[Dsg-rich] Fwd: [EXTERNAL] Re: RICH prototype mirror reflectivity summary

[Patrizia Rossi]

Dear Tyler,

enjoy the appreciation express by Will Brooks for your work!!

patrizia
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# Patrizia Rossi
# Jefferson Lab
# 12000 Jefferson Avenue
# Suite 5
# Newport News VA 23606 (USA)
# e-mail: rossi at jlab.org<mailto:rossi at jlab.org>
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Begin forwarded message:

From: William Brooks <william.brooks at usm.cl<mailto:william.brooks at usm.cl>>
Subject: [EXTERNAL] Re: [Dsg-rich] RICH prototype mirror reflectivity summary
Date: 10 January 2020 at 02:08:01 CET
To: Patrizia Rossi <rossi at jlab.org<mailto:rossi at jlab.org>>

Dear Patrizia,

Thanks a million! this is a terrific measurement. Please convey my sincere appreciation to your team!!

I don’t think it is worth their time to do more measurements; since this was our first try on a carbon fiber backing including the SiO2. A value of 85% is respectable, given that it’s the first try. We will carefully analyze the data and see if we can find trends. By eye I did not see any trends, but I’d like to analyze the position dependence to see if it correlates to reflectivity, and also see if there is any wavelength dependence differences from one spot to the next.

We have information on the thickness of the SiO2 layer, although I don’t have it with me. Perhaps a thicker Al layer, or thinner SiO2 layer, would give better reflectivity.

I think I did not mention it, but the scratches seen are scratches in the mandrel, which I assume means they are actually bumps in the mirror replica.

Best regards,

 - Will


On Jan 9, 2020, at 18:59, Patrizia Rossi <rossi at jlab.org<mailto:rossi at jlab.org>> wrote:

Additional measurements.
Do you want to have some other spots to be measured?
--------------------------------------------------
# Patrizia Rossi
# Jefferson Lab
# 12000 Jefferson Avenue
# Suite 5
# Newport News VA 23606 (USA)
# e-mail: rossi at jlab.org<mailto:rossi at jlab.org>
# phone: +1 (757) 269 7740
# fax: + 1 (757) 269 5800
# cell: +1 (757) 528 7606




Begin forwarded message:

From: Tyler Lemon <tlemon at jlab.org<mailto:tlemon at jlab.org>>
Subject: [Dsg-rich] RICH prototype mirror reflectivity summary
Date: 9 January 2020 at 22:46:57 CET
To: dsg-rich <dsg-rich at jlab.org<mailto:dsg-rich at jlab.org>>

Hello,

This afternoon, we measured the reflectivity of the prototype mirror in 14 locations. A summary of the results is in the Excel file attached. I will either send or post the complete set of data tomorrow.

The test scanned wavelengths from 350nm - 650 nm in 15 nm steps, the range and steps used for the previous spherical mirrors. At each step, 25 measurements were taken. The data in the Excel file is the average of the 25 measurements.

The locations chosen to test cover some of the scratches and voids on the surface and are also in somewhat of a grid pattern with ~2 inches between spots in most places.

It seems that overall, the reflectivity is ~85% for the mirror.

If there are any spots that should be retested or any additional spots to be tested, let us know and we will do so tomorrow.

I put the mirror at my desk in EEL 121c in case it needs to be picked up by collaborators during the off hours.

Best regards,
Tyler

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<2019-01-09_prototype-mirror-refl_summary.xlsx>


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