From: Zhangbu Xu xzb@bnl.gov
Subject: Re: Timing Integration Discussion at Collaboration Meeting
Date: July 8, 2025 at 10:21:28 AM EDT
To: "Landgraf, Jeffery M." jml@bnl.gov
Cc: Benedikt Zihlmann zihlmann@jlab.org, Satoshi Yano satoshi.yano@cern.ch, "Ye, Zhenyu" zye@bnl.gov, David Abbott abbottd@jlab.org, Fernando Barbosa barbosa@jlab.org
Hi, Jeff and Satoshi:
That is a good question.
In addition to T0 impact, we have also tried different methods:
Startless TOF when there are multiple particles resulting the collision
We also studied the exclusive vector meson production with two tracks and a not-so-good T0.
These are some of the solutions to the issues.
Satoshi has done a study on single particle resolution requirement with T0 estimates.
All these are case-by-case depending on the physics measurements.
The requirements are quite different.
The most stringent constraint is how much overlap is required between TOF and hpDIRC.
In terms of item 3, I propose that we select pions at low momentum, which we should be able to cleanly
Separate from other particles and use measured pion mass from TOF to track any slow phase drifts.
Zhangbu
On Jul 7, 2025, at 8:16 PM, Landgraf, Jeffery M. jml@bnl.gov wrote:
Hello,
I'm really sorry that this is coming so late, but I'd like to have a discussion regarding the timing requirements at the collaboration meeting. I think we really need to address this as an integration issue,,, There are a lot of requirements ranging from 20 ps - 40 ps quoted as requirements for the TOF detectors but we have a lot contributions from various components, many of which are on the order of 20-30 ps. These aren't just electronics, they also include the T0 determination and calibrations of the TOF detectors.
The requirement is also much more complex than we typically discuss, as the time that matters is the collision time to the measured time in the detector, whereas the timing resolutions of the electronics usually quote the jitter, even though there will significant slow timing shifts due to temperature variations both in the fiber path and in the detector itself.
We also have potential resources that could be brought into play if needed, and if we have smart ideas. For example, the BPMs get beam induced signal that can be brought out. This is good to the sub-picosecond level, but would suffer the same sort of drift if we bring it out of the hall, so we'd need some new concept to make use of it.
Is there anyone who could give a summary from the TOF side? Specifically, I'd want some idea about:
The requirement/impact of timing resolution for the physics analysis
The timing impact of the T0 determination
Whether it is (or might be) possible to track slow phase drifts of the clock (due to temperature) using calibrations
This would likely be during the Thursday afternoon E&DAQ session.
Thanks,
Jeff
