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Subject: sPHENIX is a new detector at RHIC.
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Re: [Sphenix-l] sPHENIX Beam Use Proposal 2023 v1 - comments due 23 August
- From: Jamie Nagle <jamie.nagle AT colorado.edu>
- To: sPHENIX-l Digest <sphenix-l AT lists.bnl.gov>
- Subject: Re: [Sphenix-l] sPHENIX Beam Use Proposal 2023 v1 - comments due 23 August
- Date: Wed, 23 Aug 2023 14:49:16 -0600
Hello Dennis and sPHENIX,
Thank you for the hard work in producing this draft Beam Use Proposal on a short time scale and with changing boundary conditions. I realize that it is a challenging task. I should also note I am very impressed with the companion Commissioning Document and the huge amount of work that has been accomplished out in 1008.
Below I include some easy fixes, as well as some more important comments and future "todo" items.
Sincerely,
Jamie
----
Executive Summary
line 20 - what about the TPOT?
line 22 - when you have e.g., there are some instances without the comma
line 24 - I would include the exact dates as May 18, 2023 and August 1, 2023 and note explicitly this is approximately 11 weeks total. The start date corresponds to BHSO approval - use the exact text from the Commissioning Document. It really points out the amazing achievements that were accomplished on commissioning in basically just 11 weeks!
line 25 - seems rather overstated. Even detectors that were running like EMCal and MBD for example have not verified performance specifications almost at all (e.g., energy resolution, time or z-vertex resolution). This also needs to be smoothed with the Commissioning Document where possible.
line 27 - "multiple weeks" is vague and actually not so clear in the document. Even if in reality we do not know exactly how much commissioning is needed and for what systems, it should be spelled out what is used to calculate integrated luminosities that appear later.
line 34 - it should really be clarified with the ALD if they are requiring the 6 cryo weeks carried over be for AuAu - just so we know whether that was part of some official carry over agreement.
*** I am really unclear why this has not been clarified officially as it has important implications beyond the PAC and in terms of flexibility. Is there some chance the agreement between DOE and BNL to carry the funds had this written down as a requirement... In Table I in the Executive Summary we repeat that it is + 6 weeks AuAu, and we want to not communicate that constraint if it is not a hard constraint.
line 34 - it could be in the middle - which you added later, but not here...
*** In an informal lunchtime chat with Wolfram on Monday, he specifically brought up that the AuAu could be in the middle. He noted that the heat dumped into the various RHIC buildings, including 1004B, is 500% higher with AuAu @ 200 GeV compared with pp @ 200 GeV, and thus even having AuAu in April and then switching back to pp was highly preferable. He also said that switching back might just incur a 2-3 day turnaround time. Yes, we have to switch some timing oscillators on some 20ish boards, but that is in the noise.
*** My preference in the BUP is to have this as the default scenario, and then say that in the coming months we should work with C-AD and the new information on sPHENIX readiness to optimize that timing. No reason for the PAC to recommend or the ALD to decide in early September.
line 37 - I would state right up in the Executive Summary that C-AD with new experience has changed from the minimum being past experience to the maximum being past experience because of the long time since last running pp and AuAu 200 GeV -- the PAC needs to read this up front.
*** We want to be careful not to be criticizing C-AD, but the ALD and PAC should easily understand the change. Also, in the language in later Chapters, I would change the tone slightly to not imply that C-AD did not give us enough time -- they were also experiencing major boundary conditions and new running changes.
line 41 - you are missing 4-5 (but why is it a range - quote exact value)
line 74 - you should add "in future years" to make it explicit that there is no scenario for this year
Appendix C - this is outdated -
*** There may be some confusion regarding AuAu sampled versus recorded, and this should be clarified (at least within sPHENIX). In the BUP2020 with those projections, there was something like a factor of 2 - 2.5 larger than 15 kHz of AuAu collision rate within |z|<10 cm. Thus, in principle we could sample this extra factor of 2 with selective Level-1 triggering over the recorded minimum bias data (which is limited by the 15 kHz). The only such trigger that was simulated and checked and definitely works in the high pT photon trigger. It is possible that a high pT > 50 GeV jet trigger would work, but no real scheme for underlying event subtraction was worked out nor an FPGA algorithm developed.
Thus, even though the C-AD projections since BUP2020 have dropped by a factor of ~ 4 (a factor of x2 in beam intensity and another factor of x2 for the surprisingly larger loss in collision rate with the 2 mrad crossing angle), we only lose that factor of x4 for direct photons and only about a factor of x2 for everything else.
The drop in AuAu from the BUP2020 by x2.4 as used in the document (which is close to the x2 above) is far from optimized. I am working on calculations that can be optimized that show that with more like a 5 hour store, and with changing the crossing angle from either 2 or 1 mrad to zero about 2.5 hours into the store (which Wolfram said was quite doable) that we might only be losing 20% or so. That probably is not so important for this BUP other than saying in addition to pushing C-AD, getting more cryo-weeks where possible, we also have some positive options. I worry that the large drop sends too negative a message and that we have not optimized at all and just taken it as given.
* I find the formatting of Table I a bit awkward and would prefer to have the header with column labels connected to the values, even if that means repeating it for Run 2024 and then for Run 2025.
----
Chapter 1
Figure 1 caption has not been updated for the additional subsystems now included :)
----
Chapter 2
line 180 - why is "THIS" in all capitals?
line 181 - now the phrase "with an additional six weeks earmarked for Au+Au running" is used. "earmarked" has a very specific meaning in budgets -- again what has been confirmed about this condition?
line 190 - I would suggest removing the "shortly before" and just say when it was updated.
line 193 - again, I would remove "shortly before" and just have the date. Grousing will get us nothing, even if it is true :)
line 195 - I prefer not to have percentages and factors mixed together. I would pick one and stick with it. Factors are best in my view, but either one works.
line 197 - what does "4-5" mean? Isn't it an exact value that we can quote -- good to be precise and be able to show the PAC exactly how this was calculated when asked.
line 213 - I would quote the exact values that are being used in a Table. One could also include the MBD z-vertex figure with 0, 1, 2 mrad crossings from the Commissioning Document.
line 220 - needs space between the number and "mrad" in both cases.
line 224 - "to determine" -> "to be determined"
*** What is your assumption on the maximum total number of tracks the TPC can handle? That then translated into how many AuAu or pp collisions at any z-vertex that we can nominally run at. This switch to 1 mrad would change the fraction inside |z| < 10 and outside. Can you detail at least for sPHENIX the numbers here, and maybe in the BUP? It may not be in time for the BUP, but I now have numbers for the luminosity as a function of time in store with the three crossing angles and we should check on these "leveling" options.
line 238 - "with the possible exception of the six weeks allotted to Au+Au running" -- this is the first real mention that the proposal sounds like all pp, and only considering AuAu as a "possible exception". This seems inconsistent in message and language.
line 239 - "We strongly stress the critical" Maybe just say "stress" or have this in the Executive Summary - if this is the most important item (in bold even).
line 242 - "or" -> "and"
line 247 - "it is now only possible to collect a similar dataset through exclusive p+p running in 2024 for as many cryoweeks as possible." -- this does not make sense as a sentence. Are we falling short in any scenario or be more specific.. Is the dominant / co-dominant also incorporating the reduced AuAu?
line 254 - "Regarding the six weeks of Au+Au running, sPHENIX has prepared two example scenarios depending on whether that running is at the beginning or end of run 2024. There are benefits to either scenario"
*** Now we are again conceding that it must be 6 weeks. This makes it sound like we have no idea and STAR could just decide. Again, my preference is to switch this to April 2024 and then adjust from there. I believe it is very important to not just concede this schedule point away.
*** Also, the statement that this can be decided in the "coming months" --> "months" is a bit vague given that the run may start January 8, 2024 (that is 20 weeks that C-AD needs, so the earliest start date). See my point above.
line 262 - now you refer to 4 weeks (? confusing to the reader). You have not yet shown the cryo-week tables and in those it has 3 weeks of regular AuAu beam operations. Very important to have all numbers consistent and with language consistent between tables and sections.
line 283 - just double checking on the following line: "In addition, the p+Au luminosity projections are strongly decreased in the recent guidance update, with overall luminosity production per week down by a factor of two, with another approximate factor of two decrease when one considers a non-zero crossing angle and narrow-vertex collisions."
I know the AuAu has the effect of an extra decrease with non-zero crossing angle, however, if C-ADs hypothesis is right about this being an interaction with stochastic cooling, I thought they said this would not apply to pp. What did they actually say regarding pAu?
line 296 - space between number and mrad
line 305 - "15kHz" -> "15 kHz"
line 322 - "Chapter D" -> "Appendix D?"
Table 2.5 - caption says "pAu" but that has been removed
Table 2.5 - is this just minimum bias AuAu (which I think it implies but is not in the caption)? Is that the right comparison and matching the earlier language about dominant / subdominant statistical uncertainties between pp and Auau? Should it be for a given centrality like 0-10%?
---
Future Chapters
"Due to the circumstances of the late-arriving luminosity projections from C-AD, the physics projection plots presented in Chapters 3.1– 3.4 are identical to those from the previous year’s Beam Use Proposal, and are labelled “BUP 2022”."
I would try to find a more conciliatory language rather than "late-arriving". C-AD is our friend.
Sincerely,
Jamie
----
Executive Summary
line 20 - what about the TPOT?
line 22 - when you have e.g., there are some instances without the comma
line 24 - I would include the exact dates as May 18, 2023 and August 1, 2023 and note explicitly this is approximately 11 weeks total. The start date corresponds to BHSO approval - use the exact text from the Commissioning Document. It really points out the amazing achievements that were accomplished on commissioning in basically just 11 weeks!
line 25 - seems rather overstated. Even detectors that were running like EMCal and MBD for example have not verified performance specifications almost at all (e.g., energy resolution, time or z-vertex resolution). This also needs to be smoothed with the Commissioning Document where possible.
line 27 - "multiple weeks" is vague and actually not so clear in the document. Even if in reality we do not know exactly how much commissioning is needed and for what systems, it should be spelled out what is used to calculate integrated luminosities that appear later.
line 34 - it should really be clarified with the ALD if they are requiring the 6 cryo weeks carried over be for AuAu - just so we know whether that was part of some official carry over agreement.
*** I am really unclear why this has not been clarified officially as it has important implications beyond the PAC and in terms of flexibility. Is there some chance the agreement between DOE and BNL to carry the funds had this written down as a requirement... In Table I in the Executive Summary we repeat that it is + 6 weeks AuAu, and we want to not communicate that constraint if it is not a hard constraint.
line 34 - it could be in the middle - which you added later, but not here...
*** In an informal lunchtime chat with Wolfram on Monday, he specifically brought up that the AuAu could be in the middle. He noted that the heat dumped into the various RHIC buildings, including 1004B, is 500% higher with AuAu @ 200 GeV compared with pp @ 200 GeV, and thus even having AuAu in April and then switching back to pp was highly preferable. He also said that switching back might just incur a 2-3 day turnaround time. Yes, we have to switch some timing oscillators on some 20ish boards, but that is in the noise.
*** My preference in the BUP is to have this as the default scenario, and then say that in the coming months we should work with C-AD and the new information on sPHENIX readiness to optimize that timing. No reason for the PAC to recommend or the ALD to decide in early September.
line 37 - I would state right up in the Executive Summary that C-AD with new experience has changed from the minimum being past experience to the maximum being past experience because of the long time since last running pp and AuAu 200 GeV -- the PAC needs to read this up front.
*** We want to be careful not to be criticizing C-AD, but the ALD and PAC should easily understand the change. Also, in the language in later Chapters, I would change the tone slightly to not imply that C-AD did not give us enough time -- they were also experiencing major boundary conditions and new running changes.
line 41 - you are missing 4-5 (but why is it a range - quote exact value)
line 74 - you should add "in future years" to make it explicit that there is no scenario for this year
Appendix C - this is outdated -
*** There may be some confusion regarding AuAu sampled versus recorded, and this should be clarified (at least within sPHENIX). In the BUP2020 with those projections, there was something like a factor of 2 - 2.5 larger than 15 kHz of AuAu collision rate within |z|<10 cm. Thus, in principle we could sample this extra factor of 2 with selective Level-1 triggering over the recorded minimum bias data (which is limited by the 15 kHz). The only such trigger that was simulated and checked and definitely works in the high pT photon trigger. It is possible that a high pT > 50 GeV jet trigger would work, but no real scheme for underlying event subtraction was worked out nor an FPGA algorithm developed.
Thus, even though the C-AD projections since BUP2020 have dropped by a factor of ~ 4 (a factor of x2 in beam intensity and another factor of x2 for the surprisingly larger loss in collision rate with the 2 mrad crossing angle), we only lose that factor of x4 for direct photons and only about a factor of x2 for everything else.
The drop in AuAu from the BUP2020 by x2.4 as used in the document (which is close to the x2 above) is far from optimized. I am working on calculations that can be optimized that show that with more like a 5 hour store, and with changing the crossing angle from either 2 or 1 mrad to zero about 2.5 hours into the store (which Wolfram said was quite doable) that we might only be losing 20% or so. That probably is not so important for this BUP other than saying in addition to pushing C-AD, getting more cryo-weeks where possible, we also have some positive options. I worry that the large drop sends too negative a message and that we have not optimized at all and just taken it as given.
* I find the formatting of Table I a bit awkward and would prefer to have the header with column labels connected to the values, even if that means repeating it for Run 2024 and then for Run 2025.
----
Chapter 1
Figure 1 caption has not been updated for the additional subsystems now included :)
----
Chapter 2
line 180 - why is "THIS" in all capitals?
line 181 - now the phrase "with an additional six weeks earmarked for Au+Au running" is used. "earmarked" has a very specific meaning in budgets -- again what has been confirmed about this condition?
line 190 - I would suggest removing the "shortly before" and just say when it was updated.
line 193 - again, I would remove "shortly before" and just have the date. Grousing will get us nothing, even if it is true :)
line 195 - I prefer not to have percentages and factors mixed together. I would pick one and stick with it. Factors are best in my view, but either one works.
line 197 - what does "4-5" mean? Isn't it an exact value that we can quote -- good to be precise and be able to show the PAC exactly how this was calculated when asked.
line 213 - I would quote the exact values that are being used in a Table. One could also include the MBD z-vertex figure with 0, 1, 2 mrad crossings from the Commissioning Document.
line 220 - needs space between the number and "mrad" in both cases.
line 224 - "to determine" -> "to be determined"
*** What is your assumption on the maximum total number of tracks the TPC can handle? That then translated into how many AuAu or pp collisions at any z-vertex that we can nominally run at. This switch to 1 mrad would change the fraction inside |z| < 10 and outside. Can you detail at least for sPHENIX the numbers here, and maybe in the BUP? It may not be in time for the BUP, but I now have numbers for the luminosity as a function of time in store with the three crossing angles and we should check on these "leveling" options.
line 238 - "with the possible exception of the six weeks allotted to Au+Au running" -- this is the first real mention that the proposal sounds like all pp, and only considering AuAu as a "possible exception". This seems inconsistent in message and language.
line 239 - "We strongly stress the critical" Maybe just say "stress" or have this in the Executive Summary - if this is the most important item (in bold even).
line 242 - "or" -> "and"
line 247 - "it is now only possible to collect a similar dataset through exclusive p+p running in 2024 for as many cryoweeks as possible." -- this does not make sense as a sentence. Are we falling short in any scenario or be more specific.. Is the dominant / co-dominant also incorporating the reduced AuAu?
line 254 - "Regarding the six weeks of Au+Au running, sPHENIX has prepared two example scenarios depending on whether that running is at the beginning or end of run 2024. There are benefits to either scenario"
*** Now we are again conceding that it must be 6 weeks. This makes it sound like we have no idea and STAR could just decide. Again, my preference is to switch this to April 2024 and then adjust from there. I believe it is very important to not just concede this schedule point away.
*** Also, the statement that this can be decided in the "coming months" --> "months" is a bit vague given that the run may start January 8, 2024 (that is 20 weeks that C-AD needs, so the earliest start date). See my point above.
line 262 - now you refer to 4 weeks (? confusing to the reader). You have not yet shown the cryo-week tables and in those it has 3 weeks of regular AuAu beam operations. Very important to have all numbers consistent and with language consistent between tables and sections.
line 283 - just double checking on the following line: "In addition, the p+Au luminosity projections are strongly decreased in the recent guidance update, with overall luminosity production per week down by a factor of two, with another approximate factor of two decrease when one considers a non-zero crossing angle and narrow-vertex collisions."
I know the AuAu has the effect of an extra decrease with non-zero crossing angle, however, if C-ADs hypothesis is right about this being an interaction with stochastic cooling, I thought they said this would not apply to pp. What did they actually say regarding pAu?
line 296 - space between number and mrad
line 305 - "15kHz" -> "15 kHz"
line 322 - "Chapter D" -> "Appendix D?"
Table 2.5 - caption says "pAu" but that has been removed
Table 2.5 - is this just minimum bias AuAu (which I think it implies but is not in the caption)? Is that the right comparison and matching the earlier language about dominant / subdominant statistical uncertainties between pp and Auau? Should it be for a given centrality like 0-10%?
---
Future Chapters
"Due to the circumstances of the late-arriving luminosity projections from C-AD, the physics projection plots presented in Chapters 3.1– 3.4 are identical to those from the previous year’s Beam Use Proposal, and are labelled “BUP 2022”."
I would try to find a more conciliatory language rather than "late-arriving". C-AD is our friend.
||------------------------------------------------------------------------------------------
|| James L. Nagle
|| Professor of Physics, University of Colorado Boulder
|| James L. Nagle
|| Professor of Physics, University of Colorado Boulder
|| EMAIL: jamie.nagle AT colorado.edu
|| SKYPE: jamie-nagle
|| WEB: http://spot.colorado.edu/~naglej
||------------------------------------------------------------------------------------------
|| SKYPE: jamie-nagle
|| WEB: http://spot.colorado.edu/~naglej
||------------------------------------------------------------------------------------------
On Mon, Aug 21, 2023 at 4:26 PM Perepelitsa, Dennis via sPHENIX-l <sphenix-l AT lists.bnl.gov> wrote:
Dear sPHENIX colleagues,
I invite your comments on draft v1 of the 2023 Beam Use Proposal.
You may find the document in Invenio here:
and conveniently as a attachment under the BUP Indico contribution in last week’s GM:
Any comments received by the end of Wednesday, 23 August would be very useful. Again, I realize the timing is very tight - this is largely a consequence of us processing the late-arriving projections from C-AD and discussing the strategy around them. I would appreciate comments on the specific proposals and the overall framing and arguments, as well as more minor editorial/mechanical comments on the text.
The sections with the most substantially new material are the Executive Summary, Chapter 2 introduction through 2.2, and the introduction to Chapter 3.
As a reminder, detailed discussion of the commissioning status and plans have been moved to the separate commissioning document circulated by John Haggerty, and are only briefly alluded to in the BUP document.
Dennis
Dennis V. Perepelitsa
Associate Professor, Physics Department
University of Colorado Boulder
-
[Sphenix-l] sPHENIX Beam Use Proposal 2023 v1 - comments due 23 August,
Perepelitsa, Dennis, 08/21/2023
- <Possible follow-up(s)>
- Re: [Sphenix-l] sPHENIX Beam Use Proposal 2023 v1 - comments due 23 August, Jamie Nagle, 08/23/2023
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