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Re: TOF/FCAL Supporting Documents (fwd)
Hall D PID Mail List:
Elke wrote:
>>http://www.magnetic-shield.com/
Yes, this site provides a calculator for simple cylindrical shields.
A 1mm mu-metal 15cm diameter would shield 20 Gs. Photonis claims
that their shilds work up to 50Gs.
In the foreseen PMT location of the gas Cherenkov detector the field is
about 150 Gs. It is obvious that a multilayer soft iron/mu-metal shield
is needed. One should be careful with calculations, since there
is a strong field gradient in this area.
Eugene
>Hall D PID Mail List:
>
>Elke is correct.
>The idea is to shield with soft iron + mu-metal.
>
>At 10:41 AM -0400 4/16/07, Elke-Caroline Aschenauer wrote:
>>Hall D PID Mail List:
>>
>>On Mon, 16 Apr 2007, Tim Whitlatch wrote:
>>
>>as usual things work at JLAB different than at DESY.
>>I absolutely don't believe that you can shield 160gauss with 1mm mu-metal.
>>I'm afraid, I would liek to see a measurment of the field in a tube of
>>1mm mu-metal.
>>
>>here is the promiosed www-page on the new metals to
>>shield fields
>>http://www.magnetic-shield.com/
>>
>>
>>elke
>>
>>> Date: Mon, 16 Apr 2007 09:27:16 -0400
>>> From: Tim Whitlatch <whitey@jlab.org>
>>> To: Elton Smith <elton@jlab.org>
>>> Cc: halld-pid@jlab.org
>>> Subject: Re: TOF/FCAL Supporting Documents (fwd)
>>>
>>>
>>> A very rough calculation shows that a 1 mm thick mu metal (80% nickel) 2
>>> inches in diameter will saturate at approx. 160 gauss (transverse DC
>>> field). The Attenuation will be about 280. I believe it will depend on
>>> the required attenuation to determine if the mu metal will work (what is
>>> the threshold sensitivity of the PMT's to the magnetic field?).
>>>
>>> Tim
>>>
>>> Elton Smith wrote:
>>> > Hall D PID Mail List:
>>> >
>>> >
>>> > HI all,
>>> >
>>> > I realized we should probably post these comments to halld-pid in case
>>> > there is other input.
>>> >
>>> > Cheers, Elton.
>>> >
>>> > Elton Smith
>>> > Jefferson Lab MS 12H5
>>> > 12000 Jefferson Ave
>>> > Suite # 16
>>> > Newport News, VA 23606
>>> > elton@jlab.org
>>> > (757) 269-7625
>>> >
>>> > ---------- Forwarded message ----------
>>> > Date: Mon, 16 Apr 2007 04:34:01 -0400 (EDT)
>>> > From: Elton Smith <elton@jlab.org>
>>> > To: Elke-Caroline Aschenauer <elke@jlab.org>
>>> > Cc: Matthew Shepherd <mashephe@indiana.edu>, Tim Whitlatch
>>><whitey@jlab.org>,
>>> > Chuck Hutton <huttonc@jlab.org>, Elton Smith <elton@jlab.org>,
>>> > Alex Dzierba <dzierba@indiana.edu>
>>> > Subject: Re: TOF/FCAL Supporting Documents
>>> >
>>> >
>>> > Hi Elke and Matt,
>>> >
>>> > We use mu-metal shields in CLAS to shield 30 G with no trouble. I can dig
>>> > up the clas notes on the subject. Going beyond that, you need multiple
>>> > layers and/or soft iron/mu-metal combinations.
>>> >
>>> > Cheers, Elton.
>>> >
>>> >
>>> >
>>> >
>>> > Elton Smith
>>> > Jefferson Lab MS 12H5
>>> > 12000 Jefferson Ave
>>> > Suite # 16
>>> > Newport News, VA 23606
>>> > elton@jlab.org
>>> > (757) 269-7625
>>> >
>>> > On Fri, 13 Apr 2007, Elke-Caroline Aschenauer wrote:
>>> >
>>> >
>>> >> On Fri, 13 Apr 2007, Matthew Shepherd wrote:
>>> >>
>>> >> Hi hi,
>>> >>
>>> >> okay very quick becaue I'm on the run to the airport. I will look to the
>>> >> nim paper to see some of it.
>>> >> But I'm very sure that with normal mu metal you can shield max
>>>some gauss.
>>> >> of course you can put really several layers around it than from layer to
>>> >> layer it gets less saturated, but in generell and we have done this more
>>> >> than ones for our tubes in hermes you use a soft steal shielding with a
>>> >> mu-metal layer inside.
>>> >>
>>> >> There is some more modern metal to shield tubes, which I have to find the
>>> >> name again, which is advertised for medium fields.
>>> >>
>>> >> Cheers and have a nice weekend
>>> >> elke
>>> >>
>>> >>
>>> >>
>>> >>> Date: Fri, 13 Apr 2007 17:16:45 -0400
>>> >>> From: Matthew Shepherd <mashephe@indiana.edu>
>>> >>> To: Elke-Caroline Aschenauer <elke@jlab.org>
>>> >>> Cc: Elton Smith <elton@jlab.org>, Tim Whitlatch <whitey@jlab.org>,
>>> >>> Chuck Hutton <huttonc@jlab.org>, Alex Dzierba <dzierba@indiana.edu>
>>> >>> Subject: Re: TOF/FCAL Supporting Documents
>>> >>>
>>> >>>
>>> >>> Hi Elke,
>>> >>>
>>> >>> You can find a NIM article on shielding studies done at IU several
>>> >>> years ago for the TOF and FCAL. (NIM A 533, 467) I didn't realize
>>> >>> that mu metal saturated at *that* low of a field. As far as I know
>>> >>> preliminary field studies show of order 100 gauss down around the
>>> >>> lead glass. If what you say is correct soft iron will be a
>>> >>> necessity. You can also find info in this paper about field strength
>> > >>> inside the tube as a function of distance from the tube. We would
>>> >>> plan this into the design -- it is also exactly what motivates the
>>> >>> use of light guides in the FCAL.
>>> >>>
>>> >>> -Matt
>>> >>>
>>> >>>
>>> >>> On Apr 13, 2007, at 8:22 AM, Elke-Caroline Aschenauer wrote:
>>> >>>
>>> >>>
>>> >>>> On Fri, 13 Apr 2007, Matthew Shepherd wrote:
>>> >>>>
>>> >>>> Do we know what the field is because if it is bigger than 2-4 gauss
>>> >>>> mu-metal will not do the trick. Please if shields are desiged
>>> >>>> account for the fact that to have them really nicely working you
>>> >>>> need to
>>> >>>> have the shieled extentding by the tube diameter from the tube
>>> >>>> surface.
>>> >>>>
>>> >>>> bye elke
>>> >>>>
>>> >>>>
>>> >>>>
>>> >>>>> Date: Fri, 13 Apr 2007 08:18:23 -0400
>>> >>>>> From: Matthew Shepherd <mashephe@indiana.edu>
>>> >>>>> To: Elton Smith <elton@jlab.org>
>>> >>>>> Cc: Elke Aschenauer <elke@jlab.org>, Tim Whitlatch <whitey@jlab.org>,
>>> >>>>> Chuck Hutton <huttonc@jlab.org>, Alex Dzierba
>>> >>>>> <dzierba@indiana.edu>
>>> >>>>> Subject: Re: TOF/FCAL Supporting Documents
>>> >>>>>
>>> >>>>>
>>> >>>>> Hi Elton,
>>> >>>>>
>>> >>>>> I don't know off the top of my head whether or not mu-metal will be
>>> >>>>> enough for the ToF. Maybe Alex can comment more since he is more
>>> >>>>> familiar with the ToF design. As far as I know magnetic field tests
>>> >>>>> were done here at IU using mu metal and soft iron together -- none
>>> >>>>> were done with mu metal alone. I would assume this means there was
>>> >>>>> an expectation to use soft iron.
>>> >>>>>
>>> >>>>> To help with interference between tubes, the tubes could be placed at
>>> >>>>> an angle alternating back and forth every other bar. The soft iron
>>> >>>>> and mu metal would not have to go down to the scintillator -- it
>>> >>>>> would just need to protect the PMT area.
>>> >>>>>
>>> >>>>> Again, I understand your need and urgency for an actual mechanical
>>> >>>>> drawing to vet this design and explore potential interferences. For
>>> >>>>> the last 6 months we have had no one at IU capable of doing any
>>> >>>>> drawing or mechanical design. We are currently advertising and hope
>>> >>>>> to hire someone soon.
>>> >>>>>
>>> >>>>> -Matt
>>> >>>>>
>>> >>>>>
>>> >>>>> On Apr 13, 2007, at 7:33 AM, Elton Smith wrote:
>>> >>>>>
>>> >>>>>
>>> >>>>>> HI Matt,
>>> >>>>>>
>>> >>>>>> Thanks for the documentation. We are trying to get top-level
>>> >>>>>> drawings for
>>> >>>>>> all the subsystems and in particular we want to have a more
>>> >>>>>> realistic
>>> >>>>>> sketch of the light guide/pmt assembly for the tof. Are the any
>>> >>>>>> space
>>> >>>>>> conflicts with stacking the pmt with mu-metal shields? We were
>>> >>>>>> concerned
>>> >>>>>> because we thought that soft iron shields might be necessary.
>>> >>>>>>
>>> >>>>>> Thanks, Elton.
>>> >>>>>>
>>> >>>>>> Elton Smith
>>> >>>>>> Jefferson Lab MS 12H5
>>> >>>>>> 12000 Jefferson Ave
>>> >>>>>> Suite # 16
>>> >>>>>> Newport News, VA 23606
>>> >>>>>> elton@jlab.org
>>> >>>>>> (757) 269-7625
>>> >>>>>>
>>> >>>>>> On Fri, 13 Apr 2007, Matthew Shepherd wrote:
>>> >>>>>>
>>> >>>>>>
>>> >>>>>>> Hi Elke and Elton,
>>> >>>>>>>
>>> >>>>>>> Attached please find some supporting documents for TOF and FCAL
>>> >>>>>>> budget items.
>>> >>>>>>>
>>> >>>>>>> FCAL:
>>> >>>>>>>
>>> >>>>>>> - quote for fabrication of the PCB's for the CW bases
>>> >>>>>>> - quote for assembly of *electrical* portion of CW base
>>> >>>>>>> - quote for sheets of Sylgard for optical coupling of light
>>> >>>>>>> guides to
>>> >>>>>>> PMT
>>> >>>>>>>
>>> >>>>>>> On the last item: this quote is mainly proof of principle that
>>> >>>>>>> we can
>>> >>>>>>> get costs down to ~$1 per cookie. (In small quantities we paid $20
>>> >>>>>>> each so there was great concern as to whether or not using a
>>> >>>>>>> commercially manufactured cookie was even possible.) It gets
>>> >>>>>>> lumped
>>> >>>>>>> in with light guide costs in the budget. Sergey has estimated $20K
>>> >>>>>>> total to produce aluminized light pipes.
>>> >>>>>>>
>>> >>>>>>> TOF:
>>> >>>>>>>
>>> >>>>>>> - quote for XP2020 tubes, bases and mu metal shields
>>> >>>>>>> - quote for scintillator
>>> >>>>>>> - quote for cables
>>> >>>>>>>
>>> >>>>>>> -Matt
>>> >>>>>>>
>> > >>>>>>>
>>> >>>>>>>
>>> >>>>>>>
>>> >>>>>
>>> >>>> ( `,_' )+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=
>>> >>>> ) `\ -
>>> >>>> / '. | +
>>> >>>> | `, Elke-Caroline Aschenauer =
>>> >>>> \,_ `-/ -
>>> >>>> ,&&&&&V Jefferson Lab +
>>> >>>> ,&&&&&&&&: HALL-D 12C / F381 121-A Atlantic Avenue =
>>> >>>> ,&&&&&&&&&&; Mailstop: 12H5 Hampton, VA 23664 -
>>> >>>> | |&&&&&&&;\ 12000 Jefferson Ave +
>>> >>>> | | :_) _ Newport News, VA 23606 Tel.: 001-757-224-1216 =
>>> >>>> | | ;--' | Mail: elke@jlab.org Mobil: 001-757-256-5224 -
>>> >>>> '--' `-.--. | +
>>> >>>> \_ | |---' Tel.:
>>> >>>> 001-757-269-5352 =
>>> >>>> `-._\__/ Fax.:
>>> >>>> 001-757-269-6248 -
>>> >>>> +=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-
>>> >>>> +=-+=-+
>>> >>>>
>>> >>>>
>>> >>>
>>> >> ( `,_' )+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=
>>> >> ) `\ -
>>> >> / '. | +
>>> >> | `, Elke-Caroline Aschenauer =
>>> >> \,_ `-/ -
>>> >> ,&&&&&V Jefferson Lab +
>>> >> ,&&&&&&&&: HALL-D 12C / F381 121-A Atlantic Avenue =
>>> >> ,&&&&&&&&&&; Mailstop: 12H5 Hampton, VA 23664 -
>>> >> | |&&&&&&&;\ 12000 Jefferson Ave +
>>> >> | | :_) _ Newport News, VA 23606 Tel.: 001-757-224-1216 =
>>> >> | | ;--' | Mail: elke@jlab.org Mobil: 001-757-256-5224 -
>>> >> '--' `-.--. | +
>>> >> \_ | |---' Tel.: 001-757-269-5352 =
>>> >> `-._\__/ Fax.: 001-757-269-6248 -
>>> >> +=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+
>>> >>
>>> >>
>>> >>
>>> >
>>> >
>>>
>>
>> ( `,_' )+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=
>> ) `\ -
>> / '. | +
>> | `, Elke-Caroline Aschenauer =
>> \,_ `-/ -
>> ,&&&&&V Jefferson Lab +
>> ,&&&&&&&&: HALL-D 12C / F381 121-A Atlantic Avenue =
>>,&&&&&&&&&&; Mailstop: 12H5 Hampton, VA 23664 -
>>| |&&&&&&&;\ 12000 Jefferson Ave +
>>| | :_) _ Newport News, VA 23606 Tel.: 001-757-224-1216 =
>>| | ;--' | Mail: elke@jlab.org Mobil: 001-757-256-5224 -
>>'--' `-.--. | +
>> \_ | |---' Tel.: 001-757-269-5352 =
>> `-._\__/ Fax.: 001-757-269-6248 -
>> +=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+
>
>
>--
>~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>Alex R. Dzierba
>Chancellor's Professor of Physics (Emeritus)
>Department of Physics / Indiana U / Bloomington IN 47405 / 812-855-9421
>JLab Visiting Fellow
>Jefferson Lab / 12000 Jefferson Ave / Newport News, VA 23606 / 757-269-7577
>Home Phone: 812-825-4063 Cell: 812-327-1881 Fax: 866-541-1263
>http://dustbunny.physics.indiana.edu/~dzierba/
>~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~