<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class="">My naive observation was that the efficiency in your curve dropped by a factor of 3 between 400 and 600, and that I thought was much sharper than I recall for typical PMTs. So, I was wondering if it is convoluted with an additional 1/lambda^2 dependence. That was my basic reaction; perhaps I am missing something obvious. <div class=""><br class=""></div><div class="">You are right that “garbage in/garbage out” depends a lot on the user. But my general concern with people much younger than me is that there is a belief that G4 gets everything right and people have stopped checking what G4 is actually doing , unlike the early days when it was super-buggy. There is a tendency to treat it like lattice QCD :) i.e. just assume that it is describing nature perfectly. Just want to register my skepticism on that front. </div><div class=""><br class=""></div><div class="">Cheers, KK<br class=""><div class=""><br class=""></div><div class=""><br class=""><div><blockquote type="cite" class=""><div class="">On Mar 20, 2017, at 5:34 PM, Wouter Deconinck <<a href="mailto:wdeconinck@wm.edu" class="">wdeconinck@wm.edu</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div dir="ltr" class="">Hi KK,<div class=""><br class=""></div><div class="">Why do you think it looks "unusual" as a QE curve? That is, in fact, the QE curve determined by Peiqing for the Electron Tube 9312WKB 5 inch PMTs used by Qweak. There's no input from Cherenkov processes in that curve at all.</div><div class=""><br class=""></div><div class="">It is very similar to the Photonis XP4500 series (XP4572) 5 inch PMTs used by G0, BLAST, and now the SHMS Gas Cherenkov. (What's missing is the borosilicate glass in front of the cathode, which is modeled separately in Qweak and lowers the cutoff to 250 nm. For the MOLLER pion detector I didn't assume we'd get fancy PMTs windows, just lime glass, so the cut-off is different in the figs below.)</div><div class=""><br class=""></div><div class="">Here's the ET brochure figure, the relevant line is (basically) W: </div><div class=""><br class=""></div><div class=""><span id="cid:ii_15aed9aa159fdfd5"><image.png></span><br class=""></div><div class=""><br class=""></div><div class="">Since QE = radiant sensitivity / wavelength, you should look at the angled y-axis values. That introduces a sharper cut-off with increasing wavelength (1/lambda).</div><div class=""><br class=""></div><div class="">Anyway, the QE(lambda) is probably the most justified choice in the entire pion detector. Everything else, from size to angles to materials, is still undetermined. Let's focus on that instead of the PMT QE curve. </div><div class=""><br class=""></div><div class="">Finally, I find that geant4 is somewhere on the continuum between "general instincts" and data ;-) It's probably somewhere between geant3 and data :-) It is the best collection of physics modeling we have, but it is still a computer program: garbage in, garbage out. In my experience, the garbage is more likely to come from the user, not from geant4 :-)</div><div class=""><br class=""></div><div class="">Cheers,</div><div class="">Wouter</div><div class="gmail_extra"><br class=""></div><div class="gmail_extra"><br class=""><div class="gmail_quote">On Mon, Mar 20, 2017 at 4:55 PM, Krishna Kumar <span dir="ltr" class=""><<a href="mailto:krishna.kumar@stonybrook.edu" target="_blank" class="">krishna.kumar@stonybrook.edu</a>></span> wrote:<br class=""><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="word-wrap:break-word" class=""><span class="">Okay, so the efficiency curve vs Lambda may or may not make sense. If it is the efficiency curve due to photocathode QE, then that curve is unusual. If it is the 1/lambda^2 cherenkov distribution, then there is a cutoff below 250 nm. Perhaps this is the product of the two? That would perhaps make sense, but then it would be good, as a cross-check, to look at both curves (QE curve and raw cherenkov distribution) individually.<div class=""><br class=""></div><div class="">My general instinct is that if one doesn’t drill down into Geant and ensure that the physics makes sense, we are liable to get burned….</div></span><div class=""><br class=""><div class="">Cheers, KK</div><div class=""><br class=""><div class=""><blockquote type="cite" class=""><span class=""><div class="">On Mar 20, 2017, at 4:47 PM, Wouter Deconinck <<a href="mailto:wdeconinck@wm.edu" target="_blank" class="">wdeconinck@wm.edu</a>> wrote:</div><br class="m_-7468237338375259032Apple-interchange-newline"></span><div class=""><div dir="ltr" class=""><span class="">Hi KK,<div class=""><br class=""></div><div class="">Sorry, I may not have been very clear about this. This is the PMT efficiency curve that is an INPUT to the simulation. It has nothing to do with the lucite or air emission or absorption spectrum. But, it does mean that any photon energy spectrum at the photocathode will be convoluted with this (can be taken out trivially, of course, for any new simulations).</div><div class=""><br class=""></div><div class="">The absorption spectrum for lucite is INPUTs as well (although to be fair all previous results were obtained with a fixed absorption length of 1 m to cut down on infinitely bouncing rays). Here's what we'd use for a more realistic lucite simulation.</div><div class=""><br class=""></div></span><div class=""><span id="m_-7468237338375259032cid:ii_15aed740d886a8c0" class=""><image.png></span><br class=""></div><div class=""><div class="h5"><div class=""><br class=""></div><div class="">I think technically this data is for quartz, not lucite, but it's qualitatively similar to lucite data I did find but didn't digitize (in particular sharp transmission cut-off below 350 nm).<br class=""></div><div class=""><br class=""></div><div class="">As for air, we do not include any optical absorption currently (though we do include Cherenkov radiation, n = 1.000292).</div><div class=""><br class=""></div><div class="">Cheers,<div class="">Wouter</div></div></div></div></div><div class=""><div class="h5"><div class="gmail_extra"><br class=""><div class="gmail_quote">On Mon, Mar 20, 2017 at 4:19 PM, Krishna Kumar <span dir="ltr" class=""><<a href="mailto:krishna.kumar@stonybrook.edu" target="_blank" class="">krishna.kumar@stonybrook.edu</a>></span> wrote:<br class=""><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div style="word-wrap:break-word" class=""><span class="">
Okay, this is pretty conservative. We can do better than this between 200 and 300 if it becomes an issue, but you might decide you don’t need it, which will save us money. I wonder why it cuts off though? If you didn’t explicitly put in a photocathode QE curve,
what physics in G4 cuts it off? If it is gas physics, it would start cutting off below 200, not below 250. Is the scintillator material transparent below 250 or not? I don’t recall this from my prior experience. KK
</span><div class=""><br class="">
<div class="">
<blockquote type="cite" class=""><span class="">
<div class="">On Mar 20, 2017, at 4:08 PM, Wouter Deconinck <<a href="mailto:wdeconinck@wm.edu" target="_blank" class="">wdeconinck@wm.edu</a>> wrote:</div>
<br class="m_-7468237338375259032m_1485888386441672621Apple-interchange-newline">
</span><div class="">
<div dir="ltr" class=""><span class="">Hi all,
<div class=""><br class="">
</div>
<div class="">Since it came up in MOLLER pion detector simulation discussions last Friday, here is the efficiency curve of the photocathode in the pion simulations. UV photons are definitely not registered below about 230 nm.</div>
</span><div class=""><br class="">
<div class=""><span id="m_-7468237338375259032m_1485888386441672621cid:ii_15aed4ecf4075e5c" class=""><image.png></span><br class="">
</div>
</div><div class=""><div class="m_-7468237338375259032h5">
<div class=""><br class="">
</div>
<div class="">Since someone will ask: from the course code I think it uses linear interpolation, constant value extrapolation outside the given range. So it'd make sense to add a zero efficiency point on both sides of the range.</div>
<div class=""><br class="">
</div>
<div class="">Cheers,</div>
<div class="">Wouter</div>
</div></div></div><div class=""><div class="m_-7468237338375259032h5">
<div class="gmail_extra"><br class="">
<div class="gmail_quote">On Tue, Mar 14, 2017 at 3:20 PM, Kurtis Bartlett <span dir="ltr" class="">
<<a href="mailto:kdbartlett@email.wm.edu" target="_blank" class="">kdbartlett@email.wm.edu</a>></span> wrote:<br class="">
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div dir="ltr" class=""><span style="font-size:12.8px" class="">Hello Everyone,</span>
<div style="font-size:12.8px" class=""><br class="">
</div>
<div style="font-size:12.8px" class="">As a reminder to the members of the <span class="m_-7468237338375259032m_1485888386441672621m_4261606059289500566m_-4991608047743486789m_2145963482046753178m_-3216089366405490180m_6242814976674702406m_6383061932988912735gmail-m_2175965128871661572gmail-m_-4121694774762064494gmail-il"><span class="m_-7468237338375259032m_1485888386441672621m_4261606059289500566m_-4991608047743486789m_2145963482046753178m_-3216089366405490180m_6242814976674702406il"><span class="m_-7468237338375259032m_1485888386441672621m_4261606059289500566m_-4991608047743486789m_2145963482046753178m_-3216089366405490180il"><span class="m_-7468237338375259032m_1485888386441672621m_4261606059289500566m_-4991608047743486789m_2145963482046753178il"><span class="m_-7468237338375259032m_1485888386441672621m_4261606059289500566m_-4991608047743486789il"><span class="m_-7468237338375259032m_1485888386441672621m_4261606059289500566il">MOLLER</span></span></span></span></span></span> <span class="m_-7468237338375259032m_1485888386441672621m_4261606059289500566m_-4991608047743486789m_2145963482046753178m_-3216089366405490180m_6242814976674702406m_6383061932988912735gmail-m_2175965128871661572gmail-m_-4121694774762064494gmail-il"><span class="m_-7468237338375259032m_1485888386441672621m_4261606059289500566m_-4991608047743486789m_2145963482046753178m_-3216089366405490180m_6242814976674702406il"><span class="m_-7468237338375259032m_1485888386441672621m_4261606059289500566m_-4991608047743486789m_2145963482046753178m_-3216089366405490180il"><span class="m_-7468237338375259032m_1485888386441672621m_4261606059289500566m_-4991608047743486789m_2145963482046753178il"><span class="m_-7468237338375259032m_1485888386441672621m_4261606059289500566m_-4991608047743486789il"><span class="m_-7468237338375259032m_1485888386441672621m_4261606059289500566il">Pion</span></span></span></span></span></span> <span class="m_-7468237338375259032m_1485888386441672621m_4261606059289500566m_-4991608047743486789m_2145963482046753178m_-3216089366405490180il">Background</span>/Det<wbr class="">ector
working group, there will be a meeting this week on Friday at 9am.</div>
<div style="font-size:12.8px" class=""><br class="">
</div>
<div style="font-size:12.8px" class=""><span style="font-size:12.8px" class="">The agenda for the meeting can be found on the </span><span class="m_-7468237338375259032m_1485888386441672621m_4261606059289500566m_-4991608047743486789m_2145963482046753178m_-3216089366405490180m_6242814976674702406m_6383061932988912735gmail-m_2175965128871661572gmail-m_-4121694774762064494gmail-m_9088376801859300875gmail-il" style="font-size:12.8px"><span class="m_-7468237338375259032m_1485888386441672621m_4261606059289500566m_-4991608047743486789m_2145963482046753178m_-3216089366405490180m_6242814976674702406il"><span class="m_-7468237338375259032m_1485888386441672621m_4261606059289500566m_-4991608047743486789m_2145963482046753178m_-3216089366405490180il"><span class="m_-7468237338375259032m_1485888386441672621m_4261606059289500566m_-4991608047743486789m_2145963482046753178il"><span class="m_-7468237338375259032m_1485888386441672621m_4261606059289500566m_-4991608047743486789il"><span class="m_-7468237338375259032m_1485888386441672621m_4261606059289500566il">MOLLER</span></span></span></span></span></span><span style="font-size:12.8px" class=""> wiki:</span></div>
<div style="font-size:12.8px" class=""><span style="font-size:12.8px" class=""></span><br class="">
<a href="https://hallaweb.jlab.org/wiki/index.php/MOLLER_Pion_Background_Meeting_Friday%2C_March_17%2C_2017_9:00am_EST" target="_blank" class="">https://hallaweb.jlab.org/wiki<wbr class="">/index.php/MOLLER_Pion_Backgro<wbr class="">und_Meeting_Friday%2C_March_17<wbr class="">%2C_2017_9:00am_EST</a><br class="">
<br class="">
Feel free to add any other points of business to the wiki.</div>
<div style="font-size:12.8px" class="">
<div style="font-size:12.8px" class="">
<div style="font-size:12.8px" class=""><br class="">
</div>
<div style="font-size:12.8px" class="">
<div style="font-size:12.8px" class="">Here is the Bluejeans call information:</div>
<div style="font-size:12.8px" class=""><br class="">
</div>
<div style="font-size:12.8px" class="">URL: <a href="https://bluejeans.com/624029893" target="_blank" class="">https://bluejeans.com/624<wbr class="">029893</a></div>
<div style="font-size:12.8px" class=""><br class="">
</div>
<div style="font-size:12.8px" class="">Phone Number: <a href="tel:1-888-240-2560" value="+18882402560" target="_blank" class="">1-888-240-2560</a></div>
<div style="font-size:12.8px" class=""><br class="">
</div>
<div style="font-size:12.8px" class="">Meeting ID: 624029893</div>
<div style="font-size:12.8px" class=""><br class="">
</div>
<div style="font-size:12.8px" class="">Hope to see everyone there.</div>
<div style="font-size:12.8px" class=""><br class="">
</div>
<div style="font-size:12.8px" class="">Cheers,</div>
<div style="font-size:12.8px" class=""><br class="">
</div>
<div style="font-size:12.8px" class="">Kurtis</div>
</div>
</div>
</div>
<div class="m_-7468237338375259032m_1485888386441672621m_4261606059289500566yj6qo m_-7468237338375259032m_1485888386441672621m_4261606059289500566ajU">
<div id="m_-7468237338375259032m_1485888386441672621m_4261606059289500566:1fm" class="m_-7468237338375259032m_1485888386441672621m_4261606059289500566ajR"><img class="m_-7468237338375259032m_1485888386441672621m_4261606059289500566ajT" src="https://ssl.gstatic.com/ui/v1/icons/mail/images/cleardot.gif"></div>
</div>
<span class="m_-7468237338375259032m_1485888386441672621HOEnZb"><font color="#888888" class=""><br clear="all" class="">
<br class="">
-- <br class="">
<div class="m_-7468237338375259032m_1485888386441672621m_4261606059289500566gmail_signature" data-smartmail="gmail_signature">
<div dir="ltr" class="">Kurtis D. Bartlett<br class="">
<br class="">
<div class="">PhD. Research Candidate </div>
<div class="">College of William and Mary Physics Department<br class="">
<a href="mailto:kdbartlett@email.wm.edu" target="_blank" class="">kdbartlett@email.wm.edu</a></div>
</div>
</div>
</font></span></div>
<br class="">
______________________________<wbr class="">_________________<br class="">
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<br class="">
</blockquote>
</div>
<br class="">
<br clear="all" class="">
<div class=""><br class="">
</div>
-- <br class="">
<div class="m_-7468237338375259032m_1485888386441672621gmail_signature" data-smartmail="gmail_signature">
<div dir="ltr" class="">
<div class="">Wouter Deconinck<br class="">
Assistant Professor of Physics<br class="">
College of William & Mary<br class="">
Office: Small Hall 343D<br class="">
Phone: <a href="tel:(757)%20221-3539" value="+17572213539" target="_blank" class="">(757) 221-3539</a></div>
<div class=""><br class="">
</div>
<div class="">E<span style="font-size:12.8px" class="">mails sent to this address are subject to requests for public review under the Virginia Freedom of Information Act.</span></div>
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</blockquote>
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</div>
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</blockquote></div><br class=""><br clear="all" class=""><div class=""><br class=""></div>-- <br class=""><div class="m_-7468237338375259032gmail_signature" data-smartmail="gmail_signature"><div dir="ltr" class=""><div class="">Wouter Deconinck<br class="">Assistant Professor of Physics<br class="">College of William & Mary<br class="">Office: Small Hall 343D<br class="">Phone: <a href="tel:(757)%20221-3539" value="+17572213539" target="_blank" class="">(757) 221-3539</a></div><div class=""><br class=""></div><div class="">E<span style="font-size:12.8px" class="">mails sent to this address are subject to requests for public review under the Virginia Freedom of Information Act.</span></div></div></div>
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<a href="mailto:Moller_pion_bg@jlab.org" class="">Moller_pion_bg@jlab.org</a><br class="">
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<br class=""></blockquote></div><br class=""><br clear="all" class=""><div class=""><br class=""></div>-- <br class=""><div class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr" class=""><div class="">Wouter Deconinck<br class="">Assistant Professor of Physics<br class="">College of William & Mary<br class="">Office: Small Hall 343D<br class="">Phone: (757) 221-3539</div><div class=""><br class=""></div><div class="">E<span style="font-size:12.8px" class="">mails sent to this address are subject to requests for public review under the Virginia Freedom of Information Act.</span></div></div></div>
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