The authors present a novel set of experiments using a new sensor to simultaneously measure neutrons, muons, and gammas. The new sensor is compared to conventional sensors with satisfactory results for longer time periods of integration (i.e. 6 hrs for neutrons). The technology is lighter and potentially a lower cost, which will open up doors for more applications in science and in practical applications. The manuscript is well written and appropriate for the journal. I have a few suggestions that should be addressed prior to publication. Some instances of English grammar and word choice will need to be addressed.

L33: “Runoff generation”

L 40: “More recently, attention”

L 44: “has shown”

Figure 1: Are events outside of the blue and red ovals not included in the analysis?

L165: For the gammas are there any corrections needed for pressure or air temperature/humidity variations?

L247: I would use the SG filter on the neutron/gamma count time series, not the soil moisture time series that have been transformed by the calibration function.

L 302-305: This sentence is confusing and long. Please rewrite.

Figure 7. Will be interesting to compare the Muon detection with the correction factor being proposed by McJannet and Desilets using cutoff rigidity and atmospheric depth with the NMDB historical data. Unfortunately, that work is in the review process still.

Figure 8. So the soil moisture data is from FINAPP and not depth weighted following the Schron method? If you did have gravimetric surveys how would you depth weight them for the gamma sensitivity? From my understanding they would have a similar sensitivity with depth as the neutrons but be a little shallower (10-15cm?)?

Table 1. Iwema et al. 2015 recommends 3 calibrations for estimating N0. From the variability here I would do at least 3 to estimate some uncertainty on N0. I agree additional gravimetric studies are needed, particularly for establishing the gamma to soil moisture dependence, especially when used in cropping systems with significant temporal variations in vegetation biomass. Unfortunately, for CRNS and GRS studies all roads don’t lead to Rome but to more gravimetric sampling :).

Iwema, J., Rosolem, R., Baatz, R., Wagener, T., & Bogena, H. (2015). Investigating temporal field sampling strategies for site-specific calibration of three soil moisture–neutron intensity parameterisation methods. HESS, 19, 3203–3216. https://doi.org/10.5194/hess-19-3203-2015

The study presents a new sensor system to monitor epithermal neutrons, cosmic-ray muons, and total (i.e. non-spectrometric) gamma rays all in one device. The novelty of this work is not only the individual technology of the three components, it is rather the combination of them and its potential for research and applications. Hence, it is important to demonstrate that each of the three signals can be reliably and  simultaneously measured, and how they can be used for the greater good.

The neutron measurements seem to correlate well with traditional neutron detector signals, at least the scale of several days to months. Although the idea of correcting incoming neutron radiation with local muon measurements is not yet established and still an active field of research, the presented sensor may provide a fantastic opportunity to collect a large data set that could help to falsify this hypothesis in the future. The rather high RMSE of soil moisture calibration data and neutron products (up to 10 m3/m3 , Fig 5) is not a big issue, since every neutron probe would probably see similar deviation considering the substatial spatial heterogeneity, biomass, etc. I highly appreciate the elaborate discussion of influencing factors led by the authors.

A major weakness of the study is that no muon data was shown and comparisons to existing muon and gamma data sets are missing. This hinders proper falsification of these two measurement approaches. Many claims made in this study require better rigorous support. If possible, I'd suggest to add data to the study that provides evidence of the proper functioning of all three detectors, since it is key to covince the readers about the reliable measurement of three different particles at once.

The work is highly relevant to the journal and will have a great impact in the science community. However, I suggest major revisions to better streamline the focus of the paper on falsification and evaluation of the three components, of which muons and gammas are yet insufficiently addressed. The detailed comments below could help to quickly address the missing pieces before publication.

1. Major concerns
2. The authors present a new device which combines three existing measurement principles, but only evaluate one of them with conventional devices (here, only neutron counter vs. other CRNS probes). Since the main novelty is the availability of three detectors at the same time, I would have expected also a validation of (or at least evidence for) the proper functioning of the muon and gamma detectors. This could be easily done with existing gamma ray probes from national authorities, and muon telescopes or the global muon network. Also consider plotting measured muon time series together with Jungfraujoch data to identify differences in their response to cosmic rays.
3. Muon processing is a bit vague. Why is there no correction for atmospheric humidity on the muon signal? Where do you get the temperature data from? Local near-surface temperature is probably not suited to represent temperature effects in the upper atmosphere. The authors also mention that long-term local time series have been used to estimate the parameters, but the data is not shown and as they cite Stevanato et al, it is not clear whether this is valid for both, the German and the Italian sites.
4. The authors present excellent agreement of their neutron data with conventional neutron detectors during 6 months. However, it is the short-scale effects which are particularly interesting, e.g. the coincident response to the onset of rain events, to dew formation, to atmospheric variations, to drying periods, etc. They could be different if detection energy or geometry differs, and could eventually shed light on the actual sensor performance. This is not identifiable from the presented data, at least not with the long x-scale chosen in Fig 4. I'd appreciate if the authors could provide a zoom-in of the data that allows for day-to-day analysis and comparison.
5. The authors argue that Jungfraujoch data "completely fails" in correcting neutrons. However, a single evidence is only visible for one (the second) out of many precipitation events (Fig 7). And only in San Pietro, while in Legnaro the performance of Jungfraujoch looks ok, i.e. a small increase of soil moisture is still evident for the small precipitation event. Unfortunatelly, other sites were omitted. And since no measurement of actual soil moisture is presented, any improvemtent of the muon correction over NM correction remains just speculation. It is necessary here to show either additional soil moisture data, or muon vs Jungfraujoch data, or muon vs global muon database data, and to discuss any other influencing effects, such as high atmospheric temperature. Alternatively, rephrase the claims of this study to be more speculative and subject to future work.
6. A better description and discussion of the gamma detection mechanism is missing beyond "0.3-3.0 MeV". How is the signal separated from unwanted gamma rays (e.g., from other energies, or from the detection products from the reactions in the adjacent detectors)? Is there an energy response function? What type of reactions are visible in this range beyond K, Th, and U, and what could be their source or influencing factors other than water accumulation? How is the instrument different from typical gamma-ray sensors used by national authorities or by Strati et al? How does the weak correlation to soil moisture compare to literature values?

Minor concerns

1. Multiple use of the word "good" to describe the performance of the sensor (L45, L69, L70, L73, L230, 253). In a scientific publication -- in contrast to advertising material -- it is necessary to more concretely measure the performance, provide quality statistics and an uncertainty assessment. Sometimes numbers were given in the figures, but mostly missing in the text.
2. Improve description of the particle detection mechanisms and modules used, see comments below. Remember that your audience is GI.
3. Improve language to be more scientific and more concrete (not just "special property", "easily detect", "considred reliable", etc), see comments below.
4. The authors claim to describe the "current state of the art of data processing", while sometimes they are missing out relevant and newer literature (see specific comments below). If the authors do not want to update their processing procedures with newer (but admittedly less established) methods -- which would be ok -- at least the above statement should be removed or properly discussed why the provided approaches were used.
5. The above comment is particularly relevant as the soil moisture presented in Fig 5 sometimes goes below zero, which is a common artefact of the Desilets et al 2010 approach, for instance.
6. The authors seem to advertise a new excel tool to support CRNS calibration and data processing (Baroni et al 2022). Has it been peer reviewed elsewhere? I would reject to publish it as a supplement to this work, since it is very general and out of scope here, and explanation of the methods used were not given in the manuscript.
7. The authors argue that a dedicated soil sampling campaign should be conducted to the evaluate gamma-ray data. However, the soil sample campaigns performed for neutron calibration were partly taken in <25 m distance, I suppose from looking at Fig 3. Wouldn't this be helpful to evaluate the gamma footprint?
8. The authors mention that the use of gamma rays for soil moisture estimation would "require additional refinements". For sure, this would be capabilities of a spectrometer, since total gamma rays are not well correlated as this study and as other literature has shown. Are spectrometric capabilities possible in future improvements of this device?
9. Fig 8 shows only a short period of gamma data, shorter than the presented neutron data. So, is the measurement of three particles not simultaneous during the full period? If yes: isn't this the main key or if no, why not showing everything?  

Specific comments

• L32: replace "correct" by "reliable" or "accurate".
• L47, L51: the correlation is "negative" rather than "inverse".
• L45-46: the citations list appears random, at least try to briefly explain which author found what and to what degree of certainty (not simply "good performance"). Use citations to concretely support your statements.
• L48: "favourable" compared to what?
• L47: try to cite literature that actually decribe the physical process of neutron-hydrogen interactions.
• L51: replace "noise" by "nuisance"
• L54: rephrase or reorder: "1979" is not "decades later" than 1966, 2001, and 2021.
• L60: add Köhli et al 2015 for up-to-date literature on the footprint.
• L63: what us "water management and assessment" and how do those cited papers contribute to it? Add also Evans et al 2016 for a reference to Cosmos-UK with regards to your mentioned national networks.
• L84: Use concrete and scientific language: how are scintillators "safer" than He-3?
• L85: Use concrete and scientific language: how are scintillators "relatively compact" compared to He-3 tubes?
• L87: Use concrete and scientific language: what is a "special property"?
• L104: "easily detect", ok it is easy, but how exactly is the detection mechanism?
• L106: this would be a good place to reference Fig 1a.
• L116-118: rephrase, as the paragraph is very unspecific and it is not clear what value the citations have provided. Please try to elaborate more on it, or remove the sentence. At least add "among others" to indicate an incomplete list.
• L118: rephrase "current state of the art" (see minor concerns above), as incoming correction does not account for rigidity (L125, Hawdon et al 2014), humidity correction ignores higher-mode dependency on soil moisture (L126, Köhli et al 2021), constant N0 ignore biomass dependency (Baatz et al 2014), and the neutron-moisture relationship might become invalid under dry conditions (eq 5, Köhli et al 2021). Not all of the approaches must be used here, as some have not been established yet, but the present approach should not be called "current ..."
• L130: note that it is risky to take mean values as references since they would change with every change of measurement period and are not transferrable to other places and times. Consider using constant values, e.g. from Bogena et al 2022.
• L136: since you refer to data processing procedures used at various sites in Europe, it would be a good place to cite Bogena et al 2022.
• L148, rephrase "has been shown to be an alternative", since Stevanato et al may have provided first evidence, but final proof is still missing. Your new sensor could certainly contribute to collecting more data to better investigate this hypothesis in the future.
• L149: be more careful here, you are presenting a new measurement method, but you cannot claim that this methodological approach actually works. Please discuss potential effects of atmospheric temperature, and suggest further research as this is out of scope here.
• L157: do you mean air temperature instead of air humidity?
• L60: remove second appearance of the link.
• L171: "this energy region", be more specific please, which region exactly?
• L176: do you mean "total signal" instead of "these signals"?
• L198: in the discussion about meter-scale influences on neighboring sensors, add Schrön et al 2018 (GI) and Patrignani et al 2021 (Frontiers) who discussed exactly that.
• Fig 2: add distances, meter scales, and more of the surrounding to better support your discussion on nearby influences.
• L195: do you mean "long-term obervations and real-time data transmission"?
• L233: please rephrase, relative to Lab-C?
• L235: "can be considered reliable", at this point of the text no mesures have been shown. There are measures in the Fig 4 legend, though, which should be mentioned in the text before claiming something reliable.
• L253: Same as above, please mention and discuss RMSE before calling something reliable.
• L287: consider adding Jakobi et al 2018.
• L300: the improvement seems to be only during the second event, not for all "precipitation events".
• Fig 8: what is the cause of the spike of the correlation plot? Can you add measures such as R squared?
• L331: put concrete measures and uncertainties rather than just "performed well".

Cosmetics

• Fig 3: use site names as panel titles instead of in a single legend. Color-blind people cannot identify which panel corresponds to what site.
• Fig 4: rearrange or relabel, such that a,b are top and c,d are bottom (which is convention). Also, please put a comprehensive ylabel for c,d. In c,d, the two sensors are nit distinguishable for color-blind people, black/white displays or prints, etc. Use HCL color space and colors with different luminosity.
• Fig 5: use crosses instead of circles to better indicate the exact date and value of the data point. Also consider printing errorbars.