<html><body><div style="font-family: arial,helvetica,sans-serif; font-size: 12pt; color: #000000"><div>Marco,</div><div>I attached the deuterium source spectrum of the lamp that we are using for the reflectivity test.</div><div>As you see the intensity of our lamp is order of magnitude HIGHER at low wavelength.</div><div><br></div><div>Regards,</div><div>Valery</div><div><br data-mce-bogus="1"></div><div><br></div><hr id="zwchr" data-marker="__DIVIDER__"><div data-marker="__HEADERS__"><blockquote style="border-left:2px solid #1010FF;margin-left:5px;padding-left:5px;color:#000;font-weight:normal;font-style:normal;text-decoration:none;font-family:Helvetica,Arial,sans-serif;font-size:12pt;" data-mce-style="border-left: 2px solid #1010FF; margin-left: 5px; padding-left: 5px; color: #000; font-weight: normal; font-style: normal; text-decoration: none; font-family: Helvetica,Arial,sans-serif; font-size: 12pt;"><b>From: </b>"mirazita" <Marco.Mirazita@lnf.infn.it><br><b>To: </b>dsg-rich@jlab.org<br><b>Sent: </b>Thursday, July 20, 2017 9:13:40 AM<br><b>Subject: </b>Re: [Dsg-rich] Reflectivity test station - alignment tests<br></blockquote></div><div data-marker="__QUOTED_TEXT__"><blockquote style="border-left:2px solid #1010FF;margin-left:5px;padding-left:5px;color:#000;font-weight:normal;font-style:normal;text-decoration:none;font-family:Helvetica,Arial,sans-serif;font-size:12pt;" data-mce-style="border-left: 2px solid #1010FF; margin-left: 5px; padding-left: 5px; color: #000; font-weight: normal; font-style: normal; text-decoration: none; font-family: Helvetica,Arial,sans-serif; font-size: 12pt;">Hi Tyler,<br>thank you for the data.<br>I attached some analysis of the these data.<br>The phodiode readout variations are much bigger than yesterday, but at <br>the end I estimated a systematic uncertainty on the reflectivity of <br>about +/-2% above 400 nm.<br>This is acceptable.<br>At lower wavelengths, the variations are bigger, but that's because the <br>intensity of the lamp is order of magnitudes smaller.<br><br>It would be nice if you could redo the same series of measurements on <br>one of the carbon fiber samples.<br><br>Marco<br><br><br>Il 2017-07-19 22:56 Tyler Lemon ha scritto:<br>> Hello,<br>> <br>> Attached is an Excel sheet containing the results from today's<br>> alignment tests of the reflectivity tests station. The sheet contains<br>> the three data sets for separate calibration and reflectivity tests of<br>> the control mirror. After the three sets of results, there are<br>> statistics showing the mean photodiode currents, reflectivity, and<br>> percent error for a wavelength.<br>> <br>> The procedure for taking each measurements was:<br>> <br>> 1.) Align test station to take calibration run.<br>> <br>> 2.) Take calibration run.<br>> <br>> 3.) Re-align test station to measure mirror.<br>> <br>> 4.) Take mirror measurement run.<br>> <br>> Between measurements, we noted that the lamp power remained at 10.65V<br>> and 3.84A. We did not turn the lamp or picoampmeter off between<br>> measurements.<br>> <br>> The calculations at the end of the data show that there is a higher<br>> error of all measurements compared to yesterday's tests when the test<br>> station was not modified between measurements. Yesterday, the errors<br>> for calibrations were under 1%. Today, the errors for calibrations<br>> were about 6%. There are some exceptions at smaller wavelengths (300nm<br>> - 400nm) where the error for the calibration is greater.<br>> <br>> The calculations also show that the control mirror's reflectivity<br>> measurements had an error of about 6% for most wavelengths. Again,<br>> there are some exceptions for reflectivity measurements at smaller<br>> wavelengths (300nm - 420nm) where the error for the reflectivity was<br>> greater. One major exception was that the reflectivity measurement at<br>> 420 nm had an error of ~20%. This measurement is highlighted in orange<br>> in the table.<br>> <br>> In conclusion, today's results further support that the main source of<br>> error in the test station is in how repeatable the test station<br>> optics's alignment is between data runs.<br>> <br>> Best regards,<br>> <br>> Tyler<br>> <br>> <br>> _______________________________________________<br>> Dsg-rich mailing list<br>> Dsg-rich@jlab.org<br>> https://mailman.jlab.org/mailman/listinfo/dsg-rich<br>_______________________________________________<br>Dsg-rich mailing list<br>Dsg-rich@jlab.org<br>https://mailman.jlab.org/mailman/listinfo/dsg-rich<br></blockquote></div></div></body></html>