[Halld-tracking-hw] CDC Straw Tubes

[Beni Zihlmann]

Hi All,
compared to the old Lamina tubes the new ones are really bad. I am 
concerned that these
scratches produce spikes in the aluminum surface that could be a 
potential cause for spark
discharges to the wire (lighting striking the tip of a tree).
Because these scratches run perfectly parallel to the  aluminum  tape it 
can not be caused
by the mandril it is wound on. I think it is either already there from 
the beginning and was
caused during the production of the tape or in the winding process onto 
the mandril the
tape has to pass over some rollers somehow and if these rollers or one 
of them has a damaged
surface and/or the roller does not really role anymore but is stuck such 
scratches cold
happen (my half cent input).

cheers,
Beni

> 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
>>>>>>>
>>>>>>>               
>>>>>