[Clas12_rich] Mirror 5C-Autocad3D measurements

[Amrit Yegneswaran]

hi brian, 
good job. 
thanks for double checking, i appreciate that very much. 
patrizia sent an e-mail that the lengths are critical, there is only 3mm tolerance. 
so perhaps sandro et.al could advise us and we can come up with a plan of how to survey the length dimensions to get a real precise value on the length. 
anyway, someone (i forget who ) from INFN is going to be here, so we could get together and discuss these issues. 
have a nice long weekend, to one and all. 
amrit 



From: "Brian Eng" <beng at jlab.org> 
To: "Tomassini Sandro" <sandro.tomassini at lnf.infn.it> 
Cc: "clas12 rich" <clas12_rich at jlab.org> 
Sent: Friday, July 1, 2016 5:43:53 PM 
Subject: Re: [Clas12_rich] Mirror 5C-Autocad3D measurements 

Doing a least squares fit I get pretty much the same numbers for mirror 5C as the survey group did. All the numbers are in units of mm. 

Back surface sphere radius: 2735.65632782 with RMS of 0.0891485148111 
Sphere center: 1757.05061408, -1419.56605411, -0.169281068618 

Mirror surface sphere radius: 2696.26510045 with RMS of 0.0696200623859 
Sphere center: 1746.89907226, -1410.89622076, -0.0705877320044 

It should be noted that their calculated center points are off about ~10 in X,Y which might explain getting a difference of ~35 instead of the expected 25. 

I've put the code and data file (the same as the one Jim sent) here if anyone wants to mess with it. 

https://userweb.jlab.org/~beng/RICH/ 

It isn't very elegant, but it should be fairly obvious what it is doing. 

> On Jul 1, 2016, at 3:48 PM, Tomassini Sandro <sandro.tomassini at lnf.infn.it> wrote: 
> 
> Hi Pablo 
> 
> Thanks for your analisys. As you can see the outer radius is smaller than the inner one... 
> It should happen the contrary. 
> Next time we should distribute better the measured points on the mirror surface. 
> Have a nice weekend 
> Sandro 
> 
> Dr Eng. S. Tomassini 
> 
> Il 01/lug/2016 21:13 Pablo Campero <campero at jlab.org> ha scritto: 
>> 
>> Hello Sandro, 
>> I took your suggestion and I made the calculations of the radius for the inner and outer surfaces, I took more points (21). It looks better now. The results that I got were: 
>> -Mirror Surface (Inner): <2694>±81[mm] 
>> -Back surface(Outer): <2678>±73[mm] 
>> -For both surfaces the St.DEV. is ~3% of the average. 
>> 
>> Both values cover the theoretical specs. I propose in the future, if is necessary; a program .can be written to take all combinations (32*32*21*21=451584) of the measurements. 
>> Have a nice weekend. 
>> 
>> 
>> Best Regards 
>> Pablo Campero 
>> Detector Support Group. 
> 
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