Alpha/Beta Scalers/Ratemeters and Probes

[alphaman]

If you were to recommend a brand of the above, which one would it be and why?  I propose these questions as I have been given the project to research the above and there is no better way than to ask those that actually use them.  I use E-600's with either an SHP-380A or SHP-380AB probe.  Thanks for your input.....

[Rennhack]

Most of the instruments I use are Ludlums.  Thats what I'm given.   I do like them though.  The 2224-1 is a nice little box.  I also like the 43-89 probe for a/b.  2929 for a scaler (Or tennelec if it's available).

[Druid]

The 2224-1 with 43-89 and 2929 are good instruments, but we are using the newer Ludlum 2360 with 43-93 and 3030.

On the plus side. The 43-93 has about the same probe area but the PMT is smaller and mounted differently so you get a smaller package with a slightly improved efficeincy. The 2360 and 3030 have an RS232 for downloading data to a computer and setting alarm set points. Also the 3030 gathers it's own voltage plateau data.

Some of the down side. The 43-93 has a very open screen, great for efficiency, bad for holes in the mylar. If you use it get 3 layer mylar, you lose a few percent but save in durability. The 3030 is heavier than the 2929.

[SloGlo]

alphaman.... what are you using these for?  iffen ya got extreme field conditions, then i personally like (due primarily to experience)the ludlum 2221.  itz a bit oldfashioned, no beeps 'n whistles, but ya can throw the thing off a dirt pile while attempting to keep yer balance 'n it'll still work (actual field test results... dirt pile was 20' high, meter contacted base of pile , then rolled into the weeds).  also, you kin operate any damn probe offa the thing.  coupla tweaks of the set screws in yer in business fer alpha, beta, or gamma.... probably do neutron too, just haven't tried it yet.  can't download to a puter... damn the bad luck, gotta keep doing the pen 'n paper routine... well, time is money, right?   that's wot eye thought two.  43-68 probes are good, 'n they got different style handles available for them so's ya kin get them into low profile spaces.  using the gas proportional probes makes easy repair in the field... scintillators need just a bit more care, 'n they got that whole daylight spectrum problem thingie.  scalers are a different horse.... 2929 & 3030 are both good, just different generations.... how much moola ya got?
so's it all depends on yer work site environment, let me know sum particulars, 'k?

[alphaman]

Thanks for the replies so far.  The conditions are harsh with lots of loose contamination.  Instruments will be used for release purposes as well as for outgoing shipments.  The, as you know, shipment checks are extremely important.  I like the Ludlums although I am used to the gamma versions.  Durable and reliable....just not familiar with the alpha/beta.  We have had bad experiences with gas probes.  Scintillation probes have been good....still have to deal with punctures.  Being an old PWR rent a tech, the alpha thing is a new world in itself.  I can relate to your meter story SloGlo.  Back in 82 I lead a team of HPs into 22k gallon tank for release surveys when I knocked an E-120 off a ledge to concrete 20 ft below....not as lucky as you...more like the watermelon drops Letterman used to do.  Also, do you report your results in cpm or dpm?  If dpm, what do use for an efficiency?  or is it determined during calibration?

[Mike_Koehler]

I've used the E-600/SHP-380A or AB  and discovered that the promise of using 1 instrument in relatively high contamination areas (>100K to  > 6 million dpm beta-gamma) is a farce due to cross-talk between channels.  We are currently using instruments that are older than I am so I don't know of anything that is substantially better unless you are in a "pristine environment " like a lab.


Good Luck

[SloGlo]

alphaman... re: reporting of contamination; i am comfortable using either dpm or cpm, doesn't make a whole lot of difference.  personal professional preference is to report in cpm.  that way, anyone downstream can do the conversions to their hearts content, as long as the reports and/or surveys list the corresponding efficiencies, backgrounds, yadda, yadda, yadda.  the one thing to be aware of with alpha is to report whether you are using 2 pi or 4 pi when calculating efficiency.  outside of that, it don't reely matter what rate you report in.  one thing to watch with the gas probes.... after sourcing, it is unnecessary to inflate the mylar against the screen,  simply having the proper percentage fill in the chamber is sufficient.  elementary, i know, but a lot of techs feel they got to blow up that there balloon.  by doing that, they greatly increase the amount of punctures.... can you imagine?  

[moke]

I enjoy the E-600 since I am able to manipulate parameters depending upon the days background and sources tests. Additionally, you are able to switch detectors in a snap.

If you are using strict protocol (characterization/final status surveys) and intend to use mandated scan methods for Alpha, then the E-600 is the desirable tool since you may program the exact counting time for fixed measurements that will maximize time expenditures. The L-2224-1 is limited in comparison to the E-600. It's nice to have an audible signal to warn when a counting time is complete too.

One problem with the E-600 is that you can't change the audible response frequency and especially mind boggling when using NaI(Tl) detection devices. Since it is important to rely on the audible response regarding detection, the L-2221 is superior when hunting for photons during field applications. It's nice to be able to adjust the audible response when conducting Gamma Walkover surveys since it will expedite the entire survey process and keep fustration to a minimum. This is extremely important when conducting final status environmental surface scan surveys.

A flexible audible adjustment feature will also increase your ability to identify the existense of elusive photons such as those inherrent with Plutonium and/or Americium. The E-600 is useless concerning this application.

As Rennhack mentioned, the L-2224-1 is a great tool. I enjoy its durability (meter casing) and reliability. The price is right too and the Ludlum Staff are great folks to work with.

If I had my way, I would have one of everything. Both intrument types have strengths and weaknesses yet they share one common headache; the fragile aluminized mylar window, photomultiplier tube, and the uncoordinated user.

Have an awesome week and stay dry!

Moke

 

[radgal]

Being at a lab (lots of different isotopes) having different meters to look for different isotopes is great.  I use NE duel scintillator probe picks up Alpha and Beta, no good for gamma goes right through.  I use Lundlum ASP2E uR to 1000 mR range,  ASP1 for gamma in the cpm range and RO20 for big Beta dose and Gamma dose rates.  Use the E600 also very versitle (sp?) instrument.  I agree with Slo Glo they work better not blown up to bursting point.  At the lab if you got the cash they can create instruments to suit what you need.  Not too bad.