D0 General Support: The Use of Programmable Logic Controllers (PLCS) at D0

With the exception of control of heating, ventilation, and air conditioning (HVAC) ventilation fans, and their shutdown in the case of smoke in the ducts, all implementations of Programmable Logic Controllers (PLCs) in Dzero have been made within the fundamental premise that no uncertified PLC apparatus shall be entrusted with the safety of equipment or personnel. Thus although PLCs are used to control and monitor all manner of intricate equipment, simple hardware interlocks and relief devices provide basic protection against component failure, control failure, or inappropriate control operation. Nevertheless, this report includes two observations as follows: (1) It may be prudent to reconfigure the link between the Pyrotronics system and the HVAC system such that the Pyrotronics system provides interlocks to the ventilation fans instead of control inputs to the uncertified HVAC PLCs. Although the Pyrotronics system is certified and maintained to life safety standards, the HVAC system is not. A hardware or software failure of the HVAC system probably should not be allowed to result in the situation where the ventilation fans in a smoke filled duct continue to operate. Dan Markley is investigating this matter. (2) It may also be prudent to examine the network security of those systems connected to the Fermilab WAN (HVAC, Cryo, and Solenoid Controls). Even though the impact of a successful hack might only be to operations, it might nevertheless be disruptive and could be expensive. The risks should perhaps be analyzed. One of the most attractive features of these systems, from a user's viewpoint, is their unlimited networking. The unlimited networking that makes the systems so convenient to legitimate access also makes them vulnerable to illegitimate access

Paramecia With Extra Contractile Vacuoles

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Counterfactuality, Definiteness, and Bell's Theorem

We show counterfactual definiteness separates classical from quantum physics, by analysing Bell's Theorem. By comparing what it prohibited by various interpretations, we show most interpretations just require counterfactual semi-definiteness (the definiteness of possible options available after a measurement event), rather than full counterfactual indefiniteness. While less definite than classical counterfactual definiteness, it allows us a far more sophisticated tool to consider the physical interpretation of multi-valued variables in a not yet done. Working from this, we further consider its relation to how counterfactual possibilities interact.Comment: 5+1 pages, edited for clarity and concisenes

Comment on "Experimentally adjudicating between different causal accounts of Bell-inequality violations via statistical model selection"

In a recent paper (Phys. Rev. A 105, 042220 (2022)), Daley et al claim that superdeterministic models are disfavoured against standard quantum mechanics, because such models overfit the statistics of a Bell-type experiment which the authors conducted. We argue here that their claim is based on a misunderstanding of what superdeterministic models are.Comment: 4 pages, no figure

Comment on ``Scheme of the arrangement for attack on the protocol BB84"

In a recent paper (Scheme of the arrangement for attack on the protocol BB84, Optik 127(18):7083-7087, Sept 2016), a protocol was proposed for using weak measurement to attack BB84. This claimed the four basis states typically used could be perfectly discriminated, and so an interceptor could obtain all information carried. We show this attack fails when considered using standard quantum mechanics, as expected - such ``single-shot" quantum state discrimination is impossible, even using weak measurement.Comment: 3 pages, 1 figure, accepted for publication by Opti

Comment on "Why interference phenomena do not capture the essence of quantum theory" by Catani et al

It was recently argued by Catani et al that it is possible to reproduce the phenomenology of the double-slit experiment with a deterministic, local, and classical model (arXiv:2111.13727). The stated aim of their argument is to falsify the claim made by Feynman (in his third book of Lectures on Physics) that the double-slit experiment is "impossible, absolutely impossible, to explain in any classical way" and that it "contains the only mystery" of quantum mechanics. We here want to point out some problems with their argument, and defend Feynman's position.Comment: 3 pages, no figures, comments welcom