<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body style="overflow-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;">Hi all,<div><br></div><div>While I was at the lab I managed to speak to a few people. I attempt a summary of where we stand and what remains to be done but please everybody feel free to weigh in if I get something wrong.</div><div><br></div><div>Regarding decoder board:</div><div><ul class="MailOutline"><li>Ken and Sean looked at the data coming out of the decoder board but it looks like there is some issue. It seems to output an error code instead of the desired data.</li><li>Mark has checked the board in the past. The signals should not depend on the beam being on. That was a hypothesis to explain the weird decoder board output.</li><li>Sergey is in contact with people from Hall B who also have such a decoder board. He assumes it will need some reconfiguration in the DAQ but doesn’t think he will have time for it before the run starts. This is now our highest priority.</li></ul><div>Action items:</div><div><ul class="MailOutline"><li>Sergey, please check the configuration as soon as possible </li><li>Ken, please check if the test runs we took with the decoder board also contain all the information for the “regular” analysis with delayed helicity. This would be a fallback option, if we can’t get the board to work properly.</li></ul></div><div><br></div></div><div>Regarding the 2023-01 data and REST production:</div><div><ul class="MailOutline"><li>Naomi wants to go ahead with the REST production asap.</li><li>Ken is working to finalise the algorithms to get the helicity information from the data stream.</li><li>Sean laid all the ground work to get the helicity information into the REST file (and even into the root tree format)</li><li>We came up with the following scheme:</li><ul class="MailOutline"><li>The evio data (raw data) contains the delayed helicity information and from now onwards also the prompt helicity information (we want to keep both)</li><li>During reconstruction the following is written to REST files (see JANA2 compatible branch <a href="https://github.com/JeffersonLab/halld_recon/tree/sdobbs_helicity_jana2">https://github.com/JeffersonLab/halld_recon/tree/sdobbs_helicity_jana2</a>):</li><ul class="MailOutline"><li>bool pattern_sync;</li><li>bool t_settle;</li><li>bool helicity;</li><li>bool pair_sync;</li><li>bool helicity_bad; </li></ul><li>A CCDB table will be populated that contains the overall sign of the helicity which might change depending on e.g. Wien angle or lambda half wave plate, as well as the electron beam polarisation</li><li>During an analysis launch we write above bools to the root tree</li><li>We will add a DSelector utility function that returns the helicity for each event (above helicity*overall sign from CCDB)</li><li>We will add a DSelector utility function that calculates the degree of polarisation for each beam photon</li></ul></ul><div>Action items:</div></div><div><ul class="MailOutline"><li>Ken: finalise algorithms for delayed and prompt reporting</li><li>Peter: test code to make sure it works as intended and work with Alex A. to include it in last monitoring launch before REST production</li><li>Mark: provide CCDB table with correct “calibration sign” for 2023-01 data as well as estimate for degree of electron beam polarisation (not needed before REST production)</li><li>Peter: check root tree output and write utility functions (help needed from Farah to include correction for linear polarisation)</li></ul><div><br></div></div><div>Further points regarding next run:</div><div><ul class="MailOutline"><li>Derek prepared the monitoring plugin for online monitoring, still missing: real helicity</li></ul><div>Action items:</div></div><div><ul class="MailOutline"><li>Derek: Include real helicity in monitoring as soon as Ken is done</li><li>Peter: Work with Alex A. to include the monitoring plots in RootSpy</li><li>Peter/Mark: Write instructions for shifters</li></ul><div><br></div></div><div>I hope I didn’t forget anything.</div><div><br></div><div>Thanks everybody for all your help in getting this off the ground. I have no doubt that this will be incredibly useful for the whole GlueX collaboration and enable us to do great physics beyond the alpha minus measurement.</div><div><br></div><div>Cheers,</div><div>Peter</div><div><br></div><div><br></div></body></html>