Commissioning and running of sPHENIX

["Yip, Kin" <kinyip AT bnl.gov>]

Hi Rosi,

I agree with your arithmetics except probably "0.08 L is in |z|>10 cm" should be "0.09 L is in |z|>10 cm" (because 0.25 - 0.16  = 0.09).

That's how I understand it also.

Kin

On 9/21/23 13:25, Rosi Reed wrote:

Hi Kin,

Let me make sure I understand the math correctly.  If L is the full luminosity without a crossing angle, then in that case we have 0.2L in +/- 10 cm and 0.8L |z| > 10 cm.

With a 1 mrem crossing angle, looking at the plot, the total luminosity for pp is reduced to 0.4 L.  But, the luminosity in +/- 10 cm is 94% of the no-crossing angle case, or 0.94 x 0.2 = 0.19 L.  This means 0.21L is in |z| > 10 cm.

With 1 2 mrem crossing angle, the total luminosity is reduced to 0.25 L.  The luminosity in +/-10 cm is 79% of the no crossing case, so 0.79 x 0.2 = 0.16L.  This means that 0.08 L is in |z|>10 cm.

So naively, assuming I understood the math, we would want to figure out how much luminosity delivered in |z| > 10 cm is problematic for the tpc and set the angle accordingly?  It seems that no matter what, we lose out on luminosity in the sweet spot, so the future decision really will be in understanding what level of background we tolerate?

Sorry for repeating the mail - I wanted to make sure I understood it.

Cheers,

Rosi

On Thu, Sep 21, 2023 at 12:26 PM Yip, Kin <kinyip AT bnl.gov> wrote:

Please see the plot and the message/explanation below from Chuyu Liu for his calculation about luminosity reductions (within z= +/- 10 cm  or outside)  for pp.

 

Kin

 

From: Liu, Chuyu <cliu1 AT bnl.gov>
Sent: Thursday, September 21, 2023 12:19 PM
To: Yip, Kin <kinyip AT bnl.gov>; Hock, Kiel <khock AT bnl.gov>
Cc: Fischer, Wolfram <wfischer AT bnl.gov>; Minty, Michiko <minty AT bnl.gov>; Drees, Angelika <drees AT bnl.gov>; Huang, Haixin <huanghai AT bnl.gov>
Subject: Re: [Sphenix-run-l] Fwd: [request for input] sPHENIX crossing angle with PP in Run24

 

Hi Kin,

 

Here's the plot along with some key messages:

1. The reduction in luminosity for polarized protons is milder compared to AuAu, primarily because of the shorter proton bunch length, resulting in a reduction factor of 4 compared to a reduction factor of 6 for AuAu with 2 mrad crossing angle.
2. Luminosity within a range of +/- 10 cm accounts for 20% of the total luminosity when there is no crossing angle.
3. When a 1 mrad crossing angle is introduced, the luminosity within +/- 10 cm is 94.0% of the luminosity without a crossing angle.
4. Similarly, with a 2 mrad crossing angle, the luminosity within +/- 10 cm is 79.4% of the luminosity without a crossing angle.

 

Chuyu Liu

Collider Accelerator Department,
Brookhaven National Lab, Upton, NY
Work: +1 631 344-4431
Cell:   +1 631 202-7823

---

From: Yip, Kin <kinyip AT bnl.gov>
Sent: Thursday, September 21, 2023 7:47 AM
To: Liu, Chuyu <cliu1 AT bnl.gov>; Hock, Kiel <khock AT bnl.gov>
Cc: Fischer, Wolfram <wfischer AT bnl.gov>; Minty, Michiko <minty AT bnl.gov>; Drees, Angelika <drees AT bnl.gov>; Huang, Haixin <huanghai AT bnl.gov>
Subject: RE: [Sphenix-run-l] Fwd: [request for input] sPHENIX crossing angle with PP in Run24

 

Yes , I think that is what Tony asks (for now at least).  

 

Kin

 

 

-------- Original message --------

From: "Liu, Chuyu" <cliu1 AT bnl.gov>

Date: 9/21/23 07:35 (GMT-05:00)

To: "Yip, Kin" <kinyip AT bnl.gov>, "Hock, Kiel" <khock AT bnl.gov>

Cc: "Fischer, Wolfram" <wfischer AT bnl.gov>, "Minty, Michiko" <minty AT bnl.gov>, "Drees, Angelika" <drees AT bnl.gov>, "Huang, Haixin" <huanghai AT bnl.gov>

Subject: Re: [Sphenix-run-l] Fwd: [request for input] sPHENIX crossing angle with PP in Run24

 

Hi Kin,

 

Sure, I can work on that. I will plot total luminosity and  +/-10 cm luminosity VS crossing angle, similar to what wolfram did before. Would that be sufficient?

 

Chuyu Liu

Collider Accelerator Department,
Brookhaven National Lab, Upton, NY
Work: +1 631 344-4431
Cell:   +1 631 202-7823

---

From: Yip, Kin <kinyip AT bnl.gov>
Sent: Wednesday, September 20, 2023 8:17 PM
To: Liu, Chuyu <cliu1 AT bnl.gov>; Hock, Kiel <khock AT bnl.gov>
Cc: Fischer, Wolfram <wfischer AT bnl.gov>
Subject: RE: [Sphenix-run-l] Fwd: [request for input] sPHENIX crossing angle with PP in Run24

 

Hello Chuyu and all,

 

As Tony asked below, do you have a way to estimate how much luminosity is inside +/- 10 cm ? 

 

You've got non-Gaussian shapes of beam profiles etc. in your simulation.   I think, you have had some knowledge of beam profiles/sizes.  Can you please do your luminosity calculations for just +/- 10 cm and give us the results ?

 

Kin

 

On 9/19/23 15:48, Anthony Frawley wrote:

Hello Kin,

 

For most of the sPHENIX physics program, the usable luminosity is from collisions inside the MVTX acceptance (z = +/- 10 cm). Increases in luminosity that occur outside the acceptance of our silicon do not help that program, but they contribute background in the TPC that is harmful.

 

It is important to understand by how much the luminosity inside z = +/- 10 cm would increase with a reduced crossing angle.

 

Best regards

Tony Frawley

---

From: Rosi Reed <rosijreed AT lehigh.edu>
Sent: Tuesday, September 19, 2023 1:22 PM
To: Yip, Kin <kinyip AT bnl.gov>
Cc: Liu, Chuyu <cliu1 AT bnl.gov>; Anthony Frawley <afrawley AT fsu.edu>; Bazilevsky, Alexander <shura AT bnl.gov>; sphenix-run-l AT lists.bnl.gov <sphenix-run-l AT lists.bnl.gov>
Subject: Re: [Sphenix-run-l] Fwd: [request for input] sPHENIX crossing angle with PP in Run24

 

Hi Kin and all,

Thanks for sharing, this was really interesting.  One thing that's not clear to me, when it is said that we aren't able to get the luminosity that we had in previous runs "after so many years", do we really understand the issue?  Is it a training issue - I  understand that a large fraction of C-AD operators up until Run 23 hadn't been around for top energy running.  Is it something in the RHIC ring itself?  AGS?  Since the luminosity is so important both to the program we can have in sPHENIX and for the EIC, I'd like to understand it a bit better.

Cheers,

Rosi

 

On Tue, Sep 19, 2023 at 10:24 AM Yip, Kin <kinyip AT bnl.gov> wrote:

Hello,

 

Thanks, Chuyu.  I’ve updated my https://bnlbox.sdcc.bnl.gov/index.php/s/9oDpcep7ZD5Ciyk ,

in case some collaborators can’t get to your sharepoint file.

 

Kin

 

From: Liu, Chuyu <cliu1 AT bnl.gov>
Sent: Tuesday, September 19, 2023 10:12 AM
To: Yip, Kin <kinyip AT bnl.gov>; Anthony Frawley <afrawley AT fsu.edu>; Bazilevsky, Alexander <shura AT bnl.gov>; sphenix-run-l AT lists.bnl.gov
Subject: Re: [Sphenix-run-l] Fwd: [request for input] sPHENIX crossing angle with PP in Run24

 

Kin,

 

I've added two more slides to the end of the presentation on projections for pp and pAu with crossing angles. Link: Crossing angle Lumi reduction.pptx

 

Chuyu Liu

Collider Accelerator Department,
Brookhaven National Lab, Upton, NY
Work: +1 631 344-4431
Cell:   +1 631 202-7823

---

From: Yip, Kin <kinyip AT bnl.gov>
Sent: Monday, September 18, 2023 11:07 AM
To: Anthony Frawley <afrawley AT fsu.edu>; Bazilevsky, Alexander <shura AT bnl.gov>; sphenix-run-l AT lists.bnl.gov <sphenix-run-l AT lists.bnl.gov>
Cc: Liu, Chuyu <cliu1 AT bnl.gov>
Subject: RE: [Sphenix-run-l] Fwd: [request for input] sPHENIX crossing angle with PP in Run24

 

Hi,

 

Our polarization experts such as Ralf Seidl and Sasha have had some email discussion about the polarization effect with crossing angles.

 

• What is at stake here? Do we have guidance from CAD on crossing angle vs maximum luminosity?

 

In the RHIC Retreat, basically, C-AD (Chuyu Liu and Wolfram Fischer) told us that what we saw ( a factor of 6-7) is “right” and real.

Their previous calculation assuming Gaussian only profile is wrong.  After the RHIC Retreat, I asked Chuyu and he

sent us this file for his new calculation :

 

https://bnlbox.sdcc.bnl.gov/index.php/s/9oDpcep7ZD5Ciyk

 

Kin

 

From: Sphenix-run-l <sphenix-run-l-bounces AT lists.bnl.gov> On Behalf Of Anthony Frawley
Sent: Monday, September 18, 2023 10:41 AM
To: Bazilevsky, Alexander <shura AT bnl.gov>; sphenix-run-l AT lists.bnl.gov
Subject: Re: [Sphenix-run-l] Fwd: [request for input] sPHENIX crossing angle with PP in Run24

 

Hello Stefan,

 

This seems like a very important question that we should make sure to get right.

 

What is at stake here? Do we have guidance from CAD on crossing angle vs maximum luminosity?

 

Thanks

Tony

 

---

From: Sphenix-run-l <sphenix-run-l-bounces AT lists.bnl.gov> on behalf of Alexander Bazilevsky <shura AT bnl.gov>
Sent: Monday, September 18, 2023 10:21 AM
To: sphenix-run-l AT lists.bnl.gov <sphenix-run-l AT lists.bnl.gov>
Subject: Re: [Sphenix-run-l] Fwd: [request for input] sPHENIX crossing angle with PP in Run24

 

Hi Stefan,

Ralf has calculations of the expected impact of the cross angle on polarization. I haven't seen any calculations like that from STAR people. So, they are talking qualitatively (yes, the effect may be there), but we are talking quantitatively (the effect is small).
I think Ralf may give more details and/or correct my understanding.

Sasha.

On 9/18/23 10:09 AM, Stefan Bathe wrote:

Hi All,

 

Please see Kiel’s message below.  I don’t feel qualified to answer this by myself.  So I’m asking for input.  But I’d like to turn this around within 24 h.

 

I think the answer to the question why we are not concerned about running polarized protons with a crossing angle is quantitative:  in principle it’s a concern, but quantitatively we think we can live with it. But I don’t know what the actual evidence is.

 

I think there’s no reasonable chance we’d switch to a zero crossing angle except in a disaster scenario (luminosity so low that we don’t need a crossing angle; or no tracking).

 

Best,

Stefan

 

 

- 

---------------------------------------------------------------------------------
Stefan Bathe

Professor of Physics
Baruch College, CUNY
and RIKEN Visiting Scientist

Baruch:                                     BNL:
17 Lexington Ave                      Bldg. 510
office 940                                  office 2-229
phone 646-660-6272                phone 631-344-8490
----------------------------------------------------------------------------------

 

 

 

Begin forwarded message:

 

From: "Hock, Kiel" <khock AT bnl.gov>

Subject: sPHENIX crossing angle with PP in Run24

Date: September 18, 2023 at 09:20:48 EDT

To: "stefan.bathe AT baruch.cuny.edu" <stefan.bathe AT baruch.cuny.edu>, "Bathe, Stefan" <bathe AT bnl.gov>

Cc: "Fischer, Wolfram" <wfischer AT bnl.gov>, "Minty, Michiko" <minty AT bnl.gov>, "Schoefer, Vincent" <schoefer AT bnl.gov>, "Gu, Xiaofeng" <xgu AT bnl.gov>

 

* This email originates from a sender outside of CUNY. Verify the sender before replying or clicking on links and attachments. *

Hi Stefan,

 

To support intensities at RHIC above 2.1e11 protons/bunch, a crossing angle at sPHENIX is needed. 

Is there a reason why sPHENIX is not concerned about having a crossing angle for polarized protons where STAR is?

Is there a possibility that sPHENIX will change to a zero crossing angle during the run, which would limit the maximum intensity?

 

Thank you,

 

Kiel

 

 

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Alexander Bazilevsky

Brookhaven National Laboratory, Bldg. 510D, 2-232

Upton, NY 11973 Tel: 631-344-3712

Email: shura AT bnl.gov

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Rosi Reed
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Lehigh University
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Rosi Reed
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Lehigh University
(610)758-3907
16 Memorial Drive East Office 406
Bethlehem, PA 18015

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