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Re: TOF/FCAL Supporting Documents (fwd)
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 -
+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+