Characterization of kHz Repetition Rate Laser-Driven Electron Beams by an Inhomogeneous Field Dipole Magnet Spectrometer

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Please see the referee report.

Comments for author File: Comments.pdf

Author Response

Dear reviewer,

thank you for the rigorous reading of the paper, pointing us on unclearness, and necessity to improvement its readability. The major questions you asked, are very fundamental for this work, and we appreciate that you have brought to our attention, that additional explanation is needed.

The answers are given as replies and indications, where the relevant changes in the text have been applied.

Major question:
#1 It seems that there is no problem based on the description of Line158-172 and Fig. 6, but I am afraid my understanding is wrong, so please answer the following questions.
Divergence of the electron beam occurs not only in the x ‐ direction but also in the y ‐ direction. So the consideration of trajectory need to think y-direction as well as the x-direction not only displacement of position but also direction of the motion. Also, consideration of non-uniformity of the magnetic field in the y-direction is needed. Did you this consideration taken into account in the

calculation?

 

 

Thank you for the question. Yes, the standard procedure for evaluation (mentioned in the manuscript at line 185) is the definition of the beam pointing and the calculation of the exact calibration curve for these specific x and y pointing values. However, the vertical magnetic field inhomogeneity within the electron beam size at the vertical plane of the magnet (cca 3 mm) is below 5%, so it is not discussed in the paper in detail.

 

Minor change in the text is introduced for clarity

 

Line 156, added in the text: generation of an individual calibration curve for specific vertical and horizontal beam pointing values

#2 Does the difference in pulse width between LPA and LINAC affect the evaluation of LANEX?

 

The LANEX has been selected as the most suitable detector for the high intensity beams, as it has a high saturation level, and is considered to be less sensitive to intensity saturation effects by the LWFA community (reference [45]). For this reason, some groups are justifying a use of continuous sources for the calibration(e.g. same reference [45]). The charge per pulse is below the LANEX saturation level for both sources used in our work.

 

Stated at line 460: Our calibration assumes the same response of the LANEX Fast Back screen to the LINAC and LPA electron beams, which have different time structure.

 

Also, the authors described that the emission time of LANEX is less than 1 ms (Line140-142) and open time of the camera was set at sub-ms. It seems that the timing jitter of the camera makes an error in the accuracy of the data for sub-ms shutter time. Did you make such an evaluation?

 

 

The dose measurement is performed for acquisition time identical to the calibration with the medical linac. Single shot acquisition (<1 ms exposure) is done by setting camera exposure to 990 µs, and the camera jitter is less than 1 µs.

 

 

Clarified at lines 111, 123

 

 

 

 

It seems some minor QA and modifications are necessary. Key points are listed:

1. Abstract
   #1 It is not in the standard form as an abstract. You need to make the point as short as possible (e.g. Description from line 28 to 29 are unnecessary and start with "We demonstrate..." is better). #2 Line38 It does not specify what the 10% is for. It must be clarify.

 

Changed according to the suggestion

 

1. Introduction
   There is generally no problem in the section of introduction. However, line76 and later should be revised.

#3 Line76: "In this work..." should follow the presentation of the problem. First, it should describe the author's identified difficulty in evaluating the energy-resolved divergence angle with conventional spectrometers, in that the divergence angle of the electron beam is wide and error is not ignorable. After this, describe "In this work..." is better.

#4 Line77: “is shown” is unsuitable. For example, “is developed” is better. #5 Line88: Line break seems unnecessary.

 

Changed according to the suggestion

 

1. Materials and methods
   There are some unclear points. Responses and/or corrections are required.

#6 The section title "Design of the EBDS" or “Feature of the EBDS” is more appropriate because it mainly describes the design in the section.

 

Changed according to the suggestion

 

#7 Line125: The Basler acA2040-25gm has a performance of 25 frame per seconds which does not seem to fully support 1 kHz rep. rate. Is this enough?

 

In the described case it can be operated in “integration mode” with 20-100 ms opening time, or resolving a single beam shot with 10 Hz repetition rate, (depends on the synchronization trigger, it can be up to 25 Hz as you mentioned)

 

#8 Line141: “sub-ms opening time” should also be described in the performance description in Line from 125 to127.

 

Corrected to the exact number.

#9 Fig. 2: In Section 3, it seems the magnetic field distribution of the actual magnet is measured through a Gaussmeter. It seems to be possible to evaluate to 3D mapping the actual magnetic field of the analyze magnet by using this tool. Have you obtained the 3D data mapping of the magnetic field by this Gaussmeter and compared it with the calculated value of the magnet?

 

No, we measured the magnetic field in several points, set with an accuracy of 1 mm, to verify the consistency of the experimental data and simulation results.

 

#10 Line212: At first, it is necessary to explain that the dosimetry must be considered in order to calibrate the sensitivity of EBDS by using the dosimeter.

 

Changed according to the suggestion

 

#11 Section 2.2: It seems section 2.2 moved to section 3 is better.

 

Changed according to the suggestion

 

1. Results
   There are also some unclear points. Responses and/or corrections are required.

#12 Title: “Calibration of the EBDS” is better

 

Changed according to the suggestion

#13 What is the position accuracy of the EBDS at the calibration? Also, did you use an assisting tool for positioning of EBDS (e.g. in X-ray CT scanner, laser pointer is installed for checking the position of X-ray) in reference medical linac?

 

Yes, laser pointing system is a basic feature of the used Elekta LINAC system, and it has been used for the positioning. The estimated pointing accuracy achieved with this system is about 1 mm.

#14 Figs. 10 and 11: In Figs. 10(b), 10(d), and 11(b), it would be more appropriate to show not only linear-linear scale graph but also the linear-logarithm scale.

 

The EBDS 25 Hz camera has a dynamic range of about one - two orders of magnitude depending on the experimental background, so we believe the linear scale is sufficient to represent measured data. Nevertheless, some minor changes have been introduced to improve the general clarity.

 

1. Discussion
   #15 Title: “Summary” is better.

Changed according to the suggestion

 

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The paper is about the design, calibration and implementation of an electron spectrometer, the main diagnostic for LWFA experiments to characterize the parameters of the generated electron beam. This diagnostic is commonly built with magnets, LANEX screens, and an imaging system as described in this paper. The paper specifically describes the electron spectrometer built for the ALFA beamline at ELI and describes, in depth, the calibration and analysis process. It is common for facilities, specially facilities with many collaborators such as user facilities, to publish detailed information about their diagnostic setup. 

In this case, ALFA beamline operates with 10s of mJ and at a high rep rate (relatively new regime of operation for LWFA and its applications) requiring an electron spectrometer capable of detecting and resolving multi MeV to tens of MeV electron beam in a “continuous” mode. The diagnostic measures energy, profile, charge and dose and its design also takes into consideration different initial beam pointings. 

The authors describe the design and geometry of a wide-gap dipole magnet spectrometer (to avoid laser damage) with inhomogeneous magnetic field, the effort and result of calibration with a known medical source, and initial result of experiments at ALFA beamline. They provide details such as conversion of the real magnetic field measurements to full field map, particle trajectory (various energy, divergence and beam pointings) within such a 3D field map (SIMION), Monte Carlo simulations (FLUKA) for electron beam propagation through different components of the setup and for deposited dose calculations, detail of the calibration experiments proving the reliability and trustworthiness of the measurements and their precision. 

This is worth publishing since it provides description of the setup and accuracy of the measurement at different energies for potential collaborators and users of the beamline. Further, the publication can be educational for academic students who may want to understand the design and calibration process and challenges or may need to build similar diagnostics for their own experiments. The authors have done a good job describing the steps. I did notice several editorial errors, for example the EBDS is spelled EDBS in many places and on line 125 shutter is misspelled (amongst a few others).

Author Response

Referee 2

 

The paper is about the design, calibration and implementation of an electron spectrometer, the main diagnostic for LWFA experiments to characterize the parameters of the generated electron beam. This diagnostic is commonly built with magnets, LANEX screens, and an imaging system as described in this paper. The paper specifically describes the electron spectrometer built for the ALFA beamline at ELI and describes, in depth, the calibration and analysis process. It is common for facilities, specially facilities with many collaborators such as user facilities, to publish detailed information about their diagnostic setup. 

In this case, ALFA beamline operates with 10s of mJ and at a high rep rate (relatively new regime of operation for LWFA and its applications) requiring an electron spectrometer capable of detecting and resolving multi MeV to tens of MeV electron beam in a “continuous” mode. The diagnostic measures energy, profile, charge and dose and its design also takes into consideration different initial beam pointings. 

The authors describe the design and geometry of a wide-gap dipole magnet spectrometer (to avoid laser damage) with inhomogeneous magnetic field, the effort and result of calibration with a known medical source, and initial result of experiments at ALFA beamline. They provide details such as conversion of the real magnetic field measurements to full field map, particle trajectory (various energy, divergence and beam pointings) within such a 3D field map (SIMION), Monte Carlo simulations (FLUKA) for electron beam propagation through different components of the setup and for deposited dose calculations, detail of the calibration experiments proving the reliability and trustworthiness of the measurements and their precision. 

This is worth publishing since it provides description of the setup and accuracy of the measurement at different energies for potential collaborators and users of the beamline. Further, the publication can be educational for academic students who may want to understand the design and calibration process and challenges or may need to build similar diagnostics for their own experiments. The authors have done a good job describing the steps. I did notice several editorial errors, for example the EBDS is spelled EDBS in many places and on line 125 shutter is misspelled (amongst a few others).

 

 

 

Dear reviewer, we appreciate your effort in reviewing the manuscript and pointing us to misspells and the necessity to make additional technical proofreading of the text.

Your opinion and positive evaluation are extremely valuable to us.

The following changes have been implemented:

• EDBS misspelled word corrected to EBDS (at all places)
• Shutter misspell corrected
• Spelling revised

 

 

Kind regards,

Illia Zymak on behalf of all co-authors

                                                                                                                                                                                                      

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

This paper describes the development of an apparatus for the characterisation of sub 50 MeV electron beams produced with KHz Terawatt laser pulses in a gas target. Due to the high divergence, spacial uniformity, wide energy bandwidth, irreproducibility and pointing instability, of the electron beams produced with this parameters, its characterisation is challenging. The authors described their effort to mitigate these problems by adding a vertical slit and increasing the gap between the permanent magnets of the energy analyser dipole. This allows to measure the electron spectra with approximately 10% accuracy  for energies up to 20 MeV. Additionally the authors have calibrated their apparatus for being able to measure the radiation dose delivered by the plasma accelerator. They conclude using the calibrated apparatus to characterising an electron beam generated by laser-plasma accelerator.

 

 

I found this paper confusing, difficult to read and unnecessarily long. I my opinion the paper should be reviewed by the authors and resubmitted after being simplified and taking into account the following.

 

In lines 55 to 49 the authors mention a breakdown limit for radio frequency accelerator as 100 MeV/m. Although this constrains HEP acceleration, it is hardly a limit for medical a LINAC. Of course LWFA overcome overcome RF accelerators in compactness bringing manny other new problems far more difficult to solve that finding a few square meters in an hospital or tech company.

 

In this introductory paragraph the authors should at least mention FLASH therapy and its relation with the present work (quoting e.g.https://doi.org/10.3390/app13085021)

 

In lines 60 to 61 the authors mention the references [16 and [17] as examples of proven LASER-plasma accelerators. In fact LWFA is a well proven concept proposed by Tajima and Dawson in last century with first important results in 2004 with significant theoretical, numerical and experimental work developed since then (almost all ignored by the authors). The reference [16] from year 2000 cannot be quoted as one of the most relevant citations for the LWFA. Reference [17] is also not representative of the developments of laser driven accelerators, specially when using short (few fs) laser pulses. Ref. [18] is not representative of the wide effort to develop LWFA radiation sources.

 

In the paragraph from lines 69 to 75, the paper [doi.org/10.1007/s00340-021-07610-z] should be included since they did similar dosimetric work relevant for this paper context.

 

The authors should clarify the meaning of the sentence in lines 149-150. 

 

In line 152, the authors mention that a vertical line integration is the first step on their data treatment. But, at least, in the case the dipole is not centred with the beam axis the deflection on the beam changes not only with electron energy but also with your Y coordinate. Therefore a vertical integration will potentially introduce a distortion in the spectra. Can you clarify?

 

Sentence in lines 199 and 200 should be clarified, for example what are “irradiation components”?

 

The figure 6 in page 7 shows a FLUKA simulation with the electron beam (after filtering by the slit collimator) being bend by the finge field of the magnet. The authors should explain or at least mention the apparent generation of electrons in the filter (why the fluence is higher immediately after the filter) and specially in and immediately after the slit. The authors should mention int he text mechanism that focus the electron beam in the Y direction (figure 7 b) (even if it seems almost obvious). The author should explain the apparently (to) rapid decrease in the beam fluence after the slit in figure 7-a. The rapid decrease after the slit could be expected if the “new” secondary electrons generated in the slit suffer a Colombian explosion. However after being deflected by the magnet the beam keeps decreasing in fluence without an apparent increase in diameter. Moreover, the beam is apparently focusing in the Y direction (according to figure 7-b) which lead me to expect a corresponding increase in fluence and not a decrease. Can you clarify? 

 

The sentence in lines 348 to 351 is not clear. Can you clarify from were you think the systematic error come from. Does the LINAC energy has an error bar? Can you clarify the meaning of “output beam collimator” (line 353)? What in your opinion is the effect of changing from a 2 mm slit to a 4 mm diamter collimator for the discrepancy in the graphic of figure 8? 

 

As for the dose calibration there is a difference between the setup used with the LINAC and the laser. In the later there is aluminium slit that blocks a significant fraction of the electron beam (if not most of it). The blocking of those electrons with a 5 mm aluminium plate must result in the emission of additional x-rays with a broad spectrum extending to high energy (MeV). Can you estimate the effect of the slit plate in your dose calibration results? 

 

In line 135 you mention the distance between the nozzle and collimator but you did not provide the actual distance. This value is important to understand you images in figures 10 and 11. You should provide that distance.

 

In the caption of figure 10 you should mention that in a) the dipole have been removed. Figures 10-1, 10-b ad 11-z would be clear if the have same x dimensions and color bars. 

 

It is not clear how the image in figure 12 demonstrates, as you say in lines 423-424, the optimisation of the beam alignment. Moreover the image does not seem to resemble qualitatively the image in figure 6-c. You don’t explain how you obtained the image in figure 12. Is it a single shot or also an average of 10 shots? Did you moved the dipole in the sem way as in figure 6-c? Is it possible to have the same X and Y frames has in figure 10-a, 10-c and 11-a? Can you provide a meaningful color bar (e.g. the same or related color bars to figures 10-a, 10-c and 11-a)

 

In line 435 you mention your apparatus was optimised for high-vacuum. In what consisted the optimisation for specifically high-vacuum? 

 

From line 442, you mention that the wide-gap dipole allows a 380 mrad beam divergence when not inserted. Would not a zero-gap dipole allow the same divergence when not inserted? 

 

Also from line 442, you mention the wide -gap prevent laser damage? Can you clarify? Having into account you mention the slit plate (which sits before) is already in a safe distance? 

 

The text seem to make more sense if the period in line 460 is not a new paragraph too. 

 

The sentence in line 467 does not seem to make sense. Same in line 471. 

Comments on the Quality of English Language

All comments, including English language related, we made in the repor above. 

Author Response

Referee 3

 

This paper describes the development of an apparatus for the characterisation of sub 50 MeV electron beams produced with KHz Terawatt laser pulses in a gas target. Due to the high divergence, spacial uniformity, wide energy bandwidth, irreproducibility and pointing instability, of the electron beams produced with this parameters, its characterisation is challenging. The authors described their effort to mitigate these problems by adding a vertical slit and increasing the gap between the permanent magnets of the energy analyser dipole. This allows to measure the electron spectra with approximately 10% accuracy  for energies up to 20 MeV. Additionally the authors have calibrated their apparatus for being able to measure the radiation dose delivered by the plasma accelerator. They conclude using the calibrated apparatus to characterising an electron beam generated by laser-plasma accelerator.

 

 

I found this paper confusing, difficult to read and unnecessarily long. I my opinion the paper should be reviewed by the authors and resubmitted after being simplified and taking into account the following.

 

 

Dear referee, thank you for reading and critical analysis of the manuscript. We highly appreciate your work on improvement of the clarity and structure of the paper. The structure of the paper has been reworked, also the text has been clarified, shortened and proof readed. We also have implemented all your valuable suggestions and comments.

More detailed discussion of changes is given in the further list.

 

In lines 55 to 49 the authors mention a breakdown limit for radio frequency accelerator as 100 MeV/m. Although this constrains HEP acceleration, it is hardly a limit for medical a LINAC. Of course LWFA overcome overcome RF accelerators in compactness bringing manny other new problems far more difficult to solve that finding a few square meters in an hospital or tech company.

 

We thank the referee for his comment. We removed the sentence “This technology limitation leads to a virtual dead-end in terms of compactness efforts and limits their construction and maintenance cost competitiveness, thus making them unavailable for many small laboratories and medical institutions.”

 

In this introductory paragraph the authors should at least mention FLASH therapy and its relation with the present work (quoting e.g.https://doi.org/10.3390/app13085021)

 

We thank the referee for his comment.

 

At line 58 : We added the following sentence “, in view of reaching the beam parameters required for FLASH therapy.” 

 

 

In lines 60 to 61 the authors mention the references [16 and [17] as examples of proven LASER-plasma accelerators. In fact LWFA is a well proven concept proposed by Tajima and Dawson in last century with first important results in 2004 with significant theoretical, numerical and experimental work developed since then (almost all ignored by the authors). The reference [16] from year 2000 cannot be quoted as one of the most relevant citations for the LWFA. Reference [17] is also not representative of the developments of laser driven accelerators, specially when using short (few fs) laser pulses. Ref. [18] is not representative of the wide effort to develop LWFA radiation sources.

 

We thank the referee for his comment. We have changed the references mentioned in the text.

 

In the paragraph from lines 69 to 75, the paper [doi.org/10.1007/s00340-021-07610-z] should be included since they did similar dosimetric work relevant for this paper context.

 

We thank the referee for his comment. We have included the recommended citation.

 

 

The authors should clarify the meaning of the sentence in lines 149-150. 

 

Thank you for the suggestion. The sentence has been reformulated, with more clear reference to the section where it is demonstrated using the simulation results.

 

Line 131: changed to “The energy of the electrons is measured with respect to the furthest edge of the aperture, as described using simulation results in sections 2.1.2 and 2.1.3”

 

 

In line 152, the authors mention that vertical line integration is the first step on their data treatment. But, at least, in the case the dipole is not centred with the beam axis the deflection on the beam changes not only with electron energy but also with your Y coordinate. Therefore a vertical integration will potentially introduce a distortion in the spectra. Can you clarify?

 

Thank you for the question. Yes, the standard procedure for evaluation is the definition of the beam pointing and the calculation of the exact calibration curve for these specific x and y pointing values (sections 2.1.2 and 2.1.3). However, the vertical magnetic field inhomogeneity within the electron beam size (cca 3 mm at magnet entrance) is below 5%, which is significantly lower than horizontal pointing effects.

Minor change in the text is introduced to avoid further confusion.

 

Line 156, added in the text: vertical and horizontal beam pointing.

 

Sentence in lines 199 and 200 should be clarified, for example, what are “irradiation components”?

 

Minor changes were introduced, to remove the unclear formulation.

 

Line 170: reformulated for clarity to “irradiation experiments”

 

The figure 6 in page 7 shows a FLUKA simulation with the electron beam (after filtering by the slit collimator) being bend by the finge field of the magnet. The authors should explain or at least mention the apparent generation of electrons in the filter (why the fluence is higher immediately after the filter) and specially in and immediately after the slit. The authors should mention int he text mechanism that focus the electron beam in the Y direction (figure 7 b) (even if it seems almost obvious). The author should explain the apparently (to) rapid decrease in the beam fluence after the slit in figure 7-a. The rapid decrease after the slit could be expected if the “new” secondary electrons generated in the slit suffer a Colombian explosion. However after being deflected by the magnet the beam keeps decreasing in fluence without an apparent increase in diameter. Moreover, the beam is apparently focusing in the Y direction (according to figure 7-b) which lead me to expect a corresponding increase in fluence and not a decrease. Can you clarify? 

 

Thank you for finding a wrong visualization settings.

The figure presents an example simulation of the setup geometry for the 3MeV electron beams to evaluate possible focusing effects and the contribution of secondary and scattered electrons to the total LANEX luminosity.

 

Different projections of integration slices are used in fig a and b, which lead to wrong beam intensity visualization.

 

As suggested, the integration range is changed in Figure 7b to avoid a misinterpretation. Also, statistics of the Monte Carlo simulation is significantly improved, to maintain the previous accuracy for the smaller integration area.

 

The sentence in lines 348 to 351 is not clear. Can you clarify from were you think the systematic error come from. Does the LINAC energy has an error bar? Can you clarify the meaning of “output beam collimator” (line 353)? What in your opinion is the effect of changing from a 2 mm slit to a 4 mm diamter collimator for the discrepancy in the graphic of figure 8? 

 

Additional explanation is added at lines 302 – 310, also figure 8 is changed.

 

As for the dose calibration there is a difference between the setup used with the LINAC and the laser. In the later there is aluminum slit that blocks a significant fraction of the electron beam (if not most of it). The blocking of those electrons with a 5 mm aluminium plate must result in the emission of additional x-rays with a broad spectrum extending to high energy (MeV). Can you estimate the effect of the slit plate in your dose calibration results? 

 

We agree that additional explanation may improve the clear description of the model.

Additional simulations have been performed to quantify described effect. The fluence of the X-rays generated both in the slit and the screen itself is below 1% of the electron fluence.

However, secondary electrons will be generated and primary beam will be scattered by the slit. This effect can contribute up to 1% of the electron beam fluence, an can be observed in figure 6a, c, and in the two figures below (in logarithmic scale).

 

In line 135 you mention the distance between the nozzle and collimator but you did not provide the actual distance. This value is important to understand you images in figures 10 and 11. You should provide that distance.

 

The exact number is already listed at lines 172 – 175.

The additional reference at line 119 is added, to remove unclearness.

 

 

In the caption of figure 10 you should mention that in a) the dipole have been removed. Figures 10-1, 10-b ad 11-z would be clear if the have same x dimensions and color bars. 

 

Thank you for the suggestion. Proposed improvements has been introduced.

 

It is not clear how the image in figure 12 demonstrates, as you say in lines 423-424, the optimisation of the beam alignment. Moreover the image does not seem to resemble qualitatively the image in figure 6-c. You don’t explain how you obtained the image in figure 12. Is it a single shot or also an average of 10 shots? Did you moved the dipole in the sem way as in figure 6-c? Is it possible to have the same X and Y frames has in figure 10-a, 10-c and 11-a? Can you provide a meaningful color bar (e.g. the same or related color bars to figures 10-a, 10-c and 11-a)

 

 

Thank you for pointing us to the unclearness. The paragraph has been rewritten.

 

In line 435 you mention your apparatus was optimised for high-vacuum. In what consisted the optimisation for specifically high-vacuum? 

 

Such optimization is a standard procedure for the in-vacumm components at ELI Beamlines, required to increase the lifecyle of systems. It includes the use of ultra-high vacuum-compatible materials, minimizing laser–material interaction with materials that potentially may release VOCs, removing air-pockets (or adding outgassing channels), use of materials that can be cleaned and baked-up and than final RGA analysis of the new component.

 

From line 442, you mention that the wide-gap dipole allows a 380 mrad beam divergence when not inserted. Would not a zero-gap dipole allow the same divergence when not inserted? 

 

EBDS includes more diagnostic functions than energy measurements.  Different modes have different acceptance angles. The system acceptance angle with the removed magnet is important for beam profile and intensity measurements.

 

Clarified at line 395: “… compare to 380 mrad for the extracted magnet (limited by screen size).”

 

Also from line 442, you mention the wide -gap prevent laser damage? Can you clarify? Having into account you mention the slit plate (which sits before) is already in a safe distance? 

 

The statement is removed from the manuscript to avoid unclearness.

 

The text seem to make more sense if the period in line 460 is not a new paragraph too. 

 

Thank you for the suggestion, the modification has been implemented.

 

The sentence in line 467 does not seem to make sense. Same in line 471. 

 

Sentences has been simplified and clarified

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The quality of the revised manuscript has improved significantly. In addition, the author's response seems to clear my question sufficiently. I would recommend the manuscript is suitable for publication in Photonics.

Author Response

Reply to Reviewer #1

 

Dear reviewer, on behalf of the co-authors of the manuscript, I thank you for your efforts, which resulted in improvement of the readability and scientific quality of our work.

 

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

In face of the improvements made by the authors I recommend the paper for publication, after a minor correction. 

By Lines 188-191 the authors should briefly add on or more reasons for the non negligible discrepancy between the curves of the graphic in figure 5. 

 

Also correct indentation of references. 

 

Author Response

Reply to Reviewer #3

 

Dear reviewer, we appreciate your efforts, which resulted in an improvement of the readability and scientific quality of our work.

 

Your suggestions for the second round of the revision process have been implemented.

 

 

Implemented changes:

 

At line 193, According to your comment we add “… due to the scattering of primary electrons and the production of secondary particles during the beam propagation in the medium.”

 

The alignment of the list of references has been revised.

Author Response File: Author Response.pdf