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I was reading in ECC memory about how alpha particles cause errors in computer memory (roughly 1 per 10GB per hour). But alpha particles are usually stopped by a sheet of paper. Most of the case on my computers is metal (plastic front and top). Also, my ECC memory is encased in a metal heat spreader. Shouldn't the case and heat spreader stop alpha particles? Bubba73 You talkin' to me? 06:20, 11 March 2019 (UTC)
BTW, our soft error#Alpha particles from package decay discusses in more detail how attempts are made to reduce the risk of alpha particle emissionsElectrical or magnetic interference inside a computer system can cause a single bit of dynamic random-access memory (DRAM) to spontaneously flip to the opposite state. It was initially thought that this was mainly due to alpha particles emitted by contaminants in chip packaging material, but research has shown that the majority of one-off soft errors in DRAM chips occur as a result of background radiation, chiefly neutrons from cosmic ray secondaries.
P.S. I'm not sure where in our article you got the figure you cited. The only figures I see are for all errors, rather than those attributed to alpha particles. As said, it says most of these appear to be caused by neutrons from cosmic rays. Nil Einne (talk) 09:30, 11 March 2019 (UTC)Soft errors became widely known with the introduction of dynamic RAM in the 1970s. In these early devices, chip packaging materials contained small amounts of radioactive contaminants. Very low decay rates are needed to avoid excess soft errors, and chip companies have occasionally suffered problems with contamination ever since. It is extremely hard to maintain the material purity needed. Controlling alpha particle emission rates for critical packaging materials to less than a level of 0.001 counts per hour per cm2 (cph/cm2) is required for reliable performance of most circuits. For comparison, the count rate of a typical shoe's sole is between 0.1 and 10 cph/cm2. Package radioactive decay usually causes a soft error by alpha particle emission. The positive charged alpha particle travels through the semiconductor and disturbs the distribution of electrons there. If the disturbance is large enough, a digital signal can change from a 0 to a 1 or vice versa. In combinational logic, this effect is transient, perhaps lasting a fraction of a nanosecond, and this has led to the challenge of soft errors in combinational logic mostly going unnoticed. In sequential logic such as latches and RAM, even this transient upset can become stored for an indefinite time, to be read out later. Thus, designers are usually much more aware of the problem in storage circuits.
So I guess in that way, you are right that it could be regarded as alpha particles at some ultimate level. But from what I read, alpha or other charged particles coming from neutrons coming from cosmic rays are normally considered separately from alpha particles coming from alpha decay of the chip packaging. And it's not clear to me if we even know what percentage of errors are likely to be coming from alpha particles compared to other charged particles, arising from neutron capture. Also, I still don't see the relevance of the heat spreader or case in stopping alpha particle emissions from neutron capture happening within the chip. Nil Einne (talk) 09:59, 11 March 2019 (UTC)Neutrons are uncharged and cannot disturb a circuit on their own, but undergo neutron capture by the nucleus of an atom in a chip. This process may result in the production of charged secondaries, such as alpha particles and oxygen nuclei, which can then cause soft errors.
In order to edit an existing MS Word footer I seem to need to go Insert >>> Header & Footer >>> Footer >>> Edit Footer. For years having to click 'Insert' to access an existing footer has irritated my obsessive compulsive behavior mode. Is there a more logical way? Hayttom (talk) 11:12, 11 March 2019 (UTC)