[Halld-tracking-hw] CDC Straw Tubes

[Curtis A. Meyer]

Hi Everyone -

   I also do not like the scratches near the bottom of each ribbon, but 
I should also
point out that Tim's pictures appear worse than the true situation 
because of diffraction.
It is hard to see the scratching in the recent lamina unless you hold it 
to a light, and
we initially missed the (obvious) scratching in the kapton stone tubes, 
although it
is very visible. Most of the surface is really AL, while the pictures 
imply that it is
not.

   I also concur that they should improve the quality of the surface, 
but to be fair,
it is not as bad as the pictures make it out to be.

   curtis

On 5/18/10 6:48 PM, Eugene Chudakov wrote:
> I agree with Fernando and Elton.
>
> The new Lamina straws are not acceptable. We should discuss it with 
> Lamina. This transparency test is simple - they should be able to do 
> it themselves.
> I hope they will be able to reproduce the quality of their first batch 
> delivered a few months ago.
>
> Eugene
>
> On Tue, 18 May 2010, Tim Whitlatch wrote:
>
>> I am not referring to the gaps between tape windings, I am talking 
>> about the lines (prominent on the kapton and somewhat on the new 
>> Lamina) that run parallel to the gap
>>
>> Tim
>>
>> Curtis A. Meyer wrote:
>>> 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/