hmm, 28 particles in three years, maybe not. That pretty much misrepresents the full article.
From section 4: "The factor of proportionality between the antiproton flux and the number of detected antiproton candidates, corrected for selection efficiencies and acquisition time, is by definition the gathering power of the apparatus.
The apparatus gathering power was calculated to be significantly reduced with respect to the geometric factor (http://pamela.roma2.infn.it/index.php?option=com_content&task=view&id=28&Itemid=256
The actual PAMELA instrument is fairly small(roughly 1.3 m x.5m) and has esentially no intake manifold.
From section 5: During about 850 days of data acquisition (from 2006 July to 2008 December), 28 trapped antiprotons were identified within the kinetic energy range 60–750 MeV. Events with geomagnetic McIlwain coordinates (McIlwain 1961) in the range 1.1 L 1.3 and B 0.216 G were selected, corresponding to the SAA. The fractional livetime spent by PAMELA in this region amounts to the 1.7% ( 4.6 109 s).
My understanding is that that 850 days is time live for the instrument and 1.7% is percent of time in the SAA at geomagnetic ranges of interest. Right? So, 4.6X10^9 seconds works out to about 145 years. 1.7% of 850 days is 14.25 days. Quite a discreapency. Can someone else shed light?
So, you have an instrument with a very small physical intake and no collection system. Limited time at the target site as well. Given these factors, I would have to imagine that a larger more complex system could collect meaningful volumes. Might want to give that Buzzard ram scoop idea a second look.
The paper from Draper: I like their estimations of collection rates. There should have been better treatment of power requirements vs. yeilds of the system. And, they at least could have given a nod to the Sci-Fi popularization of the same idea.
Now, lets wait too see some realistic propulsion system concepts.
Slashdot Mirror
hmm, 28 particles in three years, maybe not. That pretty much misrepresents the full article.
From section 4:
"The factor of proportionality between the antiproton flux and the number of detected antiproton
candidates, corrected for selection efficiencies and acquisition time, is by definition the gathering
power of the apparatus.
The apparatus gathering power was calculated to be significantly
reduced with respect to the geometric factor (http://pamela.roma2.infn.it/index.php?option=com_content&task=view&id=28&Itemid=256
The actual PAMELA instrument is fairly small(roughly 1.3 m x .5m) and has esentially no intake manifold.
From section 5:
During about 850 days of data acquisition (from 2006 July to 2008 December), 28 trapped
antiprotons were identified within the kinetic energy range 60–750 MeV. Events with geomagnetic
McIlwain coordinates (McIlwain 1961) in the range 1.1 L 1.3 and B 0.216 G were selected,
corresponding to the SAA. The fractional livetime spent by PAMELA in this region amounts to
the 1.7% ( 4.6 109 s).
My understanding is that that 850 days is time live for the instrument and 1.7% is percent of time in the SAA at geomagnetic ranges of interest. Right? So, 4.6X10^9 seconds works out to about 145 years. 1.7% of 850 days is 14.25 days. Quite a discreapency. Can someone else shed light?
So, you have an instrument with a very small physical intake and no collection system. Limited time at the target site as well. Given these factors, I would have to imagine that a larger more complex system could collect meaningful volumes. Might want to give that Buzzard ram scoop idea a second look.
The paper from Draper:
I like their estimations of collection rates. There should have been better treatment of power requirements vs. yeilds of the system. And, they at least could have given a nod to the Sci-Fi popularization of the same idea.
Now, lets wait too see some realistic propulsion system concepts.