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Re: TOF/FCAL Supporting Documents (fwd)
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/
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~