The NEXT Project: Towards Production and Investigation of Neutron-Rich Heavy Nuclides

Round 1

Reviewer 1 Report

The paper describes the NEXT project devoted for production and investigation of neutron-rich heavy nuclides. It is important from astrophysical nucleosynthesis point of view and synthesis of heavy elements as well. Multinucleon transfer reactions will be applied to reach these nuclei.  Superconducting solenoid is used to separate the different transfer products and to focus those of interest to a gas-catcher. From the gas-catcher the ions are transferred and bunched by a stacked-ring ion guide into a Multi-Reflection Time-of-Flight Mass Spectrometer (MR-ToF MS). The MR-ToF MS provides isobaric separation and allows for precision mass measurements. The description of setup, overview of the NEXT experiment and its perspectives for future are given.

The paper is acceptable for publication with some minor changes.

In the section AGOR cyclotron:

It is desirable to give intensities for actual beams used in experiment i.e. 136Xe, 48Ca

Lines 100-104:

It is not clear the reason so low transmission yields for N=126 (of about 15%) while for N=162 it is about 80%. Could it be explained?

Lines 159-160: As for N=126 all nuclides are beta-decaying – do you plan to measure beta-? -With which detectors? It should be clarified.

Figure5. “Drawing of the gas-catcher coupeld by the ion guide coupled to the MR-ToF MS“   -    change „coupeld“ to ”coupled“ and remuve  second ”coupled“

In general:

It will be very useful if you’ll give the expected efficiencies of all parts of setup and total efficiency. Then, using expected cross sections you cold dive an expected total yields of ions on detectors with given actual projectile beam intensities. It is important to demonstrate that the experiment is realistic.    

Author Response

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Reviewer 2 Report

Please give the details of references 19 and 20 so that interested readers can decide the quality of the relevant calculations.  Please be sure to describe the interesting details of Figure 3.

Author Response

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Reviewer 3 Report

The authors present an overview of the design of the NEXT experiment, which will use a solenoid magnet to achieve a high acceptance for MNT reactions. These reactions could be used to produce superheavy elements, of interest to this special issue. The manuscript provides information on all aspects of the experiment, including the primary driver, the solenoid separator, the gas catcher and ion guide, and the MR-TOF separator. 

The article is well-written, has clear illustrations and relevant diagrams. I have only a minor comment and question. 

Page 2, line 40: it is mentioned that in the case of IGISOL, laser ionization of the products is applied. This is not entirely correct; while laser ionization can be considered, so far no laser ionization was used; instead, the use of He in the gas cell means reaction products do not neutralize and are instead extracted ions. See: Spǎtaru, A., et al. "Production of exotic nuclei via MNT reactions using gas cells." Acta Physica Polonica B 51.3 (2020).

In section 2.3: a very nice and detailed overview is given on the gas catcher and the ion guides, but I found no mention of expected (simulated) efficiencies of either device. What is the expected energy and time spread of the bunches extracted from the ion guide? This is of interest since will affect the MR-TOF performance.

In the section 'Status and planned experimental program', it is summarized that NEXT will be used to study the transfermium region with actinide targets. It may be interesting to the reader to get a more detailed overview of which nuclei/isotopes may be within reach with the separator, other than the excellent example of 261Md provided in the body of the text, and more specifically what kind of rates can be expected. Figure 3 gives the relative transmission efficiencies but makes no mention of expected rates with AGOR+NEXT.

 

 

 

 

 

 

 

Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

I have no further comments for the authors