[Halld-tagger] A different magnet for the Pair Spectrometer

Wed Aug 11 10:05:42 EDT 2010

Dear Eugene,

The previous design of PS was made within electronics saving 
limitations and  without use of magnetic field variation.

  Some detector and readout simulations primary are needed to evaluate an 
impact of BL lowering to the energy resolution due to increase of 
multiple scattering and beam size influence, as well as the contribution 
of accidental coincidences.

  Some compensation of analyzing power lost  may 
be compensated by increase of  vacuum chamber length.

  As a electronics  saving approach the use of smaller area  SI,GEM 
detectors in combination with magnetic field scan may be alos 
accessible.

Best Regards, Hrachya

On Fri, 6 Aug 2010, Eugene Chudakov wrote:

> We are considering a smaller magnet for the pair spectrometer:
>  18D36 instead of 30D72. It weighs 20t instead of 65t. It can
> be split in two parts. It is a much easier magnet to handle.
>
> The gap size is 18(X)x6(Y)x36(Z) inches. The field is
> 2.0T at 2.2kA. We would shim the gap to 3", which would
> provide 2.0T at about 1.2kA.
>
> The magnet would provide a field integral up to 1.8Tm. At 1.8Tm
> the acceptance goes down to 4 GeV of the electron energy.
> The plan is to use a coordinate detector (a GEM is considered),
> at a lower field integral.
>
> The BNL has several magnets of this type and old power supplies
> for them. The same magnet is being used by PRIMEX in Hall B.
>
> Let me know if you have concerns with this change.
>
> Eugene
>
> ------------------------------------------------------
> Eugene Chudakov
> http://www.jlab.org/~gen
> phone (757) 269 6959  fax (757) 269 6331
> Thomas Jefferson National Accelerator Facility
> 12000 Jefferson Ave,
> Newport News, VA 23606 USA
>
> ---------- Forwarded message ----------
> Date: Thu, 5 Aug 2010 21:36:16 -0400 (EDT)
> From: Eugene Chudakov <gen at jlab.org>
> To: "Pendzick, Alexander F" <pendzick at bnl.gov>
> Cc: Alexander Somov <somov at jlab.org>, Liping Gan <ganl at uncw.edu>,
>     "Pile, Philip H" <pile at bnl.gov>, Timothy Whitlatch <whitey at jlab.org>
> Subject: RE: Magnet 30D72
>
> Al,
>
> thanks for the information.
>
> we are seriously considering taking this magnet (18D36) instead of
> the big one we initially planned (30D72). We need one magnet.
> We are also considering borrowing a power supply. What is
> the status of these magnets? Do we need to test it or you have some
> which have been tested recently? Have you by chance a magnet with shimmed poles
> (to about 3")?
>
> Thanks again,
> Eugene
>
> On Thu, 5 Aug 2010, Pendzick, Alexander F wrote:
>
>> Eugene
>>
>> 	 An 18D36 Mk II weighs 20 tons and can be split in half. It will
>> reach 2.2T at 3000a, with a 6" gap --2T at ~2230a. It is approximately
>> linear up to 1900a.
>> 	We have field maps, etc.
>> 	We have power supplies available but they are old.
>>
>> 	Liping borrowed one of these magnets --she should have data
>> also.
>>
>>
>> Al
>>
>>
>> -----Original Message-----
>> From: Eugene Chudakov [mailto:gen at jlab.org]
>> Sent: Wednesday, August 04, 2010 3:40 PM
>> To: Pendzick, Alexander F
>> Cc: Alexander Somov
>> Subject: RE: Magnet 30D72
>>
>> Al,
>>
>> thanks, it is a good news.
>> Have you some documentation/information on this magnet?
>> We found something but are not sure it describes the magnets
>> you have.
>>
>> a) Is it in one 20 t piece? Can it be split in two for transportation
>>    and poles' work (we would reduce the gap to about 3 inches)?
>>
>> b) What current is needed with the normal configuration to provide
>>    2 T at the center?
>>
>> c) Is there a magnitization curve? What is the linear region?
>>
>> d) Is there a field map measured?
>>
>> d) Have you also an excess power supply to use with this magnet?
>>
>> Thanks again for your help,
>>
>> Eugene
>>
>>
>> On Wed, 4 Aug 2010, Pendzick, Alexander F wrote:
>>
>>> Eugene
>>>
>>> 	We have many 18D36's and they are in good shape  ---
>>>
>>>
>>> Al
>>>
>>>
>>> -----Original Message-----
>>> From: Eugene Chudakov [mailto:gen at jlab.org]
>>> Sent: Wednesday, August 04, 2010 12:23 PM
>>> To: Pendzick, Alexander F
>>> Cc: Liping Gan; Pile, Philip H; Alexander Somov
>>> Subject: RE: Magnet 30D72
>>>
>>> Al,
>>>
>>> thank you very much for your help.
>>> We still hope to find a smaller magnet than one we originally
>>> planned to use. We found another two candidates in the same list:
>>>
>>> 18D36 and 18D40
>>>
>>> Is any of these magnets available?
>>>
>>> Thank you,
>>> Eugene
>>>
>>> ------------------------------------------------------
>>> Eugene Chudakov
>>> http://www.jlab.org/~gen
>>> phone (757) 269 6959  fax (757) 269 6331
>>> Thomas Jefferson National Accelerator Facility
>>> 12000 Jefferson Ave,
>>> Newport News, VA 23606 USA
>>>
>>> On Tue, 3 Aug 2010, Pendzick, Alexander F wrote:
>>>
>>>> Eugene
>>>>
>>>> 	We have not been able to find that magnet ----I believe we got
>>>> rid of it a few years ago.
>>>>
>>>>
>>>> Al
>>>>
>>>>
>>>> -----Original Message-----
>>>> From: Eugene Chudakov [mailto:gen at jlab.org]
>>>> Sent: Friday, July 23, 2010 7:08 PM
>>>> To: Pendzick, Alexander F
>>>> Cc: Liping Gan; Pile, Philip H; Alexander Somov
>>>> Subject: RE: Magnet 30D72
>>>>
>>>> Dear Al,
>>>>
>>>> do you have by chance another excess magnet: 20D47 ?
>>>> We found its parameters on a WWW page and realized it would also
>>>> fit our requirements and should be much easier to handle.
>>>>
>>>> Thanks,
>>>> Eugene
>>>>
>>>> ------------------------------------------------------
>>>> Eugene Chudakov
>>>> http://www.jlab.org/~gen
>>>> phone (757) 269 6959  fax (757) 269 6331
>>>> Thomas Jefferson National Accelerator Facility
>>>> 12000 Jefferson Ave,
>>>> Newport News, VA 23606 USA
>>>>
>>>> On Thu, 10 Jun 2010, Pendzick, Alexander F wrote:
>>>>
>>>>> Eugene
>>>>>
>>>>> 	A few issues associated with your proposed tests:
>>>>>
>>>>> 	These magnets weigh more than our crane capacity, therefore they
>>>>> are presently split and will have to be assembled.
>>>>>
>>>>> 	The only water we have available in the building they are in is
>>>>> domestic water ---- ~ 15 GPM @50 psi
>>>>>
>>>>> 	To look for turn to turn shorts, we normally pulse the coils out
>>>>> of the cores --- are you interested in doing this?
>>>>>
>>>>> 	Will you be bringing a DC power supply?
>>>>>
>>>>> 	While we generally recognize your training --- your test plan
>>>>> may include exposed bus tests  -- this will be a problem.
>>>>>
>>>>> 	Late summer is best for us, I believe there is interest in one
>>>>> of our spectrometer magnets--a 48D48 --- You may want to combine
>>> these
>>>>> visits.
>>>>>
>>>>>
>>>>> Al
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> -----Original Message-----
>>>>> From: Eugene Chudakov [mailto:gen at jlab.org]
>>>>> Sent: Wednesday, June 09, 2010 5:20 PM
>>>>> To: Pendzick, Alexander F
>>>>> Cc: Pile, Philip H; Timothy Whitlatch; Liping Gan; Alexander Somov
>>>>> Subject: Magnet 30D72
>>>>>
>>>>> Dear Alexander,
>>>>>
>>>>> there is an agreement to transfer a excess magnet 30D72 from the BNL
>>>> to
>>>>> the Jefferson Lab. I just talked to Phil Pile on this matter and
>>>>> he suggested to coordinate the details with you.
>>>>>
>>>>> We are planning to test several things before shipping the magnet,
>>>>> namely:
>>>>>
>>>>> (1) Insulation check,
>>>>> (2) Water leakage,
>>>>> (3) Hipot,
>>>>> (4) Coil test at a low current.
>>>>>
>>>>> Please let me know what would be the best time to fit
>>>>> this work into you schedule. Our preference is to get ready for
>>>>> shipment by the end of this summer.
>>>>>
>>>>>> From our side this activity will be coordinated by
>>>>> Liping Gan  <ganl at uncw.edu>.
>>>>>
>>>>> Thank you,
>>>>>
>>>>> Eugene
>>>>>
>>>>>
>>>>>
>>>>> ------------------------------------------------------
>>>>> Eugene Chudakov
>>>>> http://www.jlab.org/~gen
>>>>> phone (757) 269 6959  fax (757) 269 6331
>>>>> Thomas Jefferson National Accelerator Facility
>>>>> 12000 Jefferson Ave,
>>>>> Newport News, VA 23606 USA
>>>>>
>>>>
>>>
>>
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