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The DØ experiment enjoyed a very successful data-collection run at the Fermilab Tevatron collider between 1992 and 1996. Since then, the detector has been upgraded to take advantage of improvements to the Tevatron and to enhance its physics capabilities. We describe the new elements of the detector, including the silicon microstrip tracker, central fiber tracker, solenoidal magnet, preshower detectors, forward muon detector, and forward proton detector. The uranium/liquid-argon calorimeters and central muon detector, remaining from Run I, are discussed briefly. We also present the associated electronics, triggering, and data acquisition systems, along with the design and implementation of software specific to DØ. © 2006 Elsevier B.V. All rights reserved.

Supplement: Tantrasamgraha of Nilakantha Somayaji

We consider the ejection of one stellar system from the centre of another stellar system, representing both by Plummer models. Using the impulsive appoximation, we derive analytically the overall and differential energy changes and also the mass escape from the systems. We compare the results with those obtained for colliding systems.

Numerical simulations are performed to study the tidal effects of non-merging rapid head-on collision between a disk galaxy and a spherical galaxy. The disk consists of three components – a disk, a bulge and a halo – and the spherical galaxy is a Plummer model. The galaxies have the same dimensions with different mass ratios viz., 2, 1 and 0.5. They move in a rectilinear orbit with a relative velocity of 1000 km s−1.

A series of N-body simulations have been performed to interpret the interacting pair of galaxies VV 117 (NGC 2444/45). The galaxies have been modelled assuming a mass ratio two. The simulations use various values for the distance of closest approach and the eccentricity of the relative orbit of the pair. A plausible scenario for the tidal disruption of the less massive galaxy is proposed. NGC2444, having double the mass of NGC 2445, has undergone penetrating collision with the latter in a hyperbolic or a parabolic orbit. After the first collision, the orbit has become bound. Our results show that VV 117 has either just emerged from the first collision or are on the verge of a second collision. NGC 2445suffers considerable disruption and mass loss. NGC 2444 is not affected much. The second collision is expected to culminate in the merger of the two galaxies.

We study the tidal effects of close collisions between two spherical galaxies of various mass and mass distributions by numerical simulations. The galaxies are represented by polytropes of indices n=4 and n=0 which denote cases of highcentral concentration and uniform mass distribution respectively.The initial relative velocity of the galaxies is chosen to be 700 km s-1.The results indicate that the tidal effects are quite sensitive to both mass and mass distribution of the galaxies. The dependence oftidal capture and tidal disruption on the choice of the model and mass ratio is investigated. The classification of collisionis given for each simulation. The results also indicate that in a collision between two identical galaxies relatively more spin is imparted to the galaxies ifthey are centrally concentrated than if they are homogeneous.

Microwave oven drying of zirconium molybdate-99Mo (Zr99Mo) was investigated for preparing a gel generator for 99mTc and compared with an earlier method standardised by us using hot air for drying. With a microwave frequency of 2.45 GHz and power output of 385 W, 30 g ZrMo gel (i.e. 10 g Mo) could be satisfactorily dried for use in a generator in only 35 min compared to 16 h required in the hot air drying method. A maximum of 180 mCi 99Mo with a molybdenum content of ∼2 g per column (∼6 g of ZrMo gel) was used in the present study. The performance features of the 99mTc gel generator and the quality of pertechnetate eluate are comparable to that obtained by other well established conventional methods and thus satisfactory for medical use. The merits of reduced processing time and decay loss, apart from ease of handling a critical processing step, are the attractive features of the new method.

We study the tidal effects of a deeply penetrating collision between two spherical galaxies, one twice massive but less dense than the other, by numerical simulations. We consider the relative motion of the galaxies to be initially in a hyperbolic orbit. The collision parameters are so chosen that the primary (bigger) galaxy is just below the limit of disruption and the relative velocity of the pair is slightly in excess of the escape limit and the primary suffer greater tidal damage than the secondary. The primary develops a core halo structure and shows over all expansion while the secondary while the secondary shows contraction in the inner region and less significant expansion in the outer parts. The initially hyperbolic orbit is transformed into a parabolic orbit as a result of the collision. The result also indicate that the tidal interaction does not induce appreciable rotation in hyperbolic collision. We calculate the angle of deflection of the orbit and compare it with that computed using analytical work. The numerical work shows larger angle of deflection which is attributed to the large tidal effects of the bigger galaxy in the interpenetrating collision.

Hernquist’s (1990) mass model for spherical galaxies and bulges described by the deVaucouleur’s profile gives analytical expressions for the density profile and the potential. These have been used to derive a simple and exact analytical expression for the gravitational potential energy of a pair of interpene-trating spherical galaxies represented by this model. The results are compared with those for polytropic and Plummer models of galaxis.

Given the mismatch between supply of and demand for nuclear scientists, education in nuclear and radiochemistry has become a serious concern. The Nuclear and Radiochemistry in Chemistry Education (NRIChEd) Curriculum Project was undertaken to reintroduce the topics normally covered in a one-semester radiochemistry course into the traditional courses of a four-year chemistry major: general chemistry, organic chemistry, quantitative and instrumental analysis, and physical chemistry. NRIChEd uses a three-pronged approach that incorporates radiochemistry topics when related topics in the basic courses are covered, presents special topics of general interest as a vehicle for teaching nuclear and radiochemistry alongside traditional chemistry, and incorporates the use of non-licensed amounts of radioactive substances in demonstrations and student laboratory experiments. This approach seeks not only to reestablish nuclear science in the chemistry curriculum, but to use it as a tool for elucidating fundamental and applied aspects of chemistry as well. Moreover, because of its relevance in many academic areas, nuclear science enriches the chemistry curriculum by encouraging interdisciplinary thinking and problem solving.

A simple, semi-analytic method is developed for obtaining the orbits of galaxies undergoing fast collisions in which the galaxies are represented by Plummer models. The results are found to agree fairly well with those of N-body simulations. A simple formula for obtaining the angle of deflection is deduced. The maximum angle of deflection is 180° forV p/V esc(p)=1.00, about 36° forV p/V esc(p)=1.50, and about 18° forV p/V esc(p)=2.00, whereV p is the velocity at closest approachp, andV esc(p) is the parabolic velocity of escape atp. The angle of deflection of a pair of colliding elliptical galaxies without halos is about twice that for a pair of galaxies with halos for the same relative velocity at infinite separation.

It is shown that the fractional increase in binding energy of a galaxy in a fast collision with another galaxy of the same size can be well represented by the formula $$\xi _2 = 3({G \mathord{\left/ {\vphantom {G {M_2 \bar R}}} \right. \kern-\nulldelimiterspace} {M_2 \bar R}}) ({{M_1 } \mathord{\left/ {\vphantom {{M_1 } {V_p }}} \right. \kern-\nulldelimiterspace} {V_p }})^2 e^{ - p/\bar R} = \xi _1 ({{M_1 } \mathord{\left/ {\vphantom {{M_1 } {M_2 }}} \right. \kern-\nulldelimiterspace} {M_2 }})^3 ,$$ whereM 1,M 2 are the masses of the perturber and the perturbed galaxy, respectively,V p is the relative velocity of the perturber at minimum separationp, and $$\bar R$$ is the dynamical radius of either galaxy.

A method based on the sorption of99mTc in MEK on an acid alumina column has been investigated. A number of parameters as column dimension, amount of alumina, MEK volumes, etc. is found to affect the extent of adsorption and the final purity of99mTc solution. These parameters have been standardized and a method for rapid recovery of MEK-extracted99mTc has been developed. The final characteristics of the99mTc is found to conform to pharmacopoeia specification.

A column-extraction generator based on the adsorption of alkaline sodium molybdate on an acid alumina column is described. Generators containing 1 to 3.2 g of molybdenum /99Mo/ absorbed on 12–15 g of acid alumina, with activities ranging from 0.52 to 5.2 GBq /14 to 140 mCi/, have been prepared and evaluated. The results indicate that99mTc can be quantitatively eluted from such columns with about 10 ml of MEK. The yields were found to be in the range of 70 to 90% over 3–6 days.

A new method for the preparation of99m Tc-tin colloid has been developped using the electrolytic introduction of Sn(II) ions into 99m Tc pertechnetate solutions. The colloid has been found to be selectively trapped in the reticulo endothetial system in distribution studies with mice. The method gives a liver scanning agent that is easy to prepare and safe for administration. A kit is described for the electrolytic preparation of 99m Tc-tin colloid for use in the hospitals. The ‘kit’ is simple and economic and enables the preparation of 99m Tc-tin colloid in less than five minutes.

Labelling of N-(2,6-diethylacetanilido), N-(p-n-butylacetanilido,N-(p-methoxyacetanilido) and N-acetanilido-iminodiacetic acid analogues with99mTc obtained by MEK extraction has been studied. The acetanilido IDA analogues were synthesized using the condensation reaction between nitrilotriacetic acid anhydride and the corresponding anilines. Conditions are described to label these four HIDA analogues using MEK extracted99mTc with high and reproducible radiochemical purity.

It is shown that the merger times of a satellite galaxy moving on the periphery of the primary galaxy obtained under the impulsive and adiabatic approximations reduce to the decay time predicted by Chandrasekhar's formula for dynamical friction if the satellite galaxy is regarded as a mass point.

Presently available 113mSn.113mIn generators use high specific activity 113Sn which cannot be produced in low and medium flux research reactors even with enriched 112Sn. This paper describes a method of preparing 112Sn.113mIn generators using ll3Sn of relatively low specific activity (2—3 Ci/g) obtained by irradiation of enriched 112Sn in CIRUS. In this modified procedure, 113SnCl4 is firmly adsorbed on hydrous zirconia from 3—4 M NaCl solutions of pH 1.3 to 1.5 and the elution of 113mIn is effected by dilute HCl. The generator yields 70% of the theoretically available ll3mIn activity. 113Sn breakthrough has been consistantly less than 0.01% of the 113mIn activity. Stable zirconium contamination in the eluate has been estimated to be less than 1 ppm. The performance characteristics of different varieties of hydrous zirconia have been studied to evaluate the optimum tin loading, indium elution and soluble zirconium contamination. Generators containing upto 700 mCi of tin-113 have been prepared yielding pur...

Technetium-DTPA (diethylenetriaminepentaacetic acid) and Technetium N-(2,6-diethylacetanilido)iminodiacetic acid complexes were prepared at carrier free level and milligram levels using different methods. They were compared by paper electrophoresis. Their composition and stability constants were studied by solvent extraction.

Preparation of human serum albumin microspheres of well defined particle size distribution using a spinning disc aerosol generator has been investigated by the authors. A set up is described for bulk preparation of microspheres suitable for lung imaging. A simple procedure for denaturation of the microspheres by direct oven heating has been standardised. Methods for Tc99m labelling of these microspheres with high radiochemical yield and purity have been studied. Uptake and clearance of the labelled microspheres have been followed in experimental animals. Histopathological examination has been carried out to confirm biodegradability and safety of the microspheres. The microspheres have shown excellent lung uptake and have been found to be very safe for administration.

Energy changes in a head-on collision between two unequal Plummer model stellar systems (galaxies) are studied analytically under the impulsive approximation. The variation of the disruptive effects within and the mass escape from systems widely differing in mass and scalelength ratios are determined and some physical implications regarding the dynamical stability of the systems undergoing head-on collisions are indicated. It is found that if two systems differ considerably in size, both systems generally survive the collision if (i) the mass of the bigger is greater than about six times the mass of the smaller and (ii) the density of the smaller is more than about twenty-five times the entity of the bigger system, when the velocity at minimum separation is equal to the parabolic velocity of escape.

The authors report here a new approach for making99mTc generators based on neutron irradiation of metallic molybdates and direct elution eliminating intermediate chemical processing steps. This approach tested using zirconium molybdate was found to yield99mTc with good yield and purity. This seems to be the simplest way of making column type99mTc generator even using low flux reactors and merits further detailed evaluation.

Electrolytic labelling procedures have been reported for various99mTc radiopharmaceuticals which differ widely in the choice of the electrodes, working pH, applied voltage and the quantity of current passed. The authors have studied the electrolytic labelling of99mTc EHDP, gluconate and glucoheptonate with MEK extracted99mTc using tin electrodes under different experimental conditions. The results have, shown that these compounds can be efficiently labelled with99mTc in a single step procedure avoiding multiple pH adjustments. Labelling of human serum albumin microspheres suitable for lung imaging with99mTc by the electrolytic method is also reported.

A procedure for preparation of a sterile closed system generator for99mTc based on conversion to zirconium molybdate of99Mo produced by neutron activation is reported. The generator is sterilized by autoclaving.99mTc is eluted using 0.9% NaCl with high yield and purity in successive elutions.

Zero-velocity curves perpendicular to the orbital plane are computed for a close pair of interacting galaxies having density distribution that of a polytrope of indexn=4. An analytical formulation for computing the zero-velocity surfaces is suggested.

Solvent extraction separation of99mTc from99Mo using methyl ethyl ketone(MEK) has been found to be an effective method of obtaining99mTc of medicinal purity from low specific activity99Mo. The authors have investigated the effect of alkali and molybdenum concentration on the extraction of99Mo and99mTc into methyl ethyl ketone. The possibility of methyl ethyl ketone forming enol and condensation products and its effect on the final extraction efficiency and purity of99mTc has been studied. Sodium molybdate has been found to have a good salting out effect on99mTc pertechnetate and hence99mTc extraction can be better accomplished from low specific activity99Mo solutions. The ketone seems to form traces of condensation products in the extraction procedure. These have been found to be coextracted with99mTc into MEK but did not affect the extractability of99mTc. It was observed that neutral alumina column removes these condensation products from MEK containing99mTc. Alternately these could be filtered off by acidification of the final aqueous99mTc solution. The studies indicate that under optimum experimental conditions methyl ethyl ketone separates99mTc from99Mo with high efficiency and yields99mTc of high purity suitable for use in nuclear medicine in the form of various labelled compounds.

Experiments performed very deep underground in the gold mines in India and in South Africa are analyzed to yield tau/sub N/..mu..>1.8 x 10/sup 30/ yr and tau/sub N/K>10/sup 30/ yr for the baryon-number-nonconserving decay of bound nucleons into muonic and kaonic channels, respectively. New experiments capable of improving these limits by more than an order of magnitude are suggested.

The dynamics of an encounter between two galaxies is discussed. Generally in galactic encounter, on account of the tidal forces, the binding energies of the galaxies increase and hence their relative orbital energy decreases. The former has disruptive effects on galaxies and the latter may lead to the merging of galaxies under certain circumstances. Studies of these processes and their consequences have been reviewed. The role of the tidal forces in the dynamical evolution of clusters of galaxies and in the formation of intergalactic filaments and ring galaxies is discussed.

The process of energy transfer in galaxy interactions is discussed with particular reference to mergers. The work done on the determination of the merger time of binary galaxies and the decay time of satellite galaxies is reviewed. Estimates made for the merger time of some observed pairs are given.