Lab upgrade

Pictures du jour here.
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This is a good place to put pix of your lab or shop intended to produce the drool reaction. If topics get lengthy here, we may want to move most of the discussion to where it fits in the org scheme here (such as it is). Good place for announcements of things you just got working and so on. Respecting readers who may not have large bandwidth, try and keep the pictures to about one megapixel -- we have the BW and the storage here, no problems, but some readers may not.

Re: Lab upgrade

Postby johnf » Mon May 02, 2011 5:06 am

Okay

I did a little video last week of the system and how easy it is to operate will post soon after the corporate image police give the okay.

Today we powered up, but the electrometer that measures target current threw a wobbly--back to Keithley with a mate that suffered a breakdown after a flashover on another system ( probably due to the same hit that wrecked the 3 phase inverter supply for the motor on the motor alternator setup.
Changed out the gas ion source for a sputter ion source with silicon targets installed ( more terminal power required for this)

more soon
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Re: Lab upgrade

Postby johnf » Tue Jan 10, 2012 12:45 pm

Okay the lab upgrade continues with an RBS spectrometer now being added behind the target chamber on the vertical implanter.
RBS uses helium nuclei (alphas) to probe the surface layers of a sample with the bounced off alphas energy proportional to Z of the sample material. More reading on this to be found on the web.
The detector for this I am about to construct out of a 4" x 2" MCP plate that will attach to the large CF blank flange directly above the ion pump. I still have to make the resistive anode for the MCP to work against that provides position information.
So far we just got the system assembled and under vacuum a couple of days before the xmas break.

IMG_0138.JPG


and a pic of the vacuum electronics showing the pressures in the sample chamber and the detector chamber

IMG_0140.JPG
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Re: Lab upgrade

Postby Jerry » Wed Jan 11, 2012 3:41 am

A 4"x2" microchannel plate? That can't be cheap...
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Re: Lab upgrade

Postby johnf » Wed Jan 11, 2012 2:50 pm

Jerry
No the price wasn't too bad
US$5500 ea I got two in case I damaged one
Active area 66 x 88 mm 10um channel diameter
Grey Hawk optics are the supplier
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Re: Lab upgrade

Postby johnf » Wed Jan 25, 2012 5:08 pm

Okay a few pics of the RBS detector MCP and the resistive anode I'm starting to make
First pic the MCP itself interesting interference pattern from all the holes in the 10um grid


second pic the fancy box they came in.

third pic the centre out of the sio2 on Si wafer that I'll build the resistive anode on ( the bit i'm using is missing --in the sputter chamber getting gold contacts
MCP.jpg


mcp2.jpg


mcp3.jpg
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Re: Lab upgrade

Postby Doug Coulter » Wed Jan 25, 2012 7:27 pm

I'm not sure I understand what you're doing here. So you bounce alphas off something and want to know the energy post-bounce, but also the position (or bounce angle)? And you're somehow going to get both off the MCP with a single readout from a resistive anode? I'm confused.
Posting as just me, not as the forum owner. Everything I say is "in my opinion" and YMMV -- which should go for everyone without saying.
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Re: Lab upgrade

Postby johnf » Thu Jan 26, 2012 3:11 am

Doug
You nearly have it
yes the alphas bounce off
first consider the bounce @ the surface a light atom will give the bounced alpha a lower energy kick than a heavier atom ie golf ball to golf ball or golf ball to bowling ball.
Now if you put the sample at an angle to the beam of impinging alphas the bounce angle becomes element weight dependant
if the alpha now goes below the surface it will loose energy going in and coming out so the corresponding energy is less and is spread towards the next lighter element --so now if you have a position sensitive detector you have abundance and depth information at the same time with out having to section the sample
very useful for light element concentrations near the surface (I dont know of any other non destructive technique)
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Re: Lab upgrade

Postby johnf » Thu Feb 02, 2012 6:57 pm

Lookie here
Father Christmas (AKA EPay) just delivered a 125kV supply
Control box arrives this afternoon

HVPSU.jpg
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Re: Lab upgrade

Postby Doug Coulter » Sun Feb 05, 2012 10:36 pm

This rates at least a yum, and perhaps a YAHOO! What's the polarity and current? I see they only used a coupla corona rings to keep arcs down, but one question I've got for these (since I have a similar disk stack to put together) is how then do you move the power to your application? I can get wire good enough, have some X ray stuff, fat shielded coax - but do you just trim back the ground shield on the power HV coax about a foot to connect to the top of this, or what? Do we put the whole shebang in a cage to keep emi and hazards down? I'd like to fire mine up at some point, but I'm wondering if the first go shouldn't be outdoors away from all the computers and so on.
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Re: Lab upgrade

Postby johnf » Mon Feb 06, 2012 12:30 am

Doug
here's the kicker on this one---its reversible just turn the stack over to change polarity
125kV max @ 1.5 mA will add a pic of the driver soon
I'll be looking at the current limit as the drive electronics has 6 TO3 devices on a heatsink-- I think I should be able to double that figure which will suit us fine.

The cable is a problem but I do have a 100m reel of 60kV neon sign transformer wire here @ home so some extra dressing should get it to 125kV--- OK will post pics when I do it
otherwise pvc pipe (3") with spacers will be the next try
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