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Optimization of a muon collider interaction region with respect to detector backgrounds and the heat load to the cryogenic systems
In a 2 X 2 TeV {mu}{sup +}{mu}{sup -} Collider almost 15 MW of power is deposited in the machine and detector components due to the unavoidable {mu}{r_arrow}{ital e{nu}{nu}{anti {nu}}} decays. The resulting heat load to the cryogenic systems and the background levels in the collider detectors significantly exceed those in any existing or designed hadron and {ital e}{sup +}{ital e}{sup -} colliders. This paper shows that by carefully designing the final focus system, by embedding shielding and by taking other protective measures the heat load and backgrounds can be mitigated by several orders of magnitude
A topos for algebraic quantum theory
The aim of this paper is to relate algebraic quantum mechanics to topos
theory, so as to construct new foundations for quantum logic and quantum
spaces. Motivated by Bohr's idea that the empirical content of quantum physics
is accessible only through classical physics, we show how a C*-algebra of
observables A induces a topos T(A) in which the amalgamation of all of its
commutative subalgebras comprises a single commutative C*-algebra. According to
the constructive Gelfand duality theorem of Banaschewski and Mulvey, the latter
has an internal spectrum S(A) in T(A), which in our approach plays the role of
a quantum phase space of the system. Thus we associate a locale (which is the
topos-theoretical notion of a space and which intrinsically carries the
intuitionistic logical structure of a Heyting algebra) to a C*-algebra (which
is the noncommutative notion of a space). In this setting, states on A become
probability measures (more precisely, valuations) on S(A), and self-adjoint
elements of A define continuous functions (more precisely, locale maps) from
S(A) to Scott's interval domain. Noting that open subsets of S(A) correspond to
propositions about the system, the pairing map that assigns a (generalized)
truth value to a state and a proposition assumes an extremely simple
categorical form. Formulated in this way, the quantum theory defined by A is
essentially turned into a classical theory, internal to the topos T(A).Comment: 52 pages, final version, to appear in Communications in Mathematical
Physic
`What is a Thing?': Topos Theory in the Foundations of Physics
The goal of this paper is to summarise the first steps in developing a
fundamentally new way of constructing theories of physics. The motivation comes
from a desire to address certain deep issues that arise when contemplating
quantum theories of space and time. In doing so we provide a new answer to
Heidegger's timeless question ``What is a thing?''.
Our basic contention is that constructing a theory of physics is equivalent
to finding a representation in a topos of a certain formal language that is
attached to the system. Classical physics uses the topos of sets. Other
theories involve a different topos. For the types of theory discussed in this
paper, a key goal is to represent any physical quantity with an arrow
\breve{A}_\phi:\Si_\phi\map\R_\phi where \Si_\phi and are two
special objects (the `state-object' and `quantity-value object') in the
appropriate topos, .
We discuss two different types of language that can be attached to a system,
. The first, \PL{S}, is a propositional language; the second, \L{S}, is
a higher-order, typed language. Both languages provide deductive systems with
an intuitionistic logic. With the aid of \PL{S} we expand and develop some of
the earlier work (By CJI and collaborators.) on topos theory and quantum
physics. A key step is a process we term `daseinisation' by which a projection
operator is mapped to a sub-object of the spectral presheaf \Sig--the topos
quantum analogue of a classical state space. The topos concerned is \SetH{}:
the category of contravariant set-valued functors on the category (partially
ordered set) \V{} of commutative sub-algebras of the algebra of bounded
operators on the quantum Hilbert space \Hi.Comment: To appear in ``New Structures in Physics'' ed R. Coeck
Intuitionistic quantum logic of an n-level system
A decade ago, Isham and Butterfield proposed a topos-theoretic approach to
quantum mechanics, which meanwhile has been extended by Doering and Isham so as
to provide a new mathematical foundation for all of physics. Last year, three
of the present authors redeveloped and refined these ideas by combining the
C*-algebraic approach to quantum theory with the so-called internal language of
topos theory (see arXiv:0709.4364). The goal of the present paper is to
illustrate our abstract setup through the concrete example of the C*-algebra of
complex n by n matrices. This leads to an explicit expression for the pointfree
quantum phase space and the associated logical structure and Gelfand transform
of an n-level system. We also determine the pertinent non-probabilisitic
state-proposition pairing (or valuation) and give a very natural
topos-theoretic reformulation of the Kochen--Specker Theorem. The essential
point is that the logical structure of a quantum n-level system turns out to be
intuitionistic, which means that it is distributive but fails to satisfy the
law of the excluded middle (both in opposition to the usual quantum logic).Comment: 26 page
'Education, education, education' : legal, moral and clinical
This article brings together Professor Donald Nicolson's intellectual interest in professional legal ethics and his long-standing involvement with law clinics both as an advisor at the University of Cape Town and Director of the University of Bristol Law Clinic and the University of Strathclyde Law Clinic. In this article he looks at how legal education may help start this process of character development, arguing that the best means is through student involvement in voluntary law clinics. And here he builds upon his recent article which argues for voluntary, community service oriented law clinics over those which emphasise the education of students
The JCMT Gould Belt Survey: evidence for radiative heating and contamination in the W40 complex
We present SCUBA-2 450 μm and 850 μm observations of the W40 complex in the Serpens-Aquila region as part of the James Clerk Maxwell Telescope (JCMT) Gould Belt Survey (GBS) of nearby star-forming regions. We investigate radiative heating by constructing temperature maps from the ratio of SCUBA-2 fluxes using a fixed dust opacity spectral index, β = 1.8, and a beam convolution kernel to achieve a common 14.8 arcsec resolution. We identify 82 clumps ranging between 10 and 36 K with a mean temperature of 20 ± 3 K. Clump temperature is strongly correlated with proximity to the external OB association and there is no evidence that the embedded protostars significantly heat the dust. We identify 31 clumps that have cores with densities greater than 105cm-3. 13 of these cores contain embedded Class 0/I protostars. Many cores are associated with bright-rimmed clouds seen in Herschel 70 μm images. From JCMT HARP observations of the 12CO 3-2 line, we find contamination of the 850 μm band of up to 20 per cent. We investigate the free-free contribution to SCUBA-2 bands from large-scale and ultracompact HII regions using archival VLA data and find the contribution is limited to individual stars, accounting for 9 per cent of flux per beam at 450 μm or 12 per cent at 850 μm in these cases. We conclude that radiative heating has potentially influenced the formation of stars in the Dust Arc sub-region, favouring Jeans stable clouds in the warm east and fragmentation in the cool west
Conducting Assessments in Technology Needs: From Assessment to Implementation
Practitioners with an expertise in assistive technology and technology assessments are in demand to be full participants in the selection, planning, and implementation of instruction for students with mild disabilities. Frequently, practitioners with knowledge of assistive technology are assigned to evaluate students with sensory, physical, language, or severe disabilities. Our article highlights aspects of technology assessments and progress monitoring that can be used for students with mild disabilities. Given the impact that technology integration can have on the access that students with mild disabilities have to the general education classroom, we argue that all practitioners should be cognizant of protocols for assistive technology assessment and evaluation and that all evaluation teams should include an assistive technology specialist.Yeshttps://us.sagepub.com/en-us/nam/manuscript-submission-guideline
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