–section while, 3.1.1 – 3.1.5 are sub–sub–sections. Please correct or elucidate. Done
Page 8, lines 230 and 246: although quite clear to me, it should be more precisely defined what “close geometry” means. Done
Page 10, Caption of Fig.8: it is written that the left panel of the figure is adapted from Ref. [53]. I think that the figure was adapted from Ref. [8] or a similar one. Done

Reviewer 2 Report

Comments and Suggestions for Authors

I have reviewed the manuscript "Detectors and shieldings: past and future at LUNA" by C. Ananna et al. This is a very clear and comprehensive review of recent nuclear astrophysics results at LUNA with a focus on the role of shielding and detector implementation. It will be of broad interest to researchers in nuclear physics. The paper is very well written and quite enjoyable to read. I found no significant questions or problems with the scientific discussion or the various conclusions made throughout. There are several minor issues that should be corrected prior to publication, listed below. Otherwise I highly recommend acceptance of this paper in Universe.

1. There are many places where the expected "%" symbol is missing, perhaps a LaTeX error, see for example lines 87, 133, 149, 223.

2. Similarly the degree symbol is missing in line 149.

3. Thickness units are missing for the delta-E detectors in lines 263, 264.

4. Line 116, is this photopeak efficiency relative to NaI? Please make that clear.

5. Line 170, is this absolute photopeak efficiency?

6. The definition of AGB should be moved to the first appearance at line 220

Author Response

Referee's comments in black and authors' reply in blue

There are many places where the expected "%" symbol is missing, perhaps a LaTeX error, see for example lines 87, 133, 149, 223. Done
2. Similarly the degree symbol is missing in line 149. Done
3. Thickness units are missing for the delta-E detectors in lines 263, 264. Done
4. Line 116, is this photopeak efficiency relative to NaI? Please make that clear. When speaking about detectors, relative efficiency always refer to the photopeak efficiency compared to NaI, so we think relative efficiency is clear
5. Line 170, is this absolute photopeak efficiency? Done
6. The definition of AGB should be moved to the first appearance at line 220 Done

Reviewer 3 Report

Comments and Suggestions for Authors

It is not clear for me the type of this work. Taking into account the structure and the text, I suppose that this is a review (10 from 12 figures are all/adopted) on the previous results and perspectives in the field at LUNA Experiment.

After the quantity and quality of the presentations I expected at more clear and facts based conclusions. These are very generally and not clear connected with those presented in the text

Moreover, there are a few places where there are some incomplete information (rows 44, 132-134, 400 etc), but these is is to solve.

Author Response

Referee's comments in black and authors' reply in blue

The paper type is review.

After the quantity and quality of the presentations I expected at more clear and facts based conclusions. These are very generally and not clear connected with those presented in the text

We revised the conclusion.

Moreover, there are a few places where there are some incomplete information (rows 44, 132-134, 400 etc), but these is is to solve. Done