[Halld-tagger] PS magnet mapping requirements

Wed Feb 26 12:52:35 EST 2014

The mapper can go 40 CM outside the iron on the downstream end in it's current configuration. 

Tim Whitlatch 
Hall D Engineer 
Jefferson Lab 
12050 Jefferson Ave ste 402 
Newport News, Va 23606 
757-269-5087 

----- Original Message -----

From: "Alexander Somov" <somov at jlab.org> 
To: "Timothy Whitlatch" <whitey at jlab.org> 
Cc: halld-tagger at jlab.org, "Daniel Sober" <sober at cua.edu>, "Eugene Chudakov" <gen at jlab.org> 
Sent: Wednesday, February 26, 2014 12:47:52 PM 
Subject: Re: [Halld-tagger] PS magnet mapping requirements 

Hi All, 

The number of configurations can be reduced depending 
on the mapping results (how symmetric the field is). 
The tentative procedure could be 

1. Map the fild along the beamline for B = 1.8 T (Y = 0) 
and compare with TOSCA 

2. Make a 2-D map for various fields: B = 1.8 T, 1.9 T, 
1.5 T (1 T?) 

3. Make a 2-D map for B = 1.8 T at Y = -1 cm and 1 cm. 
We'll decide what to do next when we get data. 

How far can the mapper go outside the magnet (to the fringe 
field region) ? 

Cheers, 
Alex 

On Wed, 26 Feb 2014, Timothy Whitlatch wrote: 

> Hi All, 
> 
> Alexandre and I talked about this yesterday and it is possible to do. The precision of the Bz and Bx angles may not be perfect. Keep in mind... 
> 
> 1) With 1cm intervals in x and y, there will approximately 4500 points being taken. This equates to ~ 6hrs per run 
> 2) With the current mapper design we will not be able to map at y = 3cm. We may be able to get y=2cm with some very minor modifications. 
> 3) In order to calibrate the Hall probes for each configuration (the proposed plan shows 5) the probes would have to be reset to the By position and then back to Bz, Bx each time 
> 4) Survey and alignment will need to re-survey for each configuration 
> 
> Timeframe for proposed 4 fields and 5 configurations would optimistically be .. 
> 
> Setup/fiducialization/calibration for each config. 1 day each - 5 days total 
> Mapping each config - 5 configs x 4 fields x 1 day each - 20 days total 
> 
> This is 5 weeks if all goes very well. I would double this and assume 50 working days or 2.5 months once we start. 
> It will probably be about a week before we start mapping (optimistically), maybe 2 weeks. 
> 
> This brings us to finishing between April 15th and June 1. 
> Of course this can be sped up with multiple shifts. 
> 
> This was originally thought to be the "easy" magnet to map. 
> 
> My 2 cents..... 
> 
> 
> Tim Whitlatch 
> Hall D Engineer 
> Jefferson Lab 
> 12050 Jefferson Ave ste 402 
> Newport News, Va 23606 
> 757-269-5087 
> 
> ----- Original Message ----- 
> 
> From: "Alexander Somov" <somov at jlab.org> 
> To: "Daniel Sober" <sober at cua.edu> 
> Cc: halld-tagger at jlab.org 
> Sent: Wednesday, February 26, 2014 9:31:46 AM 
> Subject: Re: [Halld-tagger] PS magnet mapping requirements 
> 
> Hello Dan, 
> 
> Yes, the alignment may be a problem. We'll see what we can do 
> If it doesn't work, we give it up (it's not essential). 
> 
> By the way, have you used a 3D hole probe before ? 
> 
> Cheers, 
> Alex 
> 
> 
> On Wed, 26 Feb 2014, Daniel Sober wrote: 
> 
>> Alex, 
>> If you do rotate some of the probes, remember that very precise angular 
>> alignment is necessary in order that the horizontal components not be swamped 
>> by the much larger vertical field. They should be tested in the uniform 
>> field region (where they should read close to zero.) 
>> Dan 
>> 
>> On 2/26/2014 9:06 AM, Alexander Somov wrote: 
>>> Hello Richard, 
>>> 
>>> As there are 5 hole probes mounted on the mapper (1 cm apart from 
>>> each other), I think that it would make sense to rotate 2 of them to 
>>> measure Bz and Bx just for consistency check. As the mapping 
>>> area is small, I would make the step size 1 cm. 
>>> 
>>> If TOSCA agrees well for By, we'll use the whole map from TOSCA. 
>>> 
>>> Cheers, 
>>> Alex 
>>> 
>>> 
>>> 
>>> On Wed, 26 Feb 2014, Richard Jones wrote: 
>>> 
>>>> Alex, 
>>>> 
>>>> The plan looks good. You ask at the bottom of the page whether one can 
>>>> rotate two of the probes to measure Bx and By. You should be able to 
>>>> compute those from a map of Bz only, using the symmetry of the field and 
>>>> the fact that (del x B) = 0 in the region outside the coils and the iron. 
>>>> Is that what you want to check? 
>>>> 
>>>> -Richard J. 
>>>> 
>>>> 
>>>> On Tue, Feb 25, 2014 at 9:26 AM, Alexander Somov <somov at jlab.org> wrote: 
>>>> 
>>>>> Hi, 
>>>>> 
>>>>> I've started putting requirements for mapping 
>>>>> the PS magnet to 
>>>>> 
>>>>> https://halldweb1.jlab.org/wiki/index.php/Plan_for_mapping_PS_magnet 
>>>>> 
>>>>> Please take a look. 
>>>>> 
>>>>> Cheers, 
>>>>> Alex 
>>>>> 
>>>>> _______________________________________________ 
>>>>> Halld-tagger mailing list 
>>>>> Halld-tagger at jlab.org 
>>>>> https://mailman.jlab.org/mailman/listinfo/halld-tagger 
>>>>> 
>>> _______________________________________________ 
>>> Halld-tagger mailing list 
>>> Halld-tagger at jlab.org 
>>> https://mailman.jlab.org/mailman/listinfo/halld-tagger 
>> 
>> -- 
>> /Daniel Sober 
>> Professor 
>> Physics Department 
>> The Catholic University of America 
>> Washington, DC 20064 
>> Phone: (202) 319-5856, -5315 
>> E-mail: sober at cua.edu/ 
>> 
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