Electrostatic Simulations for the DUNE ND-GAr Field Cage

Round 1

Reviewer 1 Report

This article uses Elmer finite-element software to simulate the electrostatics of the proposed DUNE ND-GAr. Aspects as field uniformity, field distortion due to stripe spacing, and residual field are simulated and analyzed in this paper. 

General Comment:

The authors did a very thorough study of the electric fields in the ND-GAr detector. It is not trivial to carry out a careful analysis of the electric field properties, which impact greatly the precision of the positional information of the detector.  That said, there are a few aspects of this paper that can use some improvement. 

One major confusion I have is the purpose of this research. The simulation focused on the dual anode design, where a single anode is more likely to be used.  Moreover, there is a Ph.D. thesis on the E-field simulation ALICE detector by Stefan Rossegger [CERN-THESIS-2009-124], which covers many of the aspects discussed in this article. The comparison of the results is lacking, given the designs are essentially the same, or similar. I feel like there is some tension with the ALICE result, but discussions and references on this are lacking. 

Second, the scope of the simulation is unclear. I am worried the simulation at this stage is too ideal: it does not take into account the charge-up at TPC walls, and some basic structures that need modeling(IROC, OROC). With that, the result is rather inconclusive to be a full simulation.  So I would suggest to focus on simpler issues such as the optimal strip spacing. 

Third, there is no definition of the coordinate system. This makes half of the results unclear to readers. 

Last, a very personal opinion, I think the discussion on particle physics is not the focus of this paper. IMHO this will be better suited to be published in Instruments (https://www.mdpi.com/journal/instruments). 

Minor Issues:

Better to have E-field lines. 

No conclusion. 

Specific comments: 

L85: designs->design

L116: shouldn't smaller ESF = better? why is it unuseful to have a smaller grid? 

L119: need reference for 400V/cm

Figure 6,7: what are each boundary? 

Author Response

Thank you for comments on article 1618295.  See responses in blue in the attached word document.

Author Response File: Author Response.pdf

Reviewer 2 Report

This paper is nicely written and shows goof technical work. The understandability would be improved by including the coordinate system definition in Figures 1, 2, 3 and 4.

Author Response

Thank you for comments on article 1618295.  Responses are in blue in the attached word document.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Thank the authors for the reply. Nice technical report, fits the special edition topic well. Looking forward to seeing the continuing study on this. 

PS. I can't find where ref 15 is in the text.