A muographic study of a scoria cone from 11 directions using nuclear emulsion cloud chambers

Miyamoto, Seigo; Nagahara, Shogo; Morishima, Kunihiro; Nakano, Toshiyuki; Koyama, Masato; Suzuki, Yusuke

doi:https://doi.org/10.5194/gi-11-127-2022

Articles | Volume 11, issue 1

https://doi.org/10.5194/gi-11-127-2022

© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/gi-11-127-2022

© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 11, issue 1

Research article

|

22 Mar 2022

Research article |

| 22 Mar 2022

A muographic study of a scoria cone from 11 directions using nuclear emulsion cloud chambers

Seigo Miyamoto, Shogo Nagahara, Kunihiro Morishima, Toshiyuki Nakano, Masato Koyama, and Yusuke Suzuki

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Final revised paper (published on 22 Mar 2022)
Preprint (discussion started on 20 Dec 2021)

Interactive discussion

Status: closed

RC1: 'Comment on gi-2021-35', Anonymous Referee #1, 14 Jan 2022

This article concerns a study of the cone of the Izu–Omuroyama scoria volcano (Japan) using the muon radiography technique.

The authors installed nuclear emulsion detectors and performed a measurement campaign from 11 different directions.

They reported the detector design and installation and the data analysis procedure. So they produced the map density from everyone

the indications and discussed the results obtained.The article is detailed and methodologically correct.

It is fluent enough with good English. The results obtained are very interesting, also considering the possible developments on a 3D analysis of the volcanic cone.

I have just a few small observations to discuss before publication:

Lines 93-94: “An ECC detector can measure the momentum of the charged particle by detecting deflection angles caused by multiple Coulomb scattering.”â¨

In my opinion a ECC doesn’t measure the momentum. It can provide a statistical information of the momentum of the muons, as correctly described in the section 4.2

Line 97: Please describe better and/or give a reference about the formula (1)

Line 117 “at 4 ka”

It is not clear to me which is the age.

Lines 1169-170 “we needed to add time information to the ECC”

It is not very clear the meaning of this sentence. Please rephrase.

Line 232: please provide the units of the errors the angles.

Is the absolute azimuth coordinates provided directly by the instrument ?

Which are the angles measured with the FOG and which with the digital leveler ?

â¨

Lines 310-311: How do you evaluate the filtering efficiency ? It is not described and no reference is given.

Lines 315-316: how many are the candidate tracks ?

Lines 444-445: “There were also 4%–7% in each detector site except the forward directions at the SE and NNE site “

This sentence is not clear to me.

Citation: https://doi.org/10.5194/gi-2021-35-RC1
RC2:
'Comment on gi-2021-35', Anonymous Referee #2, 14 Jan 2022

The article submitted is of very high quality.

It is written in good English and reads well.

The methodology is rigorous and well established, and the presentation of results is fair.

There is only one aspect that needs a clarification. Because each ECC stack belongs to a different observation point, the reader is left with the suspect that there are possible systematic effects in data that may mimic interesting signals. In order to make the statements stronger, I would suggest to publish/check the efficiency maps (or fill factor maps) not only as functions of slope/angle, but also of position in the film. Indeed, local drops of efficiency or background increases in certain areas of the films may add systematic effects. While they have probably been correctly accounted for, at least on average (pages 24,25,26,27), the text does not clarify enough the treatment of position-dependent performance variations of the emulsion films.

I understand this revision requires further editing work, but the data should already be available to them; I think it is in the interest of the authors to provide the strongest possible evidence for the signals observed.

All the rest of the manuscript is fine.

Citation: https://doi.org/10.5194/gi-2021-35-RC2
- AC3: 'Reply on RC2', Seigo Miyamoto, 02 Feb 2022
  
  Sorry, I added appendix A in the previous reply, but I realized that the discussion about noise tracks and how they affect the result is not enough.
  I've added Figure 16 about the position dependency of selected tracks and mentioned about the possibility that the fake tracks affect the result in the Appendix.
  
  Citation: https://doi.org/10.5194/gi-2021-35-AC3
AC1: 'Comment on gi-2021-35', Seigo Miyamoto, 27 Jan 2022

First of all, thank you for both of referees, for your careful reading of our manuscript and giving us some good comments.

----------------
To the referee 1,
> Lines 93-94: “An ECC detector can measure the momentum of the charged particle by detecting deflection angles caused by multiple Coulomb scattering.”â¨
> In my opinion a ECC doesn’t measure the momentum. It can provide a statistical information of the momentum of the muons, as correctly described in the section 4.2

Maybe I've wrote some unclear text.
Although we used the statistical momentum filtering in this study, an ECC detector can measure the momentum of a high-energy charged particle, one by one, as shown in the previous studies (e.g., Agafonova et al., 2012).
I've changed the texts (Line 93-95).
"An ECC detector can measure the momentum of the charged particles, one by one, by detecting deflection angles caused by multiple Coulomb scattering (Agafonova et al., 2012)."

> Line 97: Please describe better  and/or give a reference about the formula (1)

I've added the following reference "Review of Particle Physics", M. Tanabashi et al. (Particle Data Group)
Phys. Rev. D 98, 030001, 2018.
And I also gave the detailed description about some related equations of the reference (Line 95-97).

> Line 117 “at 4 ka”

I've changed from "at 4 ka" to "about 4,000 years ago".

> Lines 169-170 “we needed to add time information to the ECC”

I've changed the sentenses:

Before:
Given that there is no temporal resolution in emulsion films, we needed to add time information to the ECC. In previous muographic studies using emulsion films, researchers have used emulsion films with a different alignment during the muon observations and standby (e.g., Tanaka et al., 2007).

After :
Given that there is no temporal resolution in emulsion films, the ordinary ECC detectors can't distinguish whether the cosmic-ray tracks pass the ECC during muographic observation or transportation and standby. Thus we also add a similar gimmick as previous muographic studies using emulsion films. The researchers have used emulsion films with a different alignment during the muon observations and standby (e.g., Tanaka et al., 2007).

> Line 232: please provide the units of the errors the angles.
> Is  the absolute azimuth  coordinates provided directly by the instrument ?
> Which are the angles measured with the FOG and which with the digital leveler ?

I added some additional information to the corresponding texts.

"Measure the attitude of the outer box (i.e., the yaw [azimuth], roll, and pitch). The yaw was measured with a fiber optic gyro (Japan Aviation Electronics Industry Ltd.; model FOG JM7711; Watanabe et al., 2000), and roll and pitch were measured by the digital leveler. The typical errors on the yaw, roll, and pitch are 8.7 x 10^-3, 1.0x10^-3, and 1.0x10^-3 radians, respectively."

> Lines 310-311: How do you evaluate the filtering efficiency ? It is not described and no reference is given.

I added the following sentence:
This figure was derived from a simple simulation in which the interaction of charged particles inside the ECC was assumed to be multiple Coulomb scattering only, and the scattering angle was approximated by a Gaussian distribution.

> Lines 315-316: how many are the candidate tracks ?

In the end of section 4.1, "... and 1.7 x 10^7 tracks in an entire ECC were reconstructed."

> Lines 444-445: "There were also 4%–7% in each detector  site except the forward directions at the SE and NNE site (Fig. 14)."
> This sentence is not clear to me.

I've modified.

Before:
There were also 4%–7% in each detector  site except the forward directions at the SE and NNE site (Fig. 14).

After:
An example of observed/expected muon flux ratio angular distribution of the site N is shown in Fig. 14. As can be seen in this figure, in each detector site, the inhomogeneous distribution of the observed/expected muon flux ratio exists. The deviations were 4%–7% except the forward directions at the site SE and NNE.

---------------------
To the referee 2,

> There is only one aspect that needs a clarification. ...........

> ..... the text does not clarify enough the treatment of position-dependent performance variations of the emulsion films.

I've added a new appendix and you can see the figure (Fig. 15) of position distribution of fill factor there.

Citation: https://doi.org/10.5194/gi-2021-35-AC1
AC2: 'maybe my reply about RC2 was not enough', Seigo Miyamoto, 28 Jan 2022

Maybe my previous reply about RC2 was not enough, I've just realized.
I will reply again in a few days.

Citation: https://doi.org/10.5194/gi-2021-35-AC2

Peer review completion

AR: Author's response | RR: Referee report | ED: Editor decision

AR by Seigo Miyamoto on behalf of the Authors (07 Feb 2022) Author's response Author's tracked changes Manuscript

ED: Publish as is (16 Feb 2022) by Ralf Srama

Short summary

In recent years, imaging of density inside volcanoes using cosmic-ray muons has been studied. In some previous studies, observations were conducted in 2 or 3 directions to obtain 3D resolution. For higher resolution, we tried to observe a volcano from 11 directions using special photographic films. The observation and analytical techniques developed in this study may be applied to other volcanoes and large objects. Reconstructing 3D images of the volcano is in progress using the obtained data.