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Highlights from the Telescope Array Experiments

by Hiroyuki Sagawa

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Submission summary

Authors (as registered SciPost users): Hiroyuki Sagawa
Submission information
Preprint Link:  (pdf)
Date submitted: 2023-03-16 11:30
Submitted by: Sagawa, Hiroyuki
Submitted to: SciPost Physics Proceedings
Proceedings issue: 21st International Symposium on Very High Energy Cosmic Ray Interactions (ISVHECRI2022)
Ontological classification
Academic field: Physics
  • Gravitation, Cosmology and Astroparticle Physics
Approach: Observational


The Telescope Array (TA) is the largest hybrid cosmic ray detector in the Northern Hemisphere, which observes primary particles in the energy range from 2 PeV to 100 EeV. The main TA detector consists of 507 plastic scintillation counters on a 1.2-km spacing square grid and fluorescence detectors at three stations overlooking the sky above the surface detector array. The TA Low energy Extension (TALE) hybrid detectors, which consists of ten fluorescence telescopes, and 80 infill surface detectors with 400-m and 600-m spacing, has continued to provide stable observations since its construction completion in 2018. The TAx4, a plan to quadruple the detection area of TA is also ongoing. About half of the planned detectors have been deployed, and the current TAx4 continues to operate stably as a hybrid detector. I review the present status of the TA experiment and the recent results on the cosmic-ray anisotropy, mass composition and energy spectrum.

Current status:
Has been resubmitted

Reports on this Submission

Anonymous Report 1 on 2023-3-30 (Invited Report)

  • Cite as: Anonymous, Report on arXiv:2209.03591v3, delivered 2023-03-30, doi: 10.21468/SciPost.Report.6972


The paper reports recent and interesting results on ultra-high energy cosmic rays (UHECRs) from the TALE and the TA observatories, which were recently presented at the ISVHECRI 2022. The contribution shows results on the energy spectrum, arrival directions and the composition of UHECRs. The TALE/TA observatory is the only UHECR detector on the northern hemisphere. Its data complements the measurements from the Pierre Auger observatory, which are done on the southern hemisphere.




The authors have addressed the major comments that were pointed out in the first review of the document. After reviewing the second version of the paper, I found some minor corrections and suggestions. Once such minor modifications are applied, I suggest to accept the paper for publication.

Requested changes

The list of changes and suggestions are listed in the attached PDF document .


  • validity: high
  • significance: high
  • originality: high
  • clarity: good
  • formatting: good
  • grammar: good

Author:  Hiroyuki Sagawa  on 2023-04-21  [id 3606]

(in reply to Report 1 on 2023-03-30)

Dear the reviewer,

Thank you very much for your detailed check. Basically I modified all as suggested as follows:

Best regards,
The author

Page 2
* (a) The sentence:” FD and SD are used to check SD energy by FD energy” seem to be incomplete. Could you please work out this line to clarify the point. For example: FD and SD are used to cross check the SD energy by using the FD energy measurements”
• Modified as suggested. Please see (b) below
* “profiles measured by FD including” —> “profiles measured with the FD by including”
• Modified as suggested
* (b) In “From SD near air shower cores on the ground” do you mean “from SD with air shower cores on the ground near the FD telescopes”
• For (a) and (b), the modification is made as follows:
• . Hybrid cosmic-ray events, which are detected simultaneously by FD and SD, are used to cross-check the SD energy by using the FD energy measurements and to improve mass composition identification from longitudinal shower profiles measured with the FD by the inclusion of SD information that better determines the directions of air-shower axes.
* views 31-59 —> views of 31-59
• Modified to “has a field of view of”
* array is totally 2.5 times —> array is 2.5 times
• Modified as suggested

Page 3
* Fig 2(left) —> Fig 2 (left) .
• Modified as suggested
* Fig 2(right) —> Fig 2 (right) .
• Modified as suggested
* In “(0.1-2.5)x10**19”, try to fit th length of the sentence to the that of the paragraph.
• Modified as suggested
* When we compare, after —> When we compare them, after
• According to the reviewer’s comment, I modified as follows:
• When we compare the energy spectra in the common declination band (−15◦ < δ < +24.8◦) after the ±4.5% rescalings,

Page 5
* Fig 4(left) —> Fig 4 (left) .
• Modified as suggested
* Fig 4(right) —> Fig 4 (right) .
• Modified as suggested

Page 6
* bias of about -10 g/cm2 is not corrected —> bias of about -10 g/cm2
• Modified as suggested
* With the observed break —> with the observed softening
• Modified as suggested
* with QGSJET-II-04 model —> with the QGSJET-II-04 model
• Modified as suggested

Page 7
* Fig 7. Increase the size of the figure.
• Modified as suggested
*respectively. A new excess —> respectively (see Fig. 9). A new excess
Modified as suggested

References 5 and 11: I suggest to use the same format for all titles of the references.
The same format is used for all titles of the references.



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