[Clas12_rich] RICH task list questions

[Marco Contalbrigo]

Dear Tyler,
in my talk at the mid-term review
https://clasweb.jlab.org/wiki/index.php/2015_October_13_RICH_Project_Mid-term_Review

I showed on slide 8 and 9 the effect on aerogel of humidity exposure.
At 40% relative humidity, you get around a percent effect per hour on
the optical performance and a corresponding percent weigth increase.
The trend seems to saturate, as the aerogel tend to reach an equilibrium 
with the external environment, but we did not try to prove it as an
excess of moisture may have irreversible effects. When we put back the
aerogel in a dry environment, it recovers with a somehow slower speed.
It is not clear however if we can eventually restore the pure original
quality without a baking procedure. At CERN we worked without N2,
but it was dry winter and we did not have a spectrophotometer to
monitor the optical quality in detail.

What I fear more is any contaminant different from water. This may
require baking, or any unknown procedure to be removed.

With the russian producer, we agreeded the following:

The material must be handled with great care according to the following 
rules:
- aerogel tiles must not be stacked on top of each other
- appropriate gloves must be used for all manipulations to prevent 
formation of fingerprints
- surgical masks or similar must be used by personnel during all 
manipulations of aerogel
- do not touch the upper surface of the tiles.
The tiles must be packed in plastic envelopes or boxes and stored in a dry 
atmosphere with relative humidity not exceeding 7%.
During testing procedures, the exposure to air, at room temperature not 
exceeding 27 C and maximum humidity of 60%, must be reasonably minimized. 
The total exposure time during 24 hours must not exceed 2 hours.

About the space: as Valery mentioned, we can borrow additional space
in a large SVT dry cabinet. We can also decide a different way to
stack the tiles: or use additional shelfs or storing the tiles
in vertical position with a sort of holder. We can discuss it
in ~10 days, when we will all be at JLab.

Ciao, Marco.

On Thu, 2 Jun 2016, Valery Kubarovsky wrote:

> Dear Tyler,
> 
> Safety documentation:
>  1. Is the THA correct?
>  2. Who will be writing the Operational Safety Procedure (OSP) for the detector?
> As I wrote in my previous mail the THA is incorrect in the part of N2. 
> 
> For a moment we need to write the OPS only for the cooling system. The other subsystems have low risk factor and we
> don't need to write OPS. I think that OPS for cooling system has to be written by people who is designing it. 
>  1. Since Valery mentioned that the moisture can be heated out of the aerogel, I guess it wouldn't be an issue to store
>     the aerogel in the open cleanroom since space is running out in the dry boxes.
> We have additional dry box in the clean room. We can use it. It belongs to HallB SVT group. Aerogel has to be stored in
> the dry box all the time. 
> 
> Regards,
> Valery
> 
> 
> 
> On Jun 2, 2016, at 13:03, Tyler Lemon <tlemon at jlab.org> wrote:
>
>       Safety documentation:
>        1. Is the THA correct?
>        2. Who will be writing the Operational Safety Procedure (OSP) for the detector?
>       Aerogel delivery:
>        1. What are the delivery dates for the remaining aerogel shipments?
>        2. Since Valery mentioned that the moisture can be heated out of the aerogel, I guess it wouldn't be an
>           issue to store the aerogel in the open cleanroom since space is running out in the dry boxes.
> 
> 
>