sPHENIX MAPS tracker discussion

[Cameron Thomas Dean <cameron.dean AT cern.ch>]

Hi Ming,

Thanks for raising the concern. As far as I know, the beam has never been lost during steering (though it has been lost several times during normal physics operation).

Cheers,
Cameron

 

From: sphenix-maps-l-request AT lists.bnl.gov <sphenix-maps-l-request AT lists.bnl.gov> on behalf of "Liu, Ming Xiong" <sphenix-maps-l AT lists.bnl.gov>
Date: Tuesday, July 30, 2024 at 12:18 AM
To: hrjheng AT mit.edu <hrjheng AT mit.edu>, SPHENIX MVTX <sphenix-maps-l AT lists.bnl.gov>
Subject: Re: [[Sphenix-maps-l] ] [EXTERNAL] Updated chip occupancy comparison

Thank you Hao-Ren for the update, very nice to see with +1.5mrad, the MVTX background level is significantly less than other crossing angle.

So likely, we have less beam scarping on apertures in +1.5mrad configuration, like to follow up this with C-AD, knowing the tilted beam pipe and MVTX from ideal positions.

 

About the STAR steering – as we discussed in today’s MVTX meeting, the main concern is about the high risk of accidental beam loss that could damage the sensors.

 

Cheers,

Ming

-- 

Dr. Ming Xiong Liu

P-3 Group, MS H846

Nuclear and Particle Physics & Applications

Physics Division

 

Office: 505.667.7125

Mobile: 505.412.7396

Los Alamos National Laboratory

 

From: <sphenix-maps-l-request AT lists.bnl.gov> on behalf of Hao-Ren Jheng <hrjheng AT mit.edu>
Reply-To: Hao-Ren Jheng <hrjheng AT mit.edu>
Date: Monday, July 29, 2024 at 7:56 PM
To: SPHENIX MVTX <sphenix-maps-l AT lists.bnl.gov>
Subject: [EXTERNAL] [[Sphenix-maps-l] ] Updated chip occupancy comparison

 

Dear all,

 

I have updated the chip occupancy comparison, attached below, to include the distribution from Run 45936 with a -2 mrad crossing angle Run 49035 with a +1.5 mrad*.

Key findings are: (1) We observed a similar level of chip occupancy in -2 mrad, and (2) a significantly lower level of chip occupancy in +1.5 mrad. 

 

As discussed in today's shift change meeting, we need to address the following question:

Given that we have already turned on MVTX during the -2 mrad beam crossing to collect data with comparable chip occupancy levels, is it OK to leave MVTX ON during STAR steering?

I propose we discuss this matter in this email thread. We can then present our final decision at tomorrow's shift change meeting and update the standing order and detector summary accordingly.

 

Best,

Hao-Ren

 

* Jamie’s email on July 22 “[[Sphenix-run-l] ] special run configurations (start of 0 crossing physics data, B=0 runs, test with +1.5 mrad crossing)"