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Hi All,</div>
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Given how serious this problem potentially is for the hpDIRC, I'm still a bit puzzled why no one from the experts looked into a feasibility of PID event reconstruction with it without using tracking information for any other purposes but a track-to-ring matching.</div>
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I'm not talking about writing a full reconstruction suite. Just a conceptual consideration with a simple outcome: the approach is feasible (then one can think about estimates and / or implementation) or outright excluded (then minimizing the material budget
is of a paramount importance). From a technical perspective, it is a matter of systematically shifting reconstructed track parameters by few mrad, and checking whether a chi^2-like measure of how well a PID hypothesis matches the measured hits changes substantially
or it does not. Big deal.</div>
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Everybody understands that if you have N points on a 2D plane, which are supposed to be distributed along a circumference of a circle of unknown radius, one can solve the problem either with or without an a priori knowledge of where the center of the circle
is. In one case you have a problem with 2N-1 degrees of freedom. In the other case - with 2N-3. Of course, this cannot work well if all the hits are sitting on one side of the circle. Is it really the case for hpDIRC images (which are not circles, but then
what exactly is the difference?). Otherwise, an ultimately correct hpDIRC reconstruction code may actually want to add track parameters as Lagrange multipliers with a cov. matrix given by tracking to the problem, and re-tune them along with obtaining a PID
hypothesis. My 2 cents.</div>
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Cheers,</div>
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Alexander.</div>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>From:</b> Erd108 <erd108-bounces@jlab.org> on behalf of Sourav Tarafdar <stara@jlab.org><br>
<b>Sent:</b> Wednesday, July 17, 2024 11:57 AM<br>
<b>To:</b> Kondo Gnanvo <kagnanvo@jlab.org>; Shyam Kumar <shyam055119@gmail.com><br>
<b>Cc:</b> erd108@jlab.org <erd108@jlab.org><br>
<b>Subject:</b> Re: [Erd108] [External] Re: Additional simulation request</font>
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Hi Kondo,</div>
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You are right for the momentum range for both DIRC and ToF. At momentum of >= 1 GeV is where the tracking angular resolution will help with DIRC PID , if I am not mistaken. 1-3 GeV is where the problem with multiple scattering is coming up.</div>
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best regards,</div>
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Sourav</div>
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<div id="x_divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" color="#000000" style="font-size:11pt"><b>From:</b> Kondo Gnanvo <kagnanvo@jlab.org><br>
<b>Sent:</b> Wednesday, July 17, 2024 11:53 AM<br>
<b>To:</b> Sourav Tarafdar <stara@jlab.org>; Shyam Kumar <shyam055119@gmail.com><br>
<b>Cc:</b> Matthew Posik <posik@temple.edu>; Gnanvo, Kondo (kg6cq) <kg6cq@virginia.edu>; erd108@jlab.org <erd108@jlab.org><br>
<b>Subject:</b> Re: [Erd108] [External] Re: Additional simulation request</font>
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<div dir="ltr">One quick question, </div>
<div dir="ltr">Is the tracking needed for PID with DIRC at low momenta (<1GeV) or rather a higher momenta (6GeV) </div>
<div dir="ltr">I would expect the ToF to basically cover the low momenta region </div>
<div dir="ltr">Best regards </div>
<div dir="ltr">Kondo </div>
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<div id="x_x_divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" color="#000000" style="font-size:11pt"><b>From:</b> Sourav Tarafdar <stara@jlab.org><br>
<b>Sent:</b> Wednesday, July 17, 2024 11:48:46 AM<br>
<b>To:</b> Shyam Kumar <shyam055119@gmail.com><br>
<b>Cc:</b> Matthew Posik <posik@temple.edu>; Kondo Gnanvo <kagnanvo@jlab.org>; Gnanvo, Kondo (kg6cq) <kg6cq@virginia.edu>; erd108@jlab.org <erd108@jlab.org><br>
<b>Subject:</b> Re: [Erd108] [External] Re: Additional simulation request</font>
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Thanks Shyam. The final numbers with 5% ToF material budget will be helpful in justifying not to increase the ToF material budget further. It will also affect the electron line shape at EMCAL (but anyway, EMCAL is not my or this mailing list main concern).
At some point one need to see if one can do better than current 3.5 mrad based on Matt's study in reality to improve DIRC performance (may be not at the level of "high performance" )but reasonable pi/K separation (again that has to come from PID group).</div>
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Best regards,</div>
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Sourav</div>
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<div id="x_x_x_divRplyFwdMsg" dir="ltr"><span style="font-family:Calibri,sans-serif; font-size:11pt; color:rgb(0,0,0)"><b>From:</b> Shyam Kumar <shyam055119@gmail.com><br>
<b>Sent:</b> Wednesday, July 17, 2024 11:25 AM<br>
<b>To:</b> Sourav Tarafdar <stara@jlab.org><br>
<b>Cc:</b> Matthew Posik <posik@temple.edu>; Kondo Gnanvo <kagnanvo@jlab.org>; Gnanvo, Kondo (kg6cq) <kg6cq@virginia.edu>; erd108@jlab.org <erd108@jlab.org><br>
<b>Subject:</b> Re: [Erd108] [External] Re: Additional simulation request</span>
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<div style="direction:ltr">Dear Matt and Sourav,</div>
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<div style="direction:ltr">The idea of Matt of the formation of fast tracklets can help there. As I understand, it may help but will need to do some studies.</div>
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<div style="direction:ltr">Regards,</div>
<div style="direction:ltr">Shyam</div>
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