Hadron Physics with CLAS12

Hadron spectroscopy has been an essential part of the physics program with the CLAS detector in experimental Hall B at Jefferson Lab. Production of baryon and meson resonances with high energy (polarized) electron and photon beams was studied on a veriety of targets, ranging from hydrogen to lead. Physics topics of interest include: investigation of the spectrum of baryon and meson resonances, transition form-factors, meson-nucleon couplings (mesons in nuclei), and search for exotic and missing states. With the 12 GeV upgrade of the CEBAF machine, hadron spectroscopy in Hall B will be extended to a new domain of higher mass resonances and the range of higher transferred momentum using up to 11 GeV electron beams and the upgraded CLAS12 detector. In this paper a brief description of the CLAS12 detector and the physics program adopted for 12 GeV with emphasis to baryon and meson spectroscopy is presented.Comment: Hadron-09 proceedings, 8 pages, 5 figure

On Theta-palindromic Richness

In this paper we study generalization of the reversal mapping realized by an arbitrary involutory antimorphism $\Theta$. It generalizes the notion of a palindrome into a $\Theta$-palindrome -- a word invariant under $\Theta$. For languages closed under $\Theta$ we give the relation between $\Theta$-palindromic complexity and factor complexity. We generalize the notion of richness to $\Theta$-richness and we prove analogous characterizations of words that are $\Theta$-rich, especially in the case of set of factors invariant under $\Theta$. A criterion for $\Theta$-richness of $\Theta$-episturmian words is given together with other examples of $\Theta$-rich words.Comment: 14 page

About a certain NP complete problem

In this article we introduce the concept of special decomposition of a set and the concept of special covering of a set under such a decomposition. We study the conditions for existence of special coverings of the sets, under the special decomposition of the set. These conditions of formulated problem have important applications in the field of satisfiability of Boolean functions. Our goal is to study the relationship between sat CNF problem and the problem of existance of special covering of the set. We also study the relationship between classes of computational complexity by searching for special coverings of the sets. We prove, that the decidability of sat CNF problem, in polynomial time reduces to the problem of existence of a special covering of a set. We also prove, that the problem of existence of a special covering of a set, in polynomial time reduces to the decidability of the sat CNF problem. Therefore, the mentioned problems are polynomially equivalent. And then, the problem of existence of a special covering of a set is NP-complete problem

CMOS VLSI correlator design for radio-astronomical signal processing : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Engineering at Massey University, Auckland, New Zealand

Multi-element radio telescopes employ methods of indirect imaging to capture the image of the sky. These methods are in contrast to direct imaging methods whereby the image is constructed from sensor measurements directly and involve extensive signal processing on antenna signals. The Square Kilometre Array, or the SKA, is a future radio telescope of this type that, once built, will become the largest telescope in the world. The unprecedented scale of the SKA requires novel solutions to be developed for its signal processing pipeline one of the most resource-consuming parts of which is the correlator. The SKA uses the FX correlator construction that consists of two parts: the F part that translates antenna signals into frequency domain and the X part that cross-correlates these signals between each other. This research focuses on the integrated circuit design and VLSI implementation issues of the X part of a very large FX correlator in 28 nm and 130 nm CMOS. The correlator’s main processing operation is the complex multiply-accumulation (CMAC) for which custom 28 nm CMAC designs are presented and evaluated. Performance of various memories inside the correlator also affects overall efficiency, and input-buffered and output-buffered approaches are considered with the goal of improving upon it. For output-buffered designs, custom memory control circuits have been designed and prototyped in 130 nm that improve upon eDRAM by taking advantage of sequential access patterns. For the input-buffered architecture, a new scheme is proposed that decreases the usage of the input-buffer memory by a third by making use of multiple accumulators in every CMAC. Because cross-correlation is a very data-intensive process, high-performance SerDes I/O is essential to any practical ASIC implementation. On the I/O design, the 28 nm full-rate transmitter delivering 15 Gbps per lane is presented. This design consists of the scrambler, the serialiser, the digital VCO with analog fine-tuning and the SST driver including features of a 4-tap FFE, impedance tuning and amplitude tuning