[Halld-tracking-hw] CDC endplates, feedthrus etc (fwd)

Tue Aug 4 11:50:53 EDT 2009

Hi Eugene,

Thanks. We will proceed with the braid shield removal from the FDC 
signal cables.

Best regards,
Fernando

Eugene Chudakov wrote:
> From this I calculated that these shields from 3 FDC packages
> will make 3.5%RL. At 15 deg it will become 14%.
>
> The contribution seems to be substantial. I suggest to remove the 
> shields.
>
> Eugene
>
> ------------------------------------------------------
> Eugene Chudakov
> http://www.jlab.org/~gen
> phone (757) 269 5352 fax (757) 269 5703
> Thomas Jefferson National Accelerator Facility
> 12000 Jefferson Ave, Suite #4
> Newport News, VA 23606 USA
>
> On Tue, 4 Aug 2009, Fernando J. Barbosa wrote:
>
>> Hi Eugene,
>>
>> Eugene Chudakov wrote:
>>> Fernando,
>>>
>>> A couple of questions:
>>> - how many of such cables come from one FDC station (all 6 planes)?
>> There are 132 cables per FDC package (all 6 planes).
>>> - what is the diameter of the shield (is it round?)?
>> The cable is not truly round but oblong in profile with the outer 
>> diameter ranging from 0.295" to 0.335". The PVC jacket is 0.030" 
>> thick and the braid shield is about 0.010". Therefore, the diameter 
>> of the shield ranges from 0.225" to 0.265" (oblong, 0.245" average).
>>
>> Best regards,
>> Fernando
>>
>>
>>
>>>
>>> Thanks,
>>> Eugene
>>>
>>>
>>> ------------------------------------------------------
>>> Eugene Chudakov
>>> http://www.jlab.org/~gen
>>> phone (757) 269 6959, 5352 fax (757) 269 5703
>>> Thomas Jefferson National Accelerator Facility
>>> 12000 Jefferson Ave, Suite #4
>>> Newport News, VA 23606 USA
>>>
>>> On Sat, 1 Aug 2009, Fernando J. Barbosa wrote:
>>>
>>>> Hi Eugene,
>>>>
>>>> While we are on the subject, we need to decide if we want to remove 
>>>> the shield braid from the FDC signal cables.
>>>>
>>>> It has been our intention to remove the shield braid (~0.010" Cu 
>>>> thickness) from the FDC signal cables inside the magnet. The cable 
>>>> inside the magnet is still shielded by an Al foil (which is part of 
>>>> the cable, the cable has the Cu braid over the Al foil) and will 
>>>> then be protected by a PVC sleeve. The cost of the cable assemblies 
>>>> will be lower if we don't need to remove the braid.
>>>>
>>>> I suggest running some simulations soon as we are about to make 
>>>> some cables for the FDC prototype and this would be a good time to 
>>>> finalize the cable specs.
>>>>
>>>> Best regards,
>>>> Fernando
>>>>
>>>>
>>>>
>>>> Eugene Chudakov wrote:
>>>>> Tim suggests to use 6mm aluminum instead of 6mm carbon fiber
>>>>> composite material for the downstream endplate of the CDC.
>>>>> We made an estimate of the thicknesses involved:
>>>>>
>>>>> a) The inserts (donuts, feedthroughs, pins etc.): 3.6% RL
>>>>> b) The composite endplate (the holes make about 30% of the 
>>>>> surface): 1.9%
>>>>> b) The Al endplate with holes: 4.7%
>>>>>
>>>>> Changing the plate to Al will add 2.8% of RL,
>>>>> which is an additional loss of 11% of events with 4-photons 
>>>>> passing the plate,
>>>>> and a 20% increase of the scattering angle of charged particles in 
>>>>> the plate.
>>>>> It does not sound dramatic, unless there are many similar compromises
>>>>> in storage.
>>>>>
>>>>> ------------------------------------------------------
>>>>> Eugene Chudakov
>>>>> http://www.jlab.org/~gen
>>>>> phone (757) 269 5352 fax (757) 269 5703
>>>>> Thomas Jefferson National Accelerator Facility
>>>>> 12000 Jefferson Ave, Suite #4
>>>>> Newport News, VA 23606 USA
>>>>>
>>>>> ---------- Forwarded message ----------
>>>>> Date: Fri, 31 Jul 2009 11:24:12 -0400
>>>>> From: Tim Whitlatch <whitey at jlab.org>
>>>>> To: Curtis A. Meyer <cmeyer at ernest.phys.cmu.edu>
>>>>> Cc: Beni Zihlmann <zihlmann at jlab.org>, Eugene Chudakov 
>>>>> <gen at jlab.org>,
>>>>> Vladislav Razmyslovich <vgr at jlab.org>, Gary Wilkin 
>>>>> <wilkin at andrew.cmu.edu>
>>>>> Subject: CDC endplates, feedthrus etc
>>>>>
>>>>> Hi Curtis,
>>>>>
>>>>> After working with several vendors on the manufacturing of these 
>>>>> parts, I offer the following information and suggestions;
>>>>>
>>>>> 1. Endplate stereo angles position tolerances should be opened up. 
>>>>> The stereo holes .positional tolerance between 005 and .010 in. 
>>>>> may be possible. A change in temperature between machining and 
>>>>> measuring of 4�F will cause a change of .0025 in. on the outermost 
>>>>> holes.
>>>>>
>>>>> Recommendation: Stereo hole positions be opened up to .007, 
>>>>> straight holes to .005. The positions of the crimp pins can be 
>>>>> determined as installed by photogrammetry or CMM. (within .002)
>>>>>
>>>>> 2. Downstream endplate of carbon/epoxy composite will need to be 
>>>>> custom made. The thickness tolerance will be � .009 inches (� .005 
>>>>> for alum. plate). The plate is .236 inches thick. If we make it 
>>>>> thicker and machine it, there is a chance for warpage. The cost is 
>>>>> about $15K additional for the composite and the results are 
>>>>> questionable.
>>>>>
>>>>> Recommendation: Make downstream plate out of .25 in.aluminum. The 
>>>>> density of the carbon epoxy is about 60% of aluminum. The 3600 
>>>>> holes in the endplate remove about 1/2 of the material. The 
>>>>> feedthrus donuts and inserts dominate the mass in the area..
>>>>>
>>>>> 3. The plastic feedthrus can be injection molded for about half 
>>>>> the price of the machined parts ($113K in savings). They can be 
>>>>> injection molded if the diametral tolerances are opened to .002 to 
>>>>> .003 inches. The aluminum parts would also be cheaper with looser 
>>>>> tolerances (.001 in).
>>>>>
>>>>> Recommendation: Open up tolerance on components as stated above.
>>>>>
>>>>> Slava has updated the drawings showing many of these options. 
>>>>> please see them at:
>>>>>
>>>>> http://www.jlab.org/~vgr/CDC%20Updated%20Drawings-7-30-2009/
>>>>>
>>>>> Please consider these changes and let me know what you think.
>>>>>
>>>>> Thanks,
>>>>>
>>>>> Tim
>>>>>
>>>>> ------------------------------------------------------------------------ 
>>>>>
>>>>> _______________________________________________
>>>>> Halld-tracking-hw mailing list
>>>>> Halld-tracking-hw at jlab.org
>>>>> https://mailman.jlab.org/mailman/listinfo/halld-tracking-hw
>>>>
>>
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