yoctonewton

[neufer]

NIST sensor measures yoctonewton forces fast
Science Centric | 2 September 2010 17:16 GMT

<<Physicists at the National Institute of Standards and Technology (NIST) have used a small crystal of ions to detect forces at the scale of yoctonewtons. A newton is already a small unit: roughly the force of Earth's gravity on a small apple. A yoctonewton is one septillionth of a newton. Measurements of slight forces - one yoctonewton is equivalent to the weight of a single copper atom on Earth - can be useful in force microscopy, nanoscale science, and tests of fundamental physics theories.

Measurements of vanishingly small forces typically are made with tiny mechanical oscillators, which vibrate like guitar strings. The new NIST sensor, described in Nature Nanotechnology, is even more exotic - a flat crystal of about 60 beryllium ions trapped inside a vacuum chamber by electromagnetic fields and cooled to 500 millionths of a degree above absolute zero with an ultraviolet laser. The apparatus was developed over the past 15 years for experiments related to ion plasmas and quantum computing. In this case, it was used to measure yoctonewton-scale forces from an applied electric field. In particular, the experiment showed that it was possible to measure about 390 yoctonewtons in just one second of measurement time, a rapid speed that indicates the technique's high sensitivity. Sensitivity is an asset for practical applications.

The previous force measurement record with this level of sensitivity was achieved by another NIST physicist who measured forces 1,000 times larger, or 500 zeptonewtons in one second of measurement time using a mechanical oscillator. Previous NIST research indicated that a single trapped ion could sense forces at yoctonewton scales but did not make calibrated measurements.

The ion sensor described in Nature Nanotechnology works by examining how an applied force affects ion motion, based on changes in laser light reflected off the ions. A small oscillating electric field applied to the crystal causes the ions to rock back and forth; as the ions rock, the intensity of the reflected laser light wobbles in sync with the ion motion. A change in the amount of reflected laser light due to the force is detectable, providing a measure of the ions' induced motion using a principle similar to the one at work in a police officer's radar gun. The technique is highly sensitive because of the low mass of the ions, strong response of charged particles to external electric fields, and ability to detect nanometre-scale changes in ion motion.>>

[Beyond]

Way back last century, i was in the signal corps of the Army in an exotic south-east locale called Vietnam. Somewhere amongst the extra communication courses that i was takeing was the definition of 1-decibel(db). 1 db was described at being the equivalent sound level of a mouse pooping on a tissue paper 20 feet away. I have never tried to test that explanation and have accepted that description as true. Our antenna's would normally receive signals from other places at about -60db and if they just went through our house we would amplify them to +7db and send them on their way.
WOW! 7db. That's 7 times as loud as a mouse pooping on a tissue paper 20 feet away. I think we operated at about the same level, or just higher than SETI, but i'm not sure about that. We always refered to our signal levels as being "in the mud" and of course SETI was a receive only setup.
The definition of a yoctonewton reminded me of all that "pleasent" stuff.

[neufer]

Way back last century, i was in the signal corps of the Army in an exotic south-east locale called Vietnam.

I too was a specialist in the signal corps during Vietnam (1969-71)
but I was lucky enough to do my tour of duty at White Sands Missile Range.

Somewhere amongst the extra communication courses that i was taking was the definition of 1-decibel(db). 1 db was described at being the equivalent sound level of a mouse pooping on a tissue paper 20 feet away.

Owls are trained to hear such things.
(Do mice really use tissue paper? Did the Army really use feet?)

I have never tried to test that explanation and have accepted that description as true.

It is hard enough potty training a two year old.

Our antenna's would normally receive signals from other places at about -60db and if they just went through our house we would amplify them to +7db and send them on their way.
WOW! 7db. That's 7 times as loud as a mouse pooping on a tissue paper 20 feet away.

5 times (=10^0.7) as loud actually(; the Bel system is logarithmic to the base 10).

I think we operated at about the same level, or just higher than SETI, but i'm not sure about that. We always referred to our signal levels as being "in the mud" and of course SETI was a receive only setup.

Perhaps our next radio signal into space should be of a mouse pooping on tissue paper.
That oughta scare the bad aliens away.

[Chris Peterson]

WOW! 7db. That's 7 times as loud as a mouse pooping on a tissue paper 20 feet away.

5 times (=10^0.7) as loud actually(; the Bel system is logarithmic to the base 10).

I thought about responding to this, but decided it's just way too complicated! "Loudness" is a measure of our physiological response. And loudness is itself logarithmic. So what you are actually calculating is the difference in sound pressure. And there are different decibel scales for that, to accommodate our actual response, both in terms of intensity and frequency.

As far as pooping mice... well, in terms of acoustic decibels, 0dB is defined as the threshold of hearing. If you can just hear that mouse, I guess 1dB might be reasonable. But I'm guessing that the sound of a pooping mouse is probably measured in negative decibels.

Comparing acoustic decibels, which describe ratios of sound pressure, to signal strength decibels in a radio system, is pretty much comparing apples to oranges.

[neufer]

WOW! 7db. That's 7 times as loud as a mouse pooping on a tissue paper 20 feet away.

5 times (=10^0.7) as loud actually(; the Bel system is logarithmic to the base 10).

I thought about responding to this, but decided it's just way too complicated! "Loudness" is a measure of our physiological response. And loudness is itself logarithmic. So what you are actually calculating is the difference in sound pressure. And there are different decibel scales for that, to accommodate our actual response, both in terms of intensity and frequency.

As far as pooping mice... well, in terms of acoustic decibels, 0dB is defined as the threshold of hearing. If you can just hear that mouse, I guess 1dB might be reasonable. But I'm guessing that the sound of a pooping mouse is probably measured in negative decibels.

Correction: 4 times (=10^0.7-0.1) as loud actually.

Comparing acoustic decibels, which describe ratios of sound pressure, to signal strength decibels in a radio system, is pretty much comparing apples to oranges.

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dB(SPL): dB (sound pressure level) – for sound in air and other gases, relative to 20 micropascals (μPa) = 2×10⁻⁵ Pa, the quietest sound a human can hear. This is roughly the sound of a mosquito flying 3 metres away. This is often abbreviated to just "dB", which gives some the erroneous notion that "dB" is an absolute unit by itself.
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dB(A), dB(B), and dB(C): These symbols are often used to denote the use of different weighting filters, used to approximate the human ear's response to sound, although the measurement is still in dB (SPL). These measurements usually refer to noise and noisome effects on humans and animals, and are in widespread use in the industry with regard to noise control issues, regulations and environmental standards. Compare dBc, used in telecommunications.
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dBc: – relative to carrier—in telecommunications, this indicates the relative levels of noise or sideband peak power, compared with the carrier power. Compare dBC, used in acoustics.
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dBm: dB(mW) – power relative to 1 milliwatt. When used in audio work the milliwatt is referenced to a 600 ohm load, with the resultant voltage being 0.775 volts. When used in the 2-way radio field, the dB is referenced to a 50 ohm load, with the resultant voltage being 0.224 volts. There are times when spec sheets may show the voltage & power level e.g. −120 dBm = 0.224 microvolts.
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[Beyond]

Owls are trained to hear such things

You don't have to train owls to hear, they just naturally hear everything. Ask Owlice. She'll tell you that when you post something about Her, she can hear it eight forums away and will Swoop in, sharpened Talons at the ready, in case they are needed. Now, how many packages of bandages have you gone through this year, Neufer