[Tpe] Fwd: Fwd: Re: Fwd: bcms

[Larry Weinstein]

Dear Folks,

It is entirely possible that the Beam Current Monitors are badly 
calibrated at currents of 0.3 nA.  See emails below.

- Larry

-------- Original Message --------
Subject: 	Fwd: Re: Fwd: bcms
Date: 	Thu, 15 Dec 2011 17:02:38 -0500
From: 	Stepan Stepanyan <stepanya at jlab.org>
To: 	Weinstein, Lawrence B. <lweinste at odu.edu>



Dear Larry,

Here is the response from Arne. When we measure 0.3 nA, TPE had higher 
currens.

Regards, Stepan

-------- Original Message --------
Subject: 	Re: Fwd: bcms
Date: 	Thu, 15 Dec 2011 16:45:18 -0500
From: 	Arne Freyberger <freyberg at jlab.org>
To: 	Stepan Stepanyan <stepanya at jlab.org>



I suggest that a beam test be performed.    0.3nA is below the 
specifications.  The fact that they work at all for these low currents 
was kind of a surprise.  But by optimizing the lock-in amplifiers  for 
such low currents they might be useful for current measurements.     
They will have to be cross calibrated against the FCUP.   Not sure what 
range the calibration for FCUP covers, so that too might have to be 
adjusted.

Arne

On 12/15/2011 04:02 PM, Stepan Stepanyan wrote:
> Hi Arne,
>
> Do you have any idea how well BPMs measure these low currents.
>
> Thanks, Stepan
>
> -------- Original Message --------
> Subject: 	bcms
> Date: 	Thu, 15 Dec 2011 14:46:42 -0500
> From: 	Larry Weinstein <lweinste at odu.edu>
> Reply-To: 	weinstein at odu.edu
> To: 	stepan Stepanyan <stepanya at jlab.org>
>
>
>
> Dear Stepan,
>
> How precise are the beam current monitors for currents of 0.3 nA?  How
> well do they determine the integrated current?  1%, 10%, 50%?
>
> -- 
> 				Sincerely,
> 				Larry
>
> -----------------------------------------------------------
> Lawrence Weinstein
> University Professor
> Physics Department
> Old Dominion University
> Norfolk, VA 23529
> 757 683 5803
> 757 683 3038 (fax)
> weinstein at odu.edu
> http://www.lions.odu.edu/~lweinste/

-- 
Arne Freyberger
Director of Accelerator Operations
Jefferson Lab           Office: (757) 269-6268
12000 Jefferson Avenue  Cell:   (757) 876-6289
Newport News, VA 23606  Email:freyberg at jlab.org

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