sPHENIX discussion of the superconducting solenoid

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

Hi,

 

Thank you for your finding !  I/we really appreciate it.

 

• in short, yes, the vertical axis is swapped, but there might be a minor

 

That’s the most important part 😊

 

Please take your time.  There is in principle no rush.  It’s important to get it right.

 

Thanks again !

 

Kin

 

From: Nicola Pacifico <Nicola.Pacifico AT cern.ch>
Sent: Friday, November 18, 2022 4:32 PM
To: Yip, Kin <kinyip AT bnl.gov>; Haggerty, John <haggerty AT bnl.gov>; Pritindra Bhowmick <pritindra.bhowmick AT cern.ch>
Subject: RE: Is it possible to swap the direction of the vertical component

 

Hello,

 

Just to let you know that the issue seems to be found. I get now plots that at least make sense for a solenoid. I don't want though to send you one more batch of erroneous data, so I'll revise the thing with a fresh mind over the weekend and send you the updated files on Monday (however, in short, yes, the vertical axis is swapped, but there might be a minor correction also on the other two components due to the same error being present not only on the phi rotation but also on the bench alignment rotation, however we are talking about ~0.1% difference for the latter).

 

Have a nice weekend!

 

Cheers,

Nicola

 

 

----------------------------------------------------------------

Nicola Pacifico

bat. 70-R-008

CERN - European Organization for Nuclear Research

CH-1211, Geneva 23

 

e-mail: nicola.pacifico AT cern.ch

mobile: +41 75 411 8218

---

From: Yip, Kin [kinyip AT bnl.gov]
Sent: 18 November 2022 13:18
To: Nicola Pacifico; John Haggerty; Pritindra Bhowmick
Subject: RE: Is it possible to swap the direction of the vertical component

Hi,

 

Thanks for your replies.  I saw your other email and I hope you find something ...By the way, so far, I am working on the Rough mapping in full field.

 

> with the plots for the simulated vs measured data for 

> the vertical coordinate? 

 

Like what I did for John, I used your exact coordinates (x,y,z) (converted to our sPHENIX system z→y, -y → z), and after Opera loaded the previously processed Opera (.op3) , we give the 41760 set of coordinates to Opera which would find their (Bx, By, Bz) for us, so that we don't need to extrapolate further.

 

The horizontal Bx difference is :

https://www.c-ad.bnl.gov/kinyip/download/Bx_diff.gif

 

Which is similar to the "modified" difference in B in vertical direction, after I swapped B(vertical) .

 

Kin

 

 

 

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

From: Nicola Pacifico <Nicola.Pacifico AT cern.ch>

Date: 11/18/22 6:45 AM (GMT-05:00)

To: "Yip, Kin" <kinyip AT bnl.gov>, "Haggerty, John" <haggerty AT bnl.gov>, Pritindra Bhowmick <pritindra.bhowmick AT cern.ch>

Subject: RE: Is it possible to swap the direction of the vertical component

 

Hi Kin,

I had a look at our transform code with your comment in mind, and I couldn't really find anything suggesting a swap. This doesn't mean that it's not there though, maybe hidden in something else than the rotation matrices. Could you provide me, in addition with the plot of the difference, with the plots for the simulated vs measured data for the vertical coordinate? Also, I guess you don't see the same swap on the horizontal coordinate, or you would have mentioned it...

I'll keep looking into this.

Cheers,
Nicola

----------------------------------------------------------------
Nicola Pacifico
bat. 70-R-008
CERN - European Organization for Nuclear Research
CH-1211, Geneva 23

e-mail: nicola.pacifico AT cern.ch
mobile: +41 75 411 8218

________________________________________
From: Yip, Kin [kinyip AT bnl.gov]
Sent: 18 November 2022 02:22
To: Nicola Pacifico; John Haggerty
Subject: Is it possible to swap the direction of the vertical component

Dear Nicola and Pri,

I wonder whether it’s possible that you swap the sign of the vertical component (your Bz and z) ?
Is up (pointing to the sky) +ve/positive ?  { I attached the coordination discussion of John's at the bottom. }

I made a plot of difference of the Bvertical (which is your Bz) with our Opera simulation results.
The difference for Bvertical seems rather large (larger than others) :
https://www.c-ad.bnl.gov/kinyip/download/Bvertical_diff.gif

If I swapped your Bvertical (to -Bvertical) and then made the difference plot again, it’s much smaller :
https://www.c-ad.bnl.gov/kinyip/download/modified_Bvertical_diff.gif

You have two sets of NMR probes (pointing oppositely).  I wonder whether it’s possible that you
might have swapped by mistake/accident ?

A speculation of mine …

Kin


-----Original Message-----
From: Nicola Pacifico <Nicola.Pacifico AT cern.ch>
Sent: Wednesday, November 9, 2022 4:21 PM
To: Haggerty, John <haggerty AT bnl.gov>
Cc: Yip, Kin <kinyip AT bnl.gov>
Subject: RE: Which way is up?

Hi John,

That sounds right...

Cheers,
Nicola

----------------------------------------------------------------
Nicola Pacifico
bat. 70-R-008
CERN - European Organization for Nuclear Research
CH-1211, Geneva 23

e-mail: nicola.pacifico AT cern.ch
mobile: +41 75 411 8218

________________________________________
From: John Haggerty [haggerty AT bnl.gov]
Sent: 09 November 2022 21:47
To: Nicola Pacifico
Cc: Kin Yip
Subject: Which way is up?

Nicola,

Just to be sure we're all on the same page when we compare fields, when
you say "my frame" you mean the surveyor's frame, and that means

x points west
y points south (the chimney is on the south)
z points up

(where we usually stand to enter the bore is the north side of the
detector, so west is on your right when you face the magnet).

The experiment's coordinate system is

x points west
y points up
z points north

so

survey x is our x
survey y is our -z
survey z is our y