STAR Flow, Chirality and Vorticity PWG

["Liu, Xiaoyu" <liu.6566 AT buckeyemail.osu.edu>]

Hello Shinichi, 

Thanks for your suggestions. I updated my DNP slides with the new UrQMD plots (P9: 16 variable eta bins instead of 10 even eta bins) and the new version can be found at the same link: https://drupal.star.bnl.gov/STAR/presentations/dnp-2020/vn-measurement-auau-sqrtsnn-27-gev-event-plane-detector-star-1

For the v1 focus meeting, here is my slides: https://drupal.star.bnl.gov/STAR/system/files/v1_meeting_102020_0.pdf

If you are asking about the comparison between dN/deta of the simulated EPD hits (blue points on P5) and the dN/deta in the EPD acceptance extracted from the nMIP distribution with the real data, then I don't have it but I can make one later.

I didn't use any ADC cut and I am not sure if it is needed. Even the ADC is very small, the signal is still created by some particle hitting the EPD tile therefore it should be counted. The small value is just due to the Landau fluctuation. 

I am not sure if I understand your last suggestion. Do you mean for each EPD tile, I can measure the number of primary particles (generated particles) hitting the tile and the number of "simulated particles" (EPD hits after going through the STAR material simulation) hitting the tile? What do you want to learn from it?

Thanks,

Xiaoyu

---

From: Star-fcv-l <star-fcv-l-bounces AT lists.bnl.gov> on behalf of ShinIchi Esumi via Star-fcv-l <star-fcv-l AT lists.bnl.gov>
Sent: Wednesday, October 21, 2020 10:34 PM
To: STAR Flow, Chirality and Vorticity PWG <star-fcv-l AT lists.bnl.gov>
Subject: Re: [Star-fcv-l] STAR presentation by Xiaoyu Liu for DNP 2020 submitted for review

 

Dear Xiaoyu

Thank you, that makes sense. This would mean we should not plot the results 

with too small eta bins even for the input values to be compared with output values. 

On the other hand, in the real event we do have quite a large z-vertex variation, 

so eta average of each tile in each event are different, so one could still plot a little 

finer bins in eta, if we like to, so we need to think about the optimal size of the 

eta bin. I’m fine with your nice talk for DNP. 

Best regards, ShinIchi

PS : So the v1 vs eta in UrQMD and our data are quite different, which could be 

reasonable, because of the poor description of spectators. Do you also have a 

comparison of dN/deta between them? 

PPS : Sorry to ask you additional questions on your another presentation in v1 

focus meeting yesterday, where you were just binary counting hits in each tile of 

EPD to get measured v1 in MC, which is indeed reasonable, but did you exclude 

hits below the value of 0.5*ADC for one mip, that need to be applied after 

integrating all hits ADC values per tile in each HI event? 

Since you do have 2 ADC distributions for each tile and for both one mip (one 

particle event) and multi-mips (overlaid many single events) including landau 

and photon statistical fluctuation in addition to the real increase of the number 

of particles between the two, therefore you could also apply your nMip fitting 

method to see how well you can reconstruct the true “increase of” average 

number of particle per tile in the MC, which is a kind of good test ground of 

your approach and would also gives us the systematic error as well. You might 

need to have some constrained fitting of these two simultaneously, where they 

would have some common parameters in the function or do the fitting of the 

multi-mip data with a convoluted "data" function from the single-mip distribution. 

On Oct 22, 2020, at 1:44, Liu, Xiaoyu <liu.6566 AT buckeyemail.osu.edu> wrote:

Hello Shinichi, 

Attached are the UrQMD + EPD fast simulator study with 16 variable eta bins (corresponding to 16 EPD rings). The black points and red points are almost on top of each other. So the discrepancy at large |eta| on my slide 5 is indeed due to the fact that the innermost ring covers two eta bins. 

Please let me know if you have any other suggestions or comments.

Thanks,

Xiaoyu   

---

From: Liu, Xiaoyu <liu.6566 AT buckeyemail.osu.edu>
Sent: Sunday, October 18, 2020 8:07 PM
To: STAR Flow, Chirality and Vorticity PWG <star-fcv-l AT lists.bnl.gov>; ShinIchi Esumi <esumi.shinichi.gn AT u.tsukuba.ac.jp>
Subject: Re: [Star-fcv-l] STAR presentation by Xiaoyu Liu for DNP 2020 submitted for review

 

Hello Shinichi, 

Thank you for your comments and sorry I didn't show the results at recent BulkCorr meetings. As you mentioned, for this talk, I just want to focus on introducing the new method and the v1, v2 plots are indeed unnecessary for this purpose so I deleted them. 

About the UrQMD study, I used the full Au+Au UrQMD events, not the particle gun if it is what you are asking. And they are just UrQMD events w/o going through any simulation for the STAR materials. 

I believe the discrepancy in large |𝜂| is due to the fact that the inner-most ring covers two largest 𝜂 bins therefore EPD cannot tell exactly which 𝜂 bin the hit belongs to. So v1_EPDhit (4.8<|𝜂 |<5.1) = v1_EPDhit (4.5<|𝜂 |<4.8) and they are all between v1_track (4.8<|𝜂 |<5.1) and v1_track (4.5<|𝜂 |<4.8). As for the bin 4.2<|𝜂 |<4.5, part of it falls on ring 1 and part of it falls on ring 2 so the v1_EPDhit(4.2<|𝜂 |<4.5) will be pulled either towards the bin on the left or the bin on the right therefore v1_EPDhit(4.2<|𝜂 |<4.5) is smaller than v1_track (4.2<|𝜂 |<4.5) which is the peak of v1. In other words, if I plot the same plot with the x-axis bins being the 16 EPD rings instead of 10 even 𝜂 bins in [2.1,5.1], the red points and the black points are expected to be on top of each other. I can make the plot and show you later.

Sorry again for not discussing the results at BulkCorr earlier. Hope it will be okay if I only show the UrQMD results in this talk. I can present the UrQMD study in this week's FCV meeting if needed. 

I uploaded the second version under the same link: https://drupal.star.bnl.gov/STAR/presentations/dnp-2020/vn-measurement-auau-sqrtsnn-27-gev-event-plane-detector-star-1   

Please let me know if you have any other comments or suggestions.

Thanks,

Xiaoyu

---

From: Liu, Xiaoyu <liu.6566 AT buckeyemail.osu.edu>
Sent: Sunday, October 18, 2020 7:32 PM
To: STAR Flow, Chirality and Vorticity PWG <star-fcv-l AT lists.bnl.gov>; ShinIchi Esumi <esumi.shinichi.gn AT u.tsukuba.ac.jp>
Subject: Re: [Star-fcv-l] STAR presentation by Xiaoyu Liu for DNP 2020 submitted for review

 

Hello Jiangyong, 

Thank you for your comments, I implemented most of them except:

P3: I did use a random point on the tile to determine the \eta of a hit EPD tile.

P5: I changed the "the number of 1-, 2-, k-...MIP events per collision" to "the fraction....". The reason why I didn't use "probability" is that it is only the probability when we fit the dN/dnMIP of one tile, in which case the integral of the dN/dnMIP distribution over nMIP is 1. However, if we look at the dN/dnMIP of several tiles then the integral of the distribution will be larger than 1 and the sum of the 1, 2, 3, 4-MIP weights might be larger than 1 too and the word "probability" can be misleading. Then I realized the word "number" can be equally misleading since people would expect the number of events to be integers. Therefore, I chose "fraction" and hopefully it is less confusing. 

P9: The data points are not mirrored around y=0, they do look very similar though. 

Besides, I decided to delete the v1 before the resolution correction with the real data as Shinichi suggested since I want to focus on the new method and these plots are not essential for this purpose.

I uploaded the second version to the same link: https://drupal.star.bnl.gov/STAR/presentations/dnp-2020/vn-measurement-auau-sqrtsnn-27-gev-event-plane-detector-star-1   

Please let me know if you have any other comments or suggestions.

Thanks,

Xiaoyu 

---

From: Star-fcv-l <star-fcv-l-bounces AT lists.bnl.gov> on behalf of ShinIchi Esumi via Star-fcv-l <star-fcv-l AT lists.bnl.gov>
Sent: Saturday, October 17, 2020 11:54 PM
To: STAR Flow, Chirality and Vorticity PWG <star-fcv-l AT lists.bnl.gov>
Subject: Re: [Star-fcv-l] STAR presentation by Xiaoyu Liu for DNP 2020 submitted for review

 

Dear Xiaoyu

I could sign off your nice talk, but you have not discussed this in the 

PWG yet, so it would be nice that you could have shown us before. 

P7-8 : The statistical errors are invisible, but do you know why the difference 

between track(pure sim) and hit(including geant) is suddenly increasing at

|eta|>4. Are they a strong detector effect from a large dE/dx from spectator?

You use the true R.P. angle for both cases, is this geant simulation done 

taking a full AuAu event of UrQMD or taking a single track from the UrQMD 

event one by one? 

P9-10 : Do you like your data plots to be approved as preliminary even with 

the uncorrected data? (for E.P. resolution and BG and detector effects) 

If you insist to show these, I would at least label them more clearly that this 

is uncorrected for many possible other effects, not just for R.P. resolution) 

If you like to explain your analysis methods in detail, you would not need to 

use the experimental data, but can be done more with UrQMD data. It seems 

we do see a strong spectator contributions in both v1 and v2 (and most-likely 

in dN/deta distribution as well) in data, but you can not really defend what 

this is just with uncorrected data, so I wonder what we can say with these 

plots. 

Best regards, ShinIchi

On Oct 18, 2020, at 10:55, Jiangyong Jia via Star-fcv-l <star-fcv-l AT lists.bnl.gov> wrote:

Hi, xiaoyu,

Here is my comments for sign off

cheers,

Jiangyong

P1: please add "for the STAR Collaboration" and only keep your name

P2: For outline consider avoiding technical terms such as "nMIP" and StEpdFastSim in

P4: I would swap the order the two sub-bullet of the nMIP

P5: Fit to extract "the probability of 1-2..k-MIP events" in bin j

P6: please indicate the AuAu 27 GeV on this figure and also other figures where appropriate. 

resolution correction --> correct for the event plane resolution

P7: StEpdFastSim--> EPD fast simulation

same format as in the STAR offline data.

a random point on the tile--> do you mean the center of the tile?

P8: ring one--> the inner-most ring

 to correct for the measurement-->to account for residual detector effects

The plots have been symmetrized around y=0, if so please indicate that

P10: please add some statement on this slide

Plots on P8-P10 should have proper x- and y-axis labels

P11: we developed a new method

On 10/15/20 11:53 AM, webmaster--- via Star-fcv-l wrote:

Dear star-fcv-l AT lists.bnl.gov members,

Xiaoyu Liu (liu.6566 AT osu.edu) has submitted a material for a review, please  
have a look:
https://drupal.star.bnl.gov/STAR/node/52381

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