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Low Temperature Thermal Expansion of G-10 Plastic and Mylar

Description: This engineering note is a summary of test information and conclusions from the thermal expansion tests conducted at D-O during the fall of 1992. Each test was conducted separately but using the same basic procedure and equipment. While information on material properties at room temperature and above for these products is quite well doccumented, the companies producing these products had no available data about the thermal properties of these materials at cryogenic temperatures. This lack of readily available information prompted these tests to determine the accuracy of using the elevated temperature data for lower temperatures also. The results of each test were written up separately as stand alone short reports for immediate use in the design stages of the V.L.P.C. cryostat cassette. Both short reports are gathered here for convenient reference.
Date: May 24, 1993
Creator: Bell, D.
Partner: UNT Libraries Government Documents Department

LHe Flow Regime/Pressure Drop for D0 Solenoid at Steady State Conditions

Description: This paper describes in a note taking format what was learned from several sources on two phase liquid helium flow regimes and pressure drops as applied to the D-Zero solenoid upgrade project. Calculations to estimate the steady state conditions for the D-Zero solenoid at 5, 10 and 15 g/s are also presented. For the lower flow rates a stratified type regime can be expected with a pressure drop less than 0.5 psi. For the higher flow rate a more homogeneous flow regime can be expected with a pressure drop between 0.4 to 1.5 psi.
Date: March 3, 1993
Creator: Rucinski, R.
Partner: UNT Libraries Government Documents Department

Chimney Open Issues

Description: In the process of developing a design for the design report, many side questions or comments arose which were not completely answered or investigated because the work was outside the scope of developing a base design. I have pored over my meeting notes and tried to list all such chimney 'open issues' in this engineering note.
Date: October 4, 1993
Creator: Rucinski, R.
Partner: UNT Libraries Government Documents Department

Cold Mass Support System for he D0 Solenoid

Description: The support system is designed to support the gravitational, magnetic, and thermal contraction loads associated with the cold mass weighing 1.46 metric tons (3210 Ibm). The loading constraints are listed in Table 1. The support system consists of axial members (axial supports) to provide longitudinal stiffness and nearly tangential members (radial supports) to provide radial stiffness. The members connect the outer support cylinder to the flat annular bulkheads of the vacuum vessel. See Figures 1 through 3 for additional details on the supports. Six axial compression-tension supports are located on the chimney end of the cryostat only. Six radial tension supports are located on each end. Both types of members are fabricated of Inconel 718 and have a design safety factor of 4 on the ultimate strength at 300 K. The axial supports are also designed for a buckling safety factor of 4 for the operating loads. Shipping stops will be installed to prevent the axial supports from going into compression during transportation. Axial and radial contraction of the coil support cylinder is accommodated by spherical bearings on both ends ofeach support member.
Date: August 9, 1993
Creator: Squires, B.
Partner: UNT Libraries Government Documents Department

Multi-Parton Light-Cone Distributions in Transversely Polarized Protons

Description: Multiparton light-cone distributions of a transversely polarized proton are identified and relations among these are discussed. The twist-four contribution to the crossection for production of Drell-Yan lepton pairs in transversely polarized p-p collisions is derived. Purely gluonic processes contributing up to the twist-three level are investigated by considering the production, also in polarized p-p collisions, of x2 mesons whose subsequent decay into a J/psi and photon reveals its initial polarization state.
Date: January 1, 1993
Creator: Hoodbhoy, Pervez
Partner: UNT Libraries Government Documents Department

Meson-Exchange Currents and the Strangeness Radius Of <sup>4</sup>He

Description: Meson-exchange current contributions to the strangeness radius of <sup>4</sup>He are computed in the one-boson exchange approximation.It is found that these contributions introduce a <(approx)10% correction to the one-body contribution.They should not, therefore, hamper the extraction of the nucleon strangeness radius from the parity-violating electron-<sup>4</sup>He asymmetry.
Date: September 1, 1993
Creator: Ramsey-Musolf, Michael & Ramsey-Musolf, Michael
Partner: UNT Libraries Government Documents Department

Chemical Relaxation Times in a Hadron Gas at Finite Temperature

Description: The relaxation time of particle numbers in hot hadronic matter with vanishing baryon number are estimated using the ideal gas approximation and taking into account resonance decays and annihilation processes as the only sources of particle number fluctuations.Near the QCD critical temperature the longest relaxation times turn out to be of the order of 10 fm and grow roughly exponentially to become of the order of 10^3 fm at temperatures around 100 MeV.As a consequence of such long relaxation times, a clear departure from chemical equilibrium must be observed in the momentum distribution of secondary particles produced in high energy nuclear collisions.
Date: July 1, 1993
Creator: Goity, Jose
Partner: UNT Libraries Government Documents Department

The heavy expansion in B decays

Description: We examine the 1/mc and 1/mb expansions in B^(*)->D^(*) processes, and point out that there are relationships among the form factors that do not receive corrections in any order of 1/mc.A different set of relationships are unchanged by (1/mc)^n corrections, while the (1/mc)^n preserved relationships are also unaffected by terms proportional to powers of Alphas(mc).All relationships are modified when terms of the form 1/(mbmc) or radiative corrections proportional to powers of Alphas(mb) are included.
Date: August 1, 1993
Creator: Roberts, Winston & Roberts, Winston
Partner: UNT Libraries Government Documents Department

Delta-Isobar magnetic form factor in QCD

Description: We consider the QCD sum rules approach for Delta-isobar magnetic form factor in the infra-red region $0<Q^2<1GeV^2$. The QCD sum rules in external variable field are used. The obtained formfactor is in agreement with quark model predictions for the Delta-isobar magnetic moment.
Date: January 1, 1993
Creator: Belyaev, Vladimir
Partner: UNT Libraries Government Documents Department

Stranger Still: Kaon Loops and Strange Quark Matrix Elements of the Nucleon

Description: Instrinsic strangeness contributions to low-energy strange quark matrix elements of the nucleon are modelled using kaon loops and meson-nucleon vertex functions taken from nucleon-nucleon and nucleon-hyperon scattering. A comparison with pion loop contributions to the nucleon electromagnetic (EM) form factors indicates the prsence of significant SU-(3)-breaking in the mean-square charge radii. As a numerical consequence, the kaon loop contribution to the mean square Sachs strangeness radius is significantly smaller than could be observed with parity-violating elastic ep experiments planned for CEBAF, while the contribution to the Sachs radius is large enough to be observed with PV electron scattering from (0+, 0) nuclei. Kaon loops generate a strange magnetic moment of the same scale as the isoscalar EM magnetic moment-a scale large enough to be observed at CEBAF-and a strange axial vecctor form factor having roughly one-third of the magnitude extracted from vp/vp elastic scattering
Date: January 1, 1993
Creator: Ramsey-Musolf, Michael & Burkardt, Matthias
Partner: UNT Libraries Government Documents Department

NN Core Interactions and Differential Cross Sections from One Gluon Exchange

Description: We derive nonstrange baryon-baryon scattering amplitudes in the nonrelativistic quark model using the "quark Born diagram" formalism. This approach describes the scattering as a single interaction, here the one-gluon-exchange (OGE) spin-spin term followed by constituent interchange, with external nonrelativistic baryon wavefunctions attached to the scattering diagrams to incorporate higher-twist wavefunction effects. The short-range repulsive core in the NN interaction has previously been attributed to this spin-spin interaction in the literature; we find that these perturbative constituent-interchange diagrams do indeed predict repulsive interactions in all I,S channels of the nucleon-nucleon sytem, and we compare our results for the equivalent short-range potentials to the core potentials found by other authors using nonperturbative methods. We also apply our perturbative techniques to the NDelta and Delta Delta systems: Some Delta Delta channels are found to have attractive core
Date: January 1, 1993
Creator: Swanson, Eric; Kovarik, M.D.; Capstick, Simon & Barnes, Ted
Partner: UNT Libraries Government Documents Department

Isoscalar Meson Exchange Currents and the Deuteron Form Factors

Description: The electromagnetic form factors for the RhoPiGamma and wSigmaGamma vertices are calculated from quark loop diagrams which take the qq structure of the Pi, Sigma, Rho, w mesons into account.The resulting form factors decrease with increasing Q<sup>2</sup> (the square of the four-momentum of the off-shell photon) considerably more rapidly than the monopole form factors obtained from vector meson dominance.The implications of this behavior, which has a significant effect on the elastic electromagnetic form factors of deuteron, is discussed.
Date: April 1, 1993
Creator: Gross, Franz & Gross, Franz
Partner: UNT Libraries Government Documents Department

Inclusive Scattering and Dynamics in Light Nuclei

Description: Inclusive scattering offers a unique opportunity to study nuclear dynamics in the regime of moderate momentum and energy transfers. We show that realistic models of nuclear interactions and current operators provide a quantitive description of the Alpha particle longitudinal and transverse responses measured in electron scattering. A consistend picture of in-medium nucleon dynamics naturally emerges from an analysis of these (e, e') data and quasi-elastic data from hadronic reactions on heavier nuclei. Its essential features are : (1) a significant quenching of the longitudinal strength; (2) a substantial enhancement of the transverse strength due to the two-nucleon currents required by gauge invariance; and (3) a large shift to higher energies of the isovector strength as observed in the charge-exchange response to hadronic probes. Within this theoretical framework the interactions and currents due to pion exchange play an absolutely crucial role.
Date: May 1, 1993
Creator: Schiavilla, Rocco
Partner: UNT Libraries Government Documents Department

Measurement of the Inclusive B-Lifetime Using $\rm {J/\psi}$'s at the CDF Experiment

Description: This dissertation describes the measurement of the average B hadron lifetime using a high statistics sample of B → J/ΨX decays produced in p$\bar{p}$ collisions at a center of mass energy of √s = 1.8 TeV at the Fermilab Tevatron. The integrated luminosity of the sample is 10.1 pb<sup>-1</sup> recorded with the Collider Detector at Fermilab (CDF). In this analysis the decay vertex of the decay J/Ψ → μ<sup>+</sup>μ<sup>-</sup> as reconstructed by a silicon vertex detector is used to extract the lifetime from the data. This measurement is the average over all b-hadrons produced weighted by the product of their branching ratios into J/Ψ and their production cross sections. We find the following value for the average b hadron lifetime: τ<sub>B</sub> = 1.46 ± 0.06(stat.) ± 0.06(syst.) ps. This is the first measurement of the b-hadron lifetime at a hadron collider. It demonstrates that it is possible to access the large b-quark production cross section in p$\bar{p}$ collisions and to achieve high statistics even in modes which have small product branching ratios as in this case: BR(B → J/ΨX) • BR(J/Ψ → μ<sup>+</sup>μ<sup>-</sup>) = 7.7 x 10<sup>-4</sup>.
Date: August 1, 1993
Creator: Wenzel, Hans-Joachim
Partner: UNT Libraries Government Documents Department

D0 Solenoid Upgrade Project: D0 Solenoid Current Leads

Description: This engineering note documents information gathered and design decisions made regarding the vapor cooled current leads for the D-Zero Solenoid. The decision was made during design group meetings that the D-Zero Solenoid, rated at 4825 amps, should use vapor cooled current leads rated at 6000 amps. CDF uses 6000 amp leads from American Magnetics Inc. (AMI) and has two spares in their storage lockers. Because of the spares situation and AMI's reputation, AMI would be the natural choice of vendor. The manufacturer's listed helium consumption is 19.2 liters/hr. From experience with these types of leads, more stable operation is acheived at an increased gas flow. See attached E-Mail message from RLS. We have decided to list the design flow rate at 28.8 liquid liters/hr in the design report. This corresponds to COFs operating point. A question was raised regarding how long the current leads could last at full current should the vapor cooling flow was stopped. This issue was discussed with Scott Smith from AMI. We do not feel that there is a problem for this failure scenario.
Date: October 4, 1993
Creator: Rucinski, R.
Partner: UNT Libraries Government Documents Department

D0 Solenoid Upgrade Project: Heat Load Calculations for the Solenoid Chimney

Description: This engineering note documents the calculations done to determine the chimney heat loads. These heat load numbers were reported in the D0 solenoid upgrade design report. The heat loads to the LN2 circuit were done by Andrew Stefanik, RDIMechanical Systems group. They were part of his LN2 shield calculations dated 2/23/93. Pages 1 thru 3 of his calculations that apply to the chimney are attached. The heat loads to the LHe circuit were done originally on 12/16/92 and then revised on 12/23/92 to be more conservative. The raw calculations are attached. I include both the original 12/16 version and the 12/23 revised version to document the amount of conservativeness added.
Date: May 26, 1993
Creator: Rucinski, R.
Partner: UNT Libraries Government Documents Department

D0 Solenoid Upgrade Project: Pressure Ratings for Some Chimney and Control Dewar Componenets

Description: Pressure rating calculations were done for some of the chimney and control dewar components. This engineering note documents these calculations. The table below summarizes the components looked at, and what pressure rating are. The raw engineering calculations for each of the components is given.
Date: May 25, 1993
Creator: Rucinski, R.
Partner: UNT Libraries Government Documents Department

D0 Solenoid Upgrade Project: Rectangular Liquid Helium Tube, Miscellaneous Information

Description: This engineering note contains miscellaneous information about the rectangular liquid helium supply tube for the D-Zero solenoid. The information is fairly superficial, but could be used as a starting point for a future engineer who is going to specify and puchase the tubing. The chimney contains 4 conductors attached to an aluminum liquid helium supply tube. Because good thermal contact is desired, the tube will have flat sides. Aluminum is chosen to match the thermal contraction coefficient of the superconductor's aluminum stabilizer. The type of aluminum is chosen as 6061-T6 because it's allowable stress in ANSI/ASME B31.3 is higher than for other alloys. A different alloy could be chosen for extrusion reasons. The highest pressures this tubing should see will be during a quench. Current calculations predict the peak pressure during a quench to be 520 psi a for one-way relieving and 250 psia for two way relieving. Whatever the final alloy selection, the tubing needs to have a high enough allowable working pressure. There is very little room in the obround section of the chimney. In that portion the shape is rectangular, 12.7 mm (0.50-inch) x 31.8 mm (1.25-inch). A drawing shows the flow path cross section. This also could be changed for extrusion reasons if necessary. The important thing here is to estimate the pressure drop and make sure it is acceptable. Pressure drop estimates for this cross section are acceptable since it only about 10 feet in length.
Date: May 26, 1993
Creator: Rucinski, R.
Partner: UNT Libraries Government Documents Department

D0 Solenoid Upgrade Project: Thermal Contraction Analysis for the D0 Solenoid Chimney

Description: This engineering note documents the thermal contraction analysis that was done for the D-Zero solenoid chimney. The analysis was done as support of the 'Design Report of the 2 Tesla Superconducting Solenoid for the Fermilab DO Detector upgrade.' The cryogenic LHE and LN2 lines were analyzed for combined pressure, thermal movement, and dead weight. The tubing was stress analyzed per ASME code for Pressure Piping, standard ANSI AS:ME B31.3, for eight combinations ofthermal loading. A commercial pipe stress analysis and design system by Algor{reg_sign} was used for the analysis. Stresses calculated were well below allowables. Based on the analysis, the cryogenic lines will be installed at an offset from the vacuum jacket centerline so that during steady state cold operation, the cryogenic lines will be in a proper location.
Date: September 30, 1993
Creator: Rucinski, R.
Partner: UNT Libraries Government Documents Department

D0 Solenoid Upgrade Project: Vacuum Pumping Calculations for the D0 Solenoid

Description: This engineering note documents the calculations done to determine the vacuum pumping speed for the D-Zero solenoid. The raw calculations are attached. A summary of the results are listed. The vacuum pumping speed of the solenoid is determined by the conductance of the pumping path. At higher pressure ranges during initial pumpdown, the conductances will be rather high. Calculations were not done for the transient pumpdown period, only the steady state type pumping situation. The pressure is assumed to be on the order of 10E-7 torr. This is the free molecular flow regime based on Knudsen number. This pressure regime is also where the pumping speed would be least. The conductances were calculated based on pumping helium gas at a temperature of 300 Kelvin. The total conductance of the pumping path from the solenoid to the inlet of the turbomolecular pump is 11.8 L/s. The effective pumping speed of a 1000 L/s turbo pump attached to this pumping path is 11.7 L/s. The minimum required pumping speed for design purposes was set at 4.3 L/s. This value was arrived at by assuming a warm leak size (10E-8 atm-cc/sec) was not detected during fabrication of the solenoid. It is then assumed that the leak leaks cold liquid helium into the vacuum space. With this leak rate, a 4.3 L/s pumping speed would be able to maintain a 2 x 10E-7 torr pressure in the solenoid vacuum jacket. The solenoid would be able to be operated with this small leak with continuous pumping.
Date: August 2, 1993
Creator: Rucinski, R.
Partner: UNT Libraries Government Documents Department

Control Dewar Open Issues

Description: In the process of developing a design for the design report, side questions or comments arose which were not completely answered or investigated because the work was outside the scope of developing a base design. I have pored over my meeting notes and tried to list all such control dewar 'open issues' in this engineering note.
Date: October 4, 1993
Creator: Rucinski, R.
Partner: UNT Libraries Government Documents Department

Control Dewar Secondary Vacuum Container

Description: This engineering note provides background information regarding the control dewar secondary vacuum container. The secondary vacuum container has it's origin with the CDP control dewar design. The name secondary vacuum container replaced the CDP term 'Watt can' which was named after Bob Watt (SLAC), a PAC/DOE review committee member who participated in a review of CDP and recommended a secondary vacuum enclosure. One of the most fragile parts of the control dewar design is the ceramic electrical feed throughs located in the secondary vacuum container. The secondary vacuum container is provided to guard against potential leaks in these ceramic insulating feed throughs. The secondary vacuum container has a pumping line separate from the main solenoid/control dewar insulating vacuum. This pumping line is connected to the inlet of the turbo pump for initial pumpdown. Under normal operation the container is isolated. Should a feedthrough develop a small leak, alternate pumping arrangements for the secondary vacuum container could be arranged. The pressure in the secondary vacuum container should be kept in a range that the breakdown voltage is kept at a maximum. The breakdown voltage is known to be a function of pressure and is described by a Paschen curve. I cannot find a copy of the curve at this time, but from what I remember, the breakdown voltage is a minimum somewhere around 10-3 torr. Ideally the pressure in the secondary vacuum can should be kept very low, around 10 E-6 or 10 E-7 torr for maximum breakdown voltage. If however a leak developed and this was not possible, then one could operate at a pressure higher than the minima point.
Date: October 4, 1993
Creator: Rucinski, R.
Partner: UNT Libraries Government Documents Department

Control Dewar Subcooler Heat Exchanger Calculations

Description: The calculations done to size the control dewar subcooler were done to obtain a sufficient subcooler size based on some conservative assumptions. The final subcooler design proposed in the design report will work even better because (1) It has more tubing length, and (2) will have already subcooled liquid at the inlet due to the transfer line design. The subcooler design described in the 'Design Report of the 2 Tesla Superconducting Solenoid for the Fermilab D0 Detector Upgrade' is the final design proposed. A short description of this design follows. The subcooler is constructed of 0.50-inch OD copper tubing with 1.0-inch diameter fins. It has ten and one half spirals at a 11.375-inch centerline diameter to provide 31 feet of tubing length. The liquid helium supply for the solenoid flows through the subcooler and then is expanded through a J-T valve. The subcooler spirals are immersed in the return two phase helium process stream. The return stream is directed over the finned tubing by an annulus created by a 10-inch pipe inside a 12-inch pipe. The transfer line from the refrigerator to the control dewar is constructed such that the liquid helium supply tube is in the refrigerator return stream, thereby subcooling the liquid up to the point where the u-tubes connect the transfer line to the control dewar. The subcooler within the control dewar will remove the heat picked up in the helium supply u-tube/bayonets. The attached subcooler/heat exchanger calculations were done neglecting any subcooling in the transfer line. All heat picked up in the transfer line from the refrigerator storage dewar to the control dewar is absorbed by the supply stream. The subcooler was sized such that the two phase supply fluid is subcooled at 1.7 atm pressure and when expanded through a JT valve to 1.45 atm ...
Date: October 4, 1993
Creator: Rucinski, R.
Partner: UNT Libraries Government Documents Department