Eco-gas meeting RPC ATLAS+CMS+EPDT+LCHb/Ship


Let's try to use zoom



    • 3:00 PM 3:20 PM
      status of the system 20m
      Speaker: Luca Quaglia (Istituto Nazionale di Fisica Nucleare)
      • Preliminary schedule of the 2024 TB -> only the first period (in April) is almost 100% sure, the other two can still vary. This is not yet super official but April should stay like this
      • During the GIF++ consolidation program (YETS 2024/25) they are planning to install a dedicated HFO line!
    • 3:20 PM 3:40 PM
      discussion on EcoGas paper TB2022 20m
      Speakers: Dayron Ramos Lopez (Istituto Nazionale di Fisica Nucleare), Luca Quaglia (Istituto Nazionale di Fisica Nucleare)

      Here are the comments we received by the journal, we have time until March 18th to submit the updated version:

      Ms. No. EPJP-D-23-04181
      Preliminary results on the long term operation of RPCs with eco-friendly gas mixtures under irradiation at the CERN Gamma Irradiation Facility
      The European Physical Journal Plus

      Dear Mr. Quaglia,

      Reviewers have now commented on your paper and are advising that you revise your manuscript (major revisions).  If you are prepared to undertake the work required, I would be pleased to reconsider my decision.

      The reviewers' comments can be found at the end of this email or can be accessed by following the provided link.

      When revising your work, please submit a list of changes or a rebuttal against each point which is being raised when you submit the revised manuscript.

      Your revision is due by 18-03-2024.

      To submit a revision, go to and log in as an Author. You will see a menu item called 'Submissions Needing Revision'. You will find your submission record there.

      If you are decided not to resubmit the paper to The European Physical Journal Plus please do let us know without delay so that we can withdraw your paper. This is in particular mandatory if you wish, e.g., to submit your paper to another journal instead.

      Yours sincerely

      Archana Sharma
      Guest Editor
      The European Physical Journal Plus

      Reviewers' comments:

      Reviewer #1: The submitted manuscript is about a joint effort by various groups to find the eco-friendly gas mixtures solution to operate RPC detectors without compromising the performance. The currently used gas mixtures for the RPC detectors have high GWP so in order to reduce the harm to the environment as well as to follow the various national and lab wide policies about reducing or completely eradicating the use of high GWP gases in the scientific research, it is imperative to find solutions for gas mixtures which allows for continuous operation of gas based detectors. The studies presented in the current manuscript is a step towards achieving this goal. 
      The authors have constructed a set of RPC detectors with different gaps, area and electrode thickness with varying strips and readout. These detector have been operated with various gas mixtures under different operating conditions and the performance in terms of efficiencies, charge distribution, signal strength and cluster size have been evaluated. A very preliminary effort to evaluate the ageing effect of RPC detectors under new eco-friendly gases has also been undertaken. The manuscript in general contains a set of measurements for various RPCs with the new mixtures and comparison have been performed with the standard gas mixtures. However, the manuscript seriously lacks in performing an analysis to compare the performance of various RPCs operated under similar or different working conditions. It appears that authors have simply presented their measurements as it is and they left it for the readers to draw conclusions for themselves. Also, the paper lacks clarity when it
      comes to communicating the message to the readers and the community. It appears to me that the different sections of the manuscript has been written by different people and a cohesive effort is lacking in joining the dots. Even the numbers/figures/plots are not consistent throughout the manuscript. The manuscript contains a set of important studies which could be very useful in finding the solution towards eco-friendly gas mixtures to operate RPC detectors but its important for the authors to present these results to the community in a much more lucid and clear way with firm conclusions from their study. As such I recommend a thorough revision of the manuscript before it can be considered for publication.
      Below I provide my detailed comments/questions on the manuscript.
      General comment: The language of the manuscript needs to be improved significantly. There are several grammatical mistakes that can simply be corrected using any modern day English language software or by a native speaker. Acronyms have been used throughout the manuscript without explaining them at least for the first time when they appear. 

      Detailed comments:
      - L79: Please mention the GWP of the third gas used to operate the RPCs at CERN as well.
      - L82: Experts -> users or physicists (its unbecoming to call oneself as experts if though they are)
      - L85: Its understood that an eco-friendly replacement is required for all the GHGs so why the paper is focussed only on finding the replacement for C2H2F4 only? Even though the percentage wise the SF6 contribution is only 1% but looking at the total volume of gases used to operate RPCs at CERN experiments this would still be significant.
      - L91- Moderate flammability -> Please quantify or elaborate because even a moderate flammability is still not good.
      - L95: Please provide a reference in support of this statement or quantify the increase in working voltage
      - L101: two sided -> two pronged or bi-directional
      - L104-105: Not a clear statement. What do you mean by simulated by performing aging test? It's a simply prolong operation of RPC with eco-friendly gas mixture or something more is being communicated here?
      - L106: simulating -> Mimicking
      - L140: sends -> sending it to detectors. Gas flow, ….
      - L151-152: Provide a reference in support of this statement. 
      - L155: few ten of V -> a few tens of volt
      - L166: highlighted -> highlighting
      - L167: 3 and 6 m -> 3 m and 6 m or 3 and 6 meters
      -L 168: (blue rectangles, the internal ones and red rectangle, the external ones)
      - L180: specific front end electrons -> Please provide a bit more detail on these front end boards or provide a reference for the sake of clarity
      Table 2: In the eco-friendly gas mixture, which gas is acting as a primary ionising gas under different compositions? Why SF6 concentration increased from 0.3% in STD to 1% in all other gas mixtures? Shouldn't this increased concentration should also be taken into account while comparing the performances with the STD mixture?
      - L213-215: The different digitizer time window for different RPCs would make the comparison of their performances difficult unless it has been accounted in while carrying out the analysis, for eg. While looking at the charge distribution or signal strength? I suggest re-writing this paragraph by adding more information and explanation.
      - Fig. 3: Follow consistent labelling and legends.
      - Fig. 3: The fit of STD plateau in right panel seems to be quite bad. The efficiency seems continue to rise while fit becomes flat. Since the error bars on these numbers are not visible so I assume that they are quite small. 
      - Fig. 3, left panel: The current density plot seems to be problematic. It has non-zero value before 9000 V and then goes to zero and then suddenly rises to more than 1 nA/cm^2 around 9700 V. What is the cause of such behaviour? Doesn't seem like a random fluctuations. The right panel current density seems stable.
      - L228: Is it 30/65 or 35/60 as mentioned in the Table 2?
      - L233-234: How is asymptotic efficiency extracted, for eg. In Fig. 3 (right panel) for STD gas mixture?
      - L242: Is CO2 acting as primary ionising gas here? 
      -L246: Is CO2 decreasing from 69% to 65 or 60%?
      -L246: plateau efficiency increases from ECO3 to ECO2. How? Which figure? This is clearly not the case in Fig. 3. The efficiencies seems pretty much the same for the 2 mixtures. L
      - L285-286: Shouldn't the charge collected be more with the lower threshold value? 
      -L300: Of course -> But, 
      -L301: Is HFO acting as a quenching gas or an ionising gas? If this is a quenching then CO2 is ionising? This seems confusing because in L245-246 an opposite effect is observed where by decreasing the ionising gas (presumably CO2) the efficiency is claimed to increase though its not seen in Fig. 3. Please see above comments.
      - Again in L320-321, it is being claimed that by increasing the HFO fraction above 50% is advisable in order to reach high efficiency plateau. This claim is opposite to the effect described in L301. So basically section 3.1.3 is not consistent with the earlier paras. 
      L324-325: The statement about increase of working point also increases with the HFO concentration increase is true if HFO is acting as quenching gas.
      Fig. 6: Please use label large signal probability or Streamer probability in both the panel to be consistent. Since in the text you clarified that its large signal probability so use that instead.
      - Fig. 6, left panel: The probability for ECO3 and MIX4 seems to be same but then there is a drop for ECO2. What is the explanation for this? MIX4 is in between ECO3 and ECO2 so this is so clear. Please explain. Also, what is the order of errors on these numbers? In the right panel, why is there a few percent probability for ECO3 below threshold voltage around -11k? Also, the STD and ECO3 data is not plotted beyond 500V? 
      -L337-339: Again, if CO2 is primary ionising gas then shouldn't efficiency increase with increase in its concentration? 
      -L347: ad -> as
      -Fig. 7: Adding HFO decreases the efficiency in higher background but adding further more HFO increases the efficiency (middle panel). This is surprising. What could be the reason behind it. No explanation is provided.
      L359-360: The statement is not true according to data in Fig. 8. In fact, ALICE and EP-DT detectors shows very different rates, almost a factor of 2 different. Am I missing something here? 
      L360-362: How is the variation with the distance? 1/r^2 or 1/r? Please clarify.
      L364-365: Again, the results are not comparable. The right panel of Fig. 8 shows a large variation in rates for different gas mixtures. The rates vary by more than a factor of 2. Since these two detectors are at the same distance so dependence on distance is not a factor here but still they are very different. 
      Fig. 8, right panel: There is also a big variation in the rates for various gas mixtures which doesn't show any particular pattern. For eg. ECO2 rates at around 20 ABS is about 100 whereas ECO3 is almost around 180 with STD in between. This is again very surprising. The similar variation is not present in the Fig. 8 left panel. In Fig. 9, the ECO3 and ECO2 rates are very similar for the ABS of 20 but again different for ABS of 10. So all these three figures doesn't seem to be in agreement with each other and appears to convey different messages.
      While the gaps for BARI and EP-DT are different but its same for ALICE and EP-DT so again this doesn't explain the variations amongst different detectors and different mixtures.
      - L381: Only the last data point for ECO3 drops significantly otherwise the variation is efficiencies seems consistent. What could be the cause for this?
      -Fig. 10: Why the efficiencies are different for the same gamma cluster size between ALICE and EP-DT even though they are having similar detector parameters? 
      -L391-393: So what is the conclusion? Is 1mm gap better for the RPC performance? 
      -L396: is a significance feature -> is of significance 
      - Fig. 14: The data right panel is having large error bars for ECO2 and ECO3 but more data should have been collected with these mixtures instead. Also, since the ALICE and BARI detectors are different so what is being compared here? 
      - What is the cause for the large current in the BARI detector? Was it investigated?
      - L446: Indeed->Moreover, 
      - Fig. 16: Please explain this figure in more detail as it contains too much information which has not been explained in the text. For eg. What are dotted lines?
      - L477-481: There are just too many free parameters and variations allowed in the study so it would be difficult to conclude things succinctly from this. 
      - L506-508: While Fig. 17 shows an increasing trend of Ohmic dark current in the beginning but it doesn't shows a stable behaviour for higher values. A distribution of the order of 30-40% can be seen all over at higher values for the left panel of the Fig. so I really do not see a stable behaviour. The right panel figure does shows a more stable behaviour for the 9.8kV range. An explanation for this randomness would be needed or else the authors need to quantify what they mean by stable behaviour.
      - What is the reason for a factor of 2 difference in the integrated charge density between SHiP and EPDT even though their efficiencies do not differ by a factor of 2?
      - Section 4.2 ends without any analysis and conclusion so what the readers are supposed to learn from it? Its understood that these are very preliminary results for aging studies and hence authors may not be willing to draw any conclusion but the authors at least must explain what they learned from their observations and what other studies are needed in order to draw some concrete conclusions.
      -L532-535: It seems that the efficiency is always a bit lower with irradiation while it is claimed otherwise in these lines.
      -L540-542: Again what is claimed here is not supported by Figs. 3 and 6. These figures clearly shows that the operating region increased for eco-friendly alternatives. Or are these conclusions based on some other figures? If so then please state?
      -L553 & 554: Dangling division sign?
      -L555: visible -> pronounced
      -L558: ECO->ECO2 (35/50 or 35/60)?
      -L561-562: Again Figs. 16 & 17 does not show stable current under irradiation over time? Should we be looking at some other figure to draw this conclusion?
      -L563: will -> would be 
      -L568: lead ->led
      -L571: eco-friendly alternatives -> eco-friendly alternatives studies in this manuscript.

    • 3:40 PM 4:00 PM
      Report on dark rate studies on the EPDT RPC6 detector 20m
      Speakers: Luca Quaglia (Istituto Nazionale di Fisica Nucleare), Mattia Verzeroli
    • 4:00 PM 4:20 PM
      details of proposal of a Test from Munich group 20m
      Speaker: giorgia proto (Max-Planck-Institut f\"ur Physik)
    • 4:20 PM 4:40 PM
      a.o.b. 20m