NEAR: A New Station to Study Neutron-Induced Reactions of Astrophysical Interest at CERN-n_TOF

Round 1

Reviewer 1 Report

The paper is devoted to the NEAR, ner experimental area at the CERN-n_TOF experiment, which is planned for studies of neutron capture cross-sections, especially the ones which are potentially significant for astrophysics. The paper is well written and describes the experimental setup very well. Also, GEANT4 is performed in order to choose the best setup for future runs. In addition to that, the physics motivation of the experiment and the measurement of several dedicated cross-sections are discussed. The paper can be published after minor English checks.

In addition to that, real experimental data will be more interesting than the description of the experiment and declaration of its scientific targets. Probably it has the sense to include or somehow present the current schedule of the experiment. In the present version of the paper, no deadlines are given, so we can only guess when we will possibly get the new data for astrophysics.

Minor checks:

1. Universe should be capitalized.
2. Nuclear Astrophysics should be decapitalized.
3. str 32. What does "white" spallation mean? Probably the explanation should be included in the text for out-of-field readers.
4. str 47. "since July 2021" -> ""since July 2021,"
5. "r-process" and "s-process" should have "-" everywhere in the text.
6. str 118. I found only one source with the "n-process" term. Is it a common term?
7. str 161. What is an "explosive-bonded joint"?
8. str 165. Delete repeating "of"
9. str 173. "Inconel ( the latter" -> "Inconel (the latter"
10. str 175. "neutron response. [20]." -> "neutron response [20]."
11. str 180. I recommend reformulating the sentence, currently, it sounds like "In order to shape..., results show" -- that sounds nonsense.
12. str 189 "form" -> "from"
13. fig 7. Black and red are totally the same. It is correct? Why?
14. str 197 "so to" -> "to"
15. str 218 Where is the verb?
16. str 222 "in time ∆t." -> "in time ∆t)."
17. str 239 "HPGe" -> "HPGe (High Purity Germanium)"
18. str 244 del repeating high
19. str 251 Where is the verb?
20. str 267 del ending dot
21. str 274 "More in detail, We proposed" -> "More in detail, we proposed"
22. str 275 should SACS be MACS?
23. str 277 "planned" -> "planned to be measured"
24. str 290 "multimessanger" -> "multimessenger"
25. str 370 "there are few and discrepant reported cross-sections in literature": refs should be provided.
26. none of arxiv URLs in the reference list are active, at least during the preparation of the referee report.

Author Response

Dear Referee,

thank you for revising our paper. We read carefully your suggestions and we agree with all of them: corrections have been made accordingly.

Between all the corrections made, we would like to stress that at:

- str. 32 “white spallation source” meaning has been added

- str. 161 we explain now what “explosive-bonded join” means

- str. 180 we have reformulated the sentence

- str. 370 two more references have been added to show the recent discrepancy in literature

The scheduling of the next experiments would be decided after the next meeting of the CERN Scientific Commission fixed at the first week of June 2022.

Best Regards,

Gianpiero Gervino

Reviewer 2 Report

Ref: NEAR: a new station to study …

By G. Gervino et al.

The manuscript describes a new experimental station, dubbed NEAR, at the well established n_TOF facility at CERN. The station is much closer to the target of the spallation source and therefore, offers higher neutron fluxes. This in turn allows the possibility to measure neutron cross sections using mass samples, including those of short-lived unstable isotopes. The authors insist on its usefulness for measuring MACS for reactions of interest in nuclear astrophysics. Using collimators, moderators and filtering systems, the characteristics of the neutron beam (neutron intensity and energy distribution) can be adjusted, making it useful for modeling environments and temperatures existent in various stellar processes. The authors present results of extensive Monte Carlo simulations on adjusting station’s characteristics and sketch its initial use for testing and commissioning it.

The facility is interesting, useful, has been built, is working and ready to use. As such, the paper is worthy of publication.

However, I have a number of observations.

In Section 2 “Stellar evolution investigations” there are a few statements that are either not exactly right or not well expressed:

- on lines 76-77 , the statement “and the heavy elements in them appear to be made exclusively by the rapid neutron capture …” is not correct. The phrase leaves the impression that the authors talk about nucleosynthesis of “metals”, and the elements in this category were being produced by a series of processes starting with 3alpha, He-burning, fusion reactions, s- and r-processes, etc… In fact the statement is contradicted by the remainder of the paragraph. Rewrite carefully!

- on line 100 “availability” is probably meant to be “lack” of a large …

- on line 107-8, the neutron density for the “i-process” is misplaced

- a few typos on lines 165, 220 (“these case”), 244, 275 (SACS), 326-7 “That the … spans), 331 (maximum electron energy), 381 …

In terms of information, I suggest the authors indicate the expected neutron fluxes and to estimate and present the mass of samples and the lifetime limits they expect for the radioactive species they plan to measure (more than we have in lines 62-66). An estimate of the range of temperatures expected to be covered with the setup would be very good for the reader. There is no indication of the background expected to be seen by the GEAR station (which I believe is near NEAR). Is it going to be a problem?!

In conclusion I recommend  the paper for publication in Universe after the suggested observations are considered.

Author Response

Dear Referee,

thank you for revising our paper. We read carefully your suggestions and we agree with all of them: corrections have been made accordingly.

All the substantial changes in Section 2, done following your suggestions, are in red. All the typos have been corrected.

At the Conclusions we stress the neutron energy range of interest for investigating AGB stars and massive stars. An estime of the minimum thickness and upper lifetime limit of the activation samples are given.

An indication about the GEAR HPGe spectrometer background has been added.

The expected neutron flux and its energy distribution is shown in Fig. 7, figure captions have been improved.

Best Regards,

Gianpiero Gervino