[Halld-tracking-hw] CDC Straw Tubes

[Curtis A. Meyer]

I believe that we were within specifications on the line (the gap 
between wraps).
It is only the scratches that worry me --  curtis


On 5/18/10 12:34 PM, Tim Whitlatch wrote:
> Thanks Curtis. This means that the transparency (lines along the tape 
> direction) is not a concern?
>
> Tim
>
> Curtis A. Meyer wrote:
>> Hi Tim -
>>
>>    as far as we know the old kapton straws have held up. We were just 
>> concerned that
>> with all the scratches, a small amount of damage to the straw could 
>> leave some section
>> of the straw floating "electrically". Optimally, we would like to 
>> achieve what Lumina
>> did with the first straw sample that they sent us. That may not be 
>> possible, but reducing the
>> amount scratches woul be very good.
>>
>>    Quantitatively, it is harder to call. I am concerned that in some 
>> of the straws, the scrathed
>> area will "float". While it is good that it is confined to about 25% 
>> of the surface area, I would
>> like to see that reduced by about a factor of two (at least).
>>
>>       -- curtis
>> On 5/18/10 11:59 AM, Tim Whitlatch wrote:
>>> I have taken pictures against a back light of the 3 straw samples 
>>> Curtis gave me. They can be found at;
>>>
>>> http://www.jlab.org/Hall-D/software/wiki/index.php/CDC#Straws
>>>
>>> I am trying to get a handle on the requirements for the straws. The 
>>> first shows the Stone aluminized Kapton with a back light. As can be 
>>> seen, most is transparent and the lines can be seen in the direction 
>>> of the wrap. The 2nd is the latest Lamina aluminized mylar. There 
>>> are some lines that are transparent and some scratches.
>>> The 3rd is the original Lamina aluminized straw from Last fall 
>>> (supposedly the same material as the new ones) This is completely 
>>> solid against the back light.
>>>
>>> What is the requirement here?
>>> Had the kapton straws held up over the past couple of years in the 
>>> prototype setup?
>>> Is the original Lamina straw acceptable?
>>> I just wish to be clear before I get with the Lamina rep on this.
>>>
>>> Thanks,
>>>
>>>       Tim
>>>
>>>
>>> Curtis A. Meyer wrote:
>>>> Hi Everyone -
>>>>
>>>>        we have finished going through the 252 straws that were sent 
>>>> to us by Lumina.
>>>> Other than the scratches that we talked about at the meeting last 
>>>> week, the straws
>>>> appear to be pretty good. The final numbers on the mechanical 
>>>> acceptance are:
>>>>
>>>>      186/252 straws are good
>>>>        28/252 straws were rejected because they were oval. Better 
>>>> packing in the
>>>>                    shipping box would probably recover all of 
>>>> these. This would give
>>>>                    us an acceptance rate of:
>>>>      214/252  or 84.9%   and we would need 4120 straws to get 3500.
>>>>
>>>>      Of the rejected ones,  19 were rejects due to imperfections in 
>>>> the straws,
>>>>      wrapping, glueing, extra crud stuck to them, ..... The 
>>>> remaining 17 were
>>>>      bowed beyond the 1/10 inch specification. This appears to be 
>>>> in the straw
>>>>      and not due to shipping or packing.
>>>>
>>>>       In order to improve the regular shipment, the box containing 
>>>> the straws probably
>>>>       needs to be compartmentalized so that there are fewer straws 
>>>> pressing on each other.
>>>>       Perhaps a wine-crate like structure that has ~ 40 straws in 
>>>> each compartment???
>>>>
>>>>       The overall biggest issue that we saw was the scratches on 
>>>> the straws. The vendor did
>>>> not have that on the original samples that we received (a year ago).
>>>>
>>>>     Curtis
>>>>
>>
>>


-- 
Prof. Curtis A. Meyer		Department of Physics
Phone:	(412) 268-2745		Carnegie Mellon University
Fax:	(412) 681-0648		Pittsburgh PA 15213-3890
cmeyer at ernest.phys.cmu.edu	http://www.curtismeyer.com/