sPHENIX discussion of the superconducting solenoid

[Kin Yip <kinyip AT bnl.gov>]

Hi,

I've put Carl Schultheiss' presentation related to the strain gage DAQ system (under "Past Presentation") :
https://collab.external.bnl.gov/sites/sPHENIX-Magnet/Past%20Presentations/2016-6-9%20Strain%20Gage%20DAQ%20system.pptx

As Carl has predicted, there was no real controversy.  We now wait for Winston Pekrul to tell us whether he prefers LAN/GPIB and we
can make up the PO etc.

Carl's "required resolution" page (ie. 1st page) mentions about inches (distance) ... But tust to write for myself, maybe a bit simpler
(after I what Piyush/Carl/Zeynep have educated me) version is something like this:

What we have measured (during the low-field test) were usually no. 350.xxx ohm  and the reference resistances are  around 350.yyy ohm.

From the data that we've measured, the bigger examples of delta-resistance ( 350.xxx - 350.yyy) may be 0.26 Ohm,
the smallest may be like 0.012 Ohm.   With 1 mA constant current source, these are 0.26 mV (260 uV)  and 0.012 mV (12uV).  

For a 22-bit instrument, you usually get ~20 bits (due to noise etc.).

For an input range of 1 V and 20-bit, 1 V/2^20 ~ 9.53E-7 V ~ 1uV.    Here, we use 1 uV (1 micro volt) to measure the smallest
differences like 12 uV, which is (barely) enough.   So, we really need 22-bit instrument .... not 16-bit instrument.

This is to convince myself that we really need 22-bit.

Kin