The Wiper Gold competes against the Capintec Caprac and other single-well counters on form factor, footprint, and bench presence. What separates them is qualitative — capabilities that a spec column can’t convey but that change the actual work. Here are four of them, made visceral.
Two single-well wipe-test counters can look identical on a desk. Buyers who don’t use one every day often default to the lower-priced option. This walkthrough is for that buyer — the four capabilities below are the differences that show up after the purchase order is signed, and the differences that justify the choice up front.
4096 channels vs. the competitive deck
A multi-channel analyzer (MCA) divides the 0–1 MeV energy range into individual “channels.” More channels = finer resolution = sharper peaks, cleaner identifications, more reliable analysis. The Wiper Gold has 4096 channels. Most competitors at this price point have 256 or 64. Here’s the difference, applied to a thing your eyes already know how to evaluate.
Click the buttons above to see what 256 and 64 channels do to the same image. The detail you lose isn’t cosmetic — in a real spectrum it’s the difference between resolving Tc-99m (140 keV) cleanly from a Mo-99 breakthrough sitting next to it, or seeing them as one indistinct hump. It’s the difference between identifying an unknown contamination from its photopeak signature, or shrugging.
1″¼ deep well in a 2″⅛ long crystal vs. 1.5″ deep well in a 1.75″ long crystal — and why F-18 cares
Gamma rays don’t deposit their energy in a crystal by magic. They have to travel through enough crystal mass to interact — the higher the energy, the more crystal it takes. Stopping power is everything at high energies. The Wiper Gold uses a 1″⅛ × 2″⅛ NaI(Tl) crystal with a 0.67″ wide × 1″¼-deep well, leaving ⅞ of an inch of crystal directly below the sample. The Capintec Caprac uses a 1.5″×1.75″ detector with a 0.67″×1.5″ well — the well runs nearly the full length of the crystal, leaving only 0.25″ of crystal below the sample. 3.5× more stopping mass where it matters most.
The asymmetric design is deliberate. The Wiper Gold detector is longer than it is wide — while Capintec’s is wider than it is long. Capintec’s extra side-of-well crystal might sound like an advantage, but side mass stops contributing usefully above I-125 (35 keV). At clinical-isotope energies — Tc-99m (140 keV), F-18 (511 keV), Cs-137 (662 keV), Co-57 (122 keV) — gammas going out the side interact even in a thin crystal. So Capintec’s extra side mass is wasted at every energy you actually count. What matters at high energies is the crystal mass below the sample, where gammas heading downward have to travel through enough material to be stopped. LTI puts the crystal where it does the most work.
~8% stopped — 1 of 12
0.25 in.
of crystal below the sample
The well runs nearly the full length of the detector. Almost no crystal mass below the sample to stop high-energy gammas. F-18, Cs-137, and Co-57 photons pass straight through the thin crystal floor without interacting. Lost counts. Lower DPM accuracy. Underreported activity at the energies that matter for PET work.
~25% stopped — 3 of 12
⅞ in.
of crystal below the sample
3.5× the stopping mass below the well. High-energy gammas have meaningfully more material to interact with on their way through. The result: > 80 % efficiency on Co-57 and meaningfully better F-18 / 511 keV performance than the wider-but-shorter Capintec design.
This isn’t marketing. It’s the geometry of how a NaI(Tl) crystal actually works. Look at the crystal-mass numbers on any single-well counter spec sheet — the ones that publish them. Then look at the published efficiency curves at 511 keV. The math always lines up. We’re just one of the few willing to put both numbers on the page.
AutoSpect™ Spectrum Compensation vs. flat-percentage approximations
Most counters report DPM by applying a single flat percentage efficiency per isotope — a fudge factor the manufacturer pre-calculated for the isotopes shipped in the library. Want to count an isotope not in the library? You can manually enter your own fudge factor — and live with whatever accuracy that produces. The Wiper Gold doesn’t work that way.
Most counters at this price point
Result: approximate DPM. Often good enough for Pass/Fail at trigger. Not good enough for inspector-grade reporting on isotopes the manufacturer didn’t pre-calibrate.
Wiper Gold
Result: real DPM on any isotope you put in. Inspector-grade. Defensible against any audit. No isotope-specific calibrated-source purchase required for routine work.
The visible difference shows up on the spectrum itself. Below: the same Cs-137 measurement with and without AutoSpect applied. The corrected version is what the spectrum would look like if the sample were perfectly captured by the crystal at every energy — that’s the spectrum your inspector and your isotope-ID software actually want to see. From there, the per-isotope Spectrum Compensation step does the math from gammas to disintegrations, and the result is DPM you can trust.
Full PHA toolkit — built into the wipe counter
A standalone laboratory MCA — a dedicated rack-mount instrument with full Pulse Height Analysis (PHA), Region of Interest (ROI) selection, peak identification, FWHM calculation, baseline subtraction, and dead-time correction — runs $15,000 to $25,000 on the open market. Most labs that need MCA-grade analysis budget for a separate piece of equipment, on a separate bench, with separate maintenance. The Wiper Gold has all of that built into the wipe counter itself.
Drag region edges across the live spectrum, define multiple ROIs simultaneously, get integrated counts and net activity per region.
Identify peaks against the stored isotope library. Useful for unknown-contamination forensics on routine wipes.
Full Width at Half Maximum measurement on any peak in the spectrum. Resolution diagnostics, calibration verification, detector aging tracking.
Automated background subtraction across user-defined regions. Cleaner peak integration, more accurate net counts.
Automatic correction at high count rates. The Wiper Gold handles count rates well into the hundreds of thousands of cps without paralysis.
Cursor-driven energy/channel readout. Useful for spectrum interpretation, calibration verification, peak identification on the fly.
The MCA isn’t a feature on a feature list. It’s a separate instrument’s worth of capability shipping in the same chassis as the wipe counter — for the same total cost as a single-well wipe counter without an MCA. Customers who don’t need PHA capability never use it. Customers who do (radiation safety officers, university research labs, nuclear pharmacies handling unusual contamination) report it as the single feature that justifies the purchase.
Spec sheets compare on numbers that are easy to print — channel count, well dimensions, weight, dimensions, calibration source. The four capabilities above are the differences that matter day-to-day, after the instrument is on the bench. They’re harder to explain in a column-vs-column comparison, which is why most buyers default to price.
If you want to talk through your specific application — what isotopes you count, what energy range you actually need, whether the MCA capability matters for your QA program — call us. We’re the people who designed the instrument, not a sales channel.