The bluest MCA - Lecroy qVt

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ChristofferBraestrup
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Joined: Sat Apr 11, 2020 9:47 am
Real name: Christoffer Braestrup

The bluest MCA - Lecroy qVt

Post by ChristofferBraestrup »

I just received this from ebay, and I'm already hooked.

A 2-unit NIM module MCA!

The Lecroy/ LRS 3001 qVt

made by lecroy in the 70s or 80s, this little module uses an oscilloscope in XY mode as display!

Seen below is Am241 spectrum obtained with a bicron 1.12x1.12m3 1.12l at 750V, fed via preamp to a shaping amp, 25x , 2us, through a 5x attenuator to the qVt.

But that's overkill! The thing has a built in charge amp, allowing direct detector interface sans preamp! Hence the "q" in qVt.
V is standard mca mode, and t is TAC mode with start/stop inputs, for time-of-flight and other experiments.

There are plenty of add on modules, rs232 interfaces, CAMAC modules, cursor and discrete value readout, and XY plotter interface.

Now I just need one of those tiny NIM oscilloscope displays..

The weird fuzz on the spectra is all but gone now, not sure what it was.

Get one if you can! It's a great little blue friend in your bin!

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ChristofferBraestrup
Posts: 131
Joined: Sat Apr 11, 2020 9:47 am
Real name: Christoffer Braestrup

Re: The bluest MCA - Lecroy qVt

Post by ChristofferBraestrup »

Just wanted to show that the fuzz disappear after a minute of warm up.. maybe some digital decoupling needs replacing?

Oh and an original advert from the CERN Courier! This thing was NOT cheap!
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Richard Hull
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Re: The bluest MCA - Lecroy qVt

Post by Richard Hull »

Sweet! A really nice setup for your bin and looks like it will serve you well. From what I was barely able to ready on the cut sheet, with my squinty old eyes, it looks like it has 1024 channels. Good luck with it in any future efforts at activation or material identification. You have a real find there!

I have a little blue friend in my Neutron NIM bin and have had it there since 2004. It's a Le Croy dual gate generator 222N. I attach an image of my bin. I love Le Croy stuff! Among my 6 digital storage scopes is a nice Le Croy 200mhz storage scope. I bought it from Carl Willis years ago. four of the adjustment knobs were snapped off! Carl had cut slots in the stubs so he could use a jewelers screw drive to adjust the functions.

I spent about 2 weeks pulling the controls. (Euro metric jobs). I machined new full-length metric shafts, re-installed the controls, then made custom machined inserts to install U.S. small shaft knobs on the repaired controls. I used The Le Croy in the upstairs lab for a year and then got a super deal at a hamfest on a 400mhz Tektronix digital storage scope that is loaded to the gills with all available modules, FFT, RS-232 - Centronics, GPIB, Floppy drive, 15pin RGB, etc. I could not fish out the $180 in cash fast enough at that hamfest to buy it. It works great! I now use this "super scope" upstairs in my lab and the poor amber screen CRT, Le Croy has joined my other 4 reserve data storage Tektronix scopes under my electronics bench.

Richard Hull
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One of my best recent Rhodium activation one minute counts.  My "blue baby" Le Croy is easily seen in my NIM rack.... Been there since 2004
One of my best recent Rhodium activation one minute counts. My "blue baby" Le Croy is easily seen in my NIM rack.... Been there since 2004
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ChristofferBraestrup
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Joined: Sat Apr 11, 2020 9:47 am
Real name: Christoffer Braestrup

Re: The bluest MCA - Lecroy qVt

Post by ChristofferBraestrup »

What a great looking setup!

Yes, the Lecroy gear is orders of magnitude nicer than the competitors in many cases! It's one of my main motivations for getting a CAMAC crate. 16 ch. Lecroy CAMAC ADC's are everywhere.

Here is the LRS3001 qVt manual: https://physics-astronomy-manuals.wwu.e ... anual.pdf for reference.

The parallel interface is pretty simple to figure out, it would be fairly easy to make a small box with an Arduino to dump the bins to a text file on the PC. I would still REALLY like to find the qVt to XY plotter module, since I have a gorgeous Brüel & Kjaer plotter in my setup already.

I'll have to try out the charge input, that would be REALLY handy for a small MCA setup.
ChristofferBraestrup
Posts: 131
Joined: Sat Apr 11, 2020 9:47 am
Real name: Christoffer Braestrup

Re: The bluest MCA - Lecroy qVt

Post by ChristofferBraestrup »

Here is a very nice spectrum of K40 taken with the detector mentioned above at 1kV fed directly into the "q" input of the qVt!

Run time approx 90 min.

I think the fuzz is an artifact of it being a vector display with no blanking- it has to show the traces between all points on the screen.

Anyway being able to directly compare detectors without pre amplification is going to be very helpful.

If only it could take direct signals from semiconductor detectors!
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