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<span style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt;">Hi Tyler,</span></div>
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<span style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt;">Thanks a lot for quick feedback!</span></div>
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<span style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt;">I think we would like to change readout to voltage, it seems to be easier to handle. One person suggested I need </span><span style="caret-color: rgb(0, 0, 0); font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; display: inline !important;">a
transimpedance amplifier for that but other said a simple resistor suffices... would it be part of the
</span><span style="caret-color:rgb(0, 0, 0);font-family:-webkit-standard;font-size:medium;display:inline !important"><span style="caret-color: rgb(0, 0, 0); font-family: Calibri, Helvetica, sans-serif; font-size: 12pt;">circuit from page 2 in spec:</span><br>
<span style="caret-color:rgb(0, 0, 0)"><a href="https://www.thorlabs.com/drawings/d3c75d389e4cb97e-309FEEC9-C8A5-6AE6-44C9015816931D45/SM1PD2A-SpecSheet.pdf" target="_blank" data-saferedirecturl="https://www.google.com/url?q=https://www.thorlabs.com/drawings/d3c75d389e4cb97e-309FEEC9-C8A5-6AE6-44C9015816931D45/SM1PD2A-SpecSheet.pdf&source=gmail&ust=1664303085408000&usg=AOvVaw0eJZaQPhYDfWRj3CsKjC49"><span style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt;">https://www.thorlabs.com/drawings/d3c75d389e4cb97e-309FEEC9-C8A5-6AE6-44C9015816931D45/SM1PD2A-SpecSheet.pdf</span><wbr><wbr><wbr><wbr></a></span></span><span style="caret-color: rgb(0, 0, 0); font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; display: inline !important;"> </span></div>
<div style="color: rgb(0, 0, 0);"><font face="-webkit-standard" size="3"><span style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt;">?</span></font></div>
<div><font face="-webkit-standard" size="3"><font size="3"><span style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt;"> It seems
</span></font><span style="caret-color: rgb(0, 0, 0); color: black; font-size: 12pt;"><span style="font-size: 12pt; margin: 0px; color: black; font-family: Calibri, Helvetica, sans-serif;">5V</span></span><font size="3"><span style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt;">
is required only for pulsed lasers and I have constant wave so we can just </span></font><span style="display: inline !important; font-family: Calibri, Helvetica, sans-serif; font-size: 12pt;">ground the cathode. Could we solder these circuits at JLab?</span><br>
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</span></span></span></font></div>
<div style="color: rgb(0, 0, 0);"><font face="-webkit-standard" size="3"><span style="caret-color:rgb(0, 0, 0)"><span style="font-size: 12pt; color: black;"><span style="caret-color: rgb(0, 0, 0); font-size: 12pt; display: inline !important; font-family: Calibri, Helvetica, sans-serif;">If
we would indeed switch to voltage, what would you suggest? And you were right about reading out two channels.</span></span></span></font></div>
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</span></span></span></font></div>
<div style="color: rgb(0, 0, 0);"><font face="-webkit-standard" size="3"><span style="caret-color:rgb(0, 0, 0)"><span style="font-size: 12pt; color: black;"><span style="caret-color: rgb(0, 0, 0); font-size: 12pt; display: inline !important; font-family: Calibri, Helvetica, sans-serif;">Cheers,</span></span></span></font></div>
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</span></span></span></font></div>
<div style="color: rgb(0, 0, 0);"><font face="-webkit-standard" size="3"><span style="caret-color:rgb(0, 0, 0)"><span style="font-size: 12pt; color: black;"><span style="caret-color: rgb(0, 0, 0); font-size: 12pt; display: inline !important; font-family: Calibri, Helvetica, sans-serif;">Greg</span></span></span></font></div>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>From:</b> Tyler Lemon <tlemon@jlab.org><br>
<b>Sent:</b> Monday, September 26, 2022 12:22 PM<br>
<b>To:</b> Grzegorz Kalicy <gkalicy@jlab.org>; dsg-eic_dirc@jlab.org <dsg-eic_dirc@jlab.org><br>
<b>Subject:</b> Re: Readout for the DIRC QA laser lab</font>
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Hi Greg,</div>
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That is something that I can help out with.</div>
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>From the specs of the photodiodes and laser, it looks like the maximum current we can expect (if everything is perfect and everything behaves ideally) is ~12 mA when the 442-nm wavelength is used. It also looks like we'll have two photodiodes to measure at
the same time during tests.</div>
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With that, something like a Keithley Model 6482, dual-channel picoammeter could be helpful.
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This picoammeter has a readout range of 1 fA - 20 mA and also has built-in GPIB and RS-232 interfaces for remote control in addition to a local readout screen.</div>
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It's base cost is ~$6,500 according to their website<br>
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Does this fit into what you're looking for in terms of "quick" and "relatively cheap"?<br>
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-Tyler<br>
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<div id="x_divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" color="#000000" style="font-size:11pt"><b>From:</b> Grzegorz Kalicy <gkalicy@jlab.org><br>
<b>Sent:</b> Monday, September 26, 2022 1:24 PM<br>
<b>To:</b> Tyler Lemon <tlemon@jlab.org><br>
<b>Subject:</b> Readout for the DIRC QA laser lab</font>
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Hi Tyler,</div>
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As I mentioned some time ago I'm trying to avoid unnecessarily complicated readout for photodiodes that we used in original setup in GSI. However, I'm struggling a bit with finding best option (quick, relatively cheap, and useable later for final automatized
setup version). Who in DSG I could reach out for advise?</div>
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Cheers,</div>
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Greg</div>
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