D-0 South End Cap Calorimeter Cold Test Results

The South endcap calorimeter vessel was moved into Lab A on Sept. 18, 1990. A cooldown of the pressure vessel with liquid nitrogen was performed on Sept. 26 to check the vessel's integrity. With the pressure vessel cold, the insulating vacuum was monitored for leaks. Through out the testing, the insulating vacuum remained good and the vessel passed the test. The cold test was carried out per the procedures of D-Zero engineering note 3740.220-EN-250. The test was very similar to the cold test performed on the Central Calorimeter in October of 1987. The test of the ECS was performed in the same manner using the same equipment as the ECN cold test. Reference D-Zero engineering notes 3740.210-EN-122, 3740.000-EN-I07, and 3740.210-EN-II0 for information about the CC cold test. Reference EN-260 for the results of the ECN cold test. The insulating vacuum space was pumped on while equipment was being connected to the pressure vessel. Two hours after starting to pump with the blower the vacuum space pressure was at about 40 microns. The pumping continued overnight (another 16 hours). In the morning the pressure was 11.5 microns. A rate of rise test was performed. With the pump valved off, the pressure rose to 14 microns within 5 minutes and then rose to 16 microns in 6 hours (0.33 microns/hour). After all connections were made to the pressure vessel, a vacuum pump with an estimated effective pumping speed of about 70 scfm was valved on. After 18 hours, the pressure vessel was down to 270 microns. An additional day of pumping took the pressure down to only 250 microns. A leak was then found and fixed around the seal of the rupture disc. The pump was put on line again. The pressure vessel with pump on line was 27 microns after 16.5 hours. A rate of rise was then conducted. The pressure was 90 microns after valving out the pump. After 30 minutes the pressure increased to 107 microns. (34 microns/hr)

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

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

Lead Thickness Measurements

The preshower lead thickness applied to the outside of D-Zero's superconducting solenoid vacuum shell was measured at the time of application. This engineering documents those thickness measurements. The lead was ordered in sheets 0.09375-inch and 0.0625-inch thick. The tolerance on thickness was specified to be +/- 0.003-inch. The sheets all were within that thickness tolerance. The nomenclature for each sheet was designated 1T, 1B, 2T, 2B where the numeral designates it's location in the wrap and 'T' or 'B' is short for 'top' or 'bottom' half of the solenoid. Micrometer measurements were taken at six locations around the perimeter of each sheet. The width,length, and weight of each piece was then measured. Using an assumed pure lead density of 0.40974 lb/in{sup 3}, an average sheet thickness was calculated and compared to the perimeter thickness measurements. In every case, the calculated average thickness was a few mils thinner than the perimeter measurements. The ratio was constant, 0.98. This discrepancy is likely due to the assumed pure lead density. It is not felt that the perimeter is thicker than the center regions. The data suggests that the physical thickness of the sheets is uniform to +/- 0.0015-inch

D-Zero Central Calorimeter Pressure Vessel and Vacuum Vessel Safety Notes

The relief valve and relief piping capacity was calculated to be 908 sefm air. This exceeds all relieving conditions. The vessel also has a rupture disc with a 2640 scfm air stamped capacity. In order to significantly decrease the amount of time required to fill the cryostats, it is desired to raise the setpoint of the 'operating' relief valve on the argon storage dewar to 20 psig from its existing 16 psig setting. This additional pressure increases the flow to the cryostats and will overwhelm the relief capacity if the temperature of the modules within these vessels is warm enough. Using some conservative assumptions and simple calculations within this note, the maximum average temperature that the modules within each cryostat can be at prior to filling from the storage dewar with liquid argon is at least 290 K. The average temperature of the module mass for any of the three cryostats can be as high as 290 K prior to filling that particular cryostat. This should not be confused with the average temperature of a single type or location which is useful in protecting the modules-not necessarily the vessel itself. A few modules of each type and at different elevations should be used in an average which would account for the different weights of each module. Note that at 290 K, the actual flow of argon through the relief valve and the rupture disk was under the maximum theoretical flows for each relief device. This means that the bulk temperature could actually have been raised to flow argon through the reliefs at their maximum capacity. Therefore, the temperature of 290 K is a conservative value for the calculated flow rate of 12.3 gpm. Safeguards in addition to and used in conjunction with operating procedures shall be implemented in such a way so that the above temperature limitation is not exceeded and such that it is exclusive of the programmable logic controller (PLC). One suggestion is using a toggle switch for each cryostat mounted in the PLC I/O box which would maintain control of the signals to open the cold fill valves of each cryostat. With the safeguards in place while carefully monitoring the temperatures during a cooldown cycle in each cryostat, the set pressure in the argon storage dewar can safely be increased to 20 psig

Search for Variable Stars in the Globular Cluster M3

We describe here results of a photometric time-sequence survey of the globular cluster M3 (NGC 5272), in a search for contact and detached eclipsing binary stars. We have discovered only one likely eclipsing binary and one SX Phe type star in spite of monitoring 4077 stars with $V<20.0$ and observing 25 blue stragglers. The newly identified SX Phe star, V237, shows a light curve with a variable amplitude. Variable V238 shows variability either with a period of 0.49 d or with a period of 0.25 d. On the cluster colour-magnitude diagram, the variable occupies a position a few hundredths of magnitude to the blue of the base of the red giant branch. V238 is a likely descendent of a binary blue straggler. As a side result we obtained high quality data for 42 of the previously known RR Lyrae variables, including 33 of Bailey type ab, 7 type c and 2 double-mode pulsators. We used equations that relate the physical properties of RRc stars to their pulsation periods and Fourier parameters to derive masses, luminosities, temperatures and helium parameters for five of the RRc stars. One of the RRd stars (V79) has switched modes. In previous studies, it was classified as RRab, but our observations show that it is an RRd star with the first overtone mode dominating. This indicates blueward evolution on the horizontal branch.Comment: 21 pages including 14 figures, Latex, requires mn.sty, psfig.sty. Submitted, MNRA

D0 Solenoid Upgrade Project: Solenoid Insulatiing Vacuum Vessels; Relief Path Capacity Calculation

This engineering note documents the calculations done to determine the relief capacity of the solenoid vacuum pumping line. The calculations were done by David Bell, a co-op student from the University of Wisconsin. The calculations are attached. The conclusion is that the vacuum pumping line has a venting capacity of 129 g/s warm helium or 298 g/s warm nitrogen. Both of these capacities are much larger than the expected operating mass flow rates of the liquid helium (5 to 15 g/s) or liquid nitrogen (2 or 3 g/s) circuits. The calculations assume the solenoid vacuum vessel is at 3 psig and the relief plate is set at 1.5 psig. Additional calculations were done to prove that the venting capacity of the vacuum pumping line exceeded flowrates due to a failure mode. These calculations are attached. Since the system is not finalized, (pipe sizes not determined, components sized...) the calculations were done by first picking reasonable line sizes based on known allowed pressure drops in the system and then doing a maximum delivery rate calculation if a line was completely severed in the vacuum space of the solenoid/control dewar. The numbers from these calculations say that failure mode flow rates are 80 g/s liquid helium or 80 g/s liquid nitrogen. Both these values are less than the capacity of the relief line. In the five months since the (12/92 Dave Bell) calculations were done, some changes occured to the relief path. The most notable is that the radiation shield is now considered to be 6.625-inch O.D. instead of 6.00-inch used in the venting calculation. This change would tend to lower the capacity numbers. Another change was that for about half the venting path the chimney vacuum shell size was increased to 10-inch pipe. This change tends to increase the capacity numbers which were done assuming 8-inch pipe. These changes taken together probably offset each other or make the capacity numbers better. In either case, since the margin of safety is large, the calculations have not been redone

A BVRcIc Survey of W Ursae Majoris Binaries

We report on a BVRcIc survey of field W Ursae Majoris binary stars and present accurate colors for 606 systems that have been observed on at least three photometric nights from a robotic observatory in southern Arizona. Comparison with earlier photometry for a subset of the systems shows good agreement. We investigate two independent methods of determining the interstellar reddening, although both have limitations that can render them less effective than desired. A subset of 101 systems shows good agreement between the two reddening methods.Comment: 10 pages, 6 figures, accepted for publication in A

Radial Velocity Studies of Close Binary Stars.XIII

Radial-velocity measurements and sine-curve fits to the orbital radial velocity variations are presented for ten close binary systems: EG Cep,V1191 Cyg, V1003 Her, BD+7_3142, V357 Peg, V407 Peg, V1123 Tau, V1128 Tau, HH UMa, and PY Vir. While most of the studied eclipsing systems are contact binaries, EG Cep is a detached or a semi-detached double-lined binary and V1003 Her is a close binary of an uncertain type seen at a very low inclination angle. We discovered two previously unknown triple systems, BD+7_3142 and PY Vir, both with late spectral-type (K2V) binaries. Of interest is the low-mass ratio (q = 0.106) close binary V1191 Cyg showing an extremely fast period increase; the system has a very short period for its spectral type and shows a W-type light curve, a feature rather unexpected for such a low mass-ratio system.Comment: Accepted by AJ. 19 pages including 5 figure

W UMa-type Binary Stars in Globular Clusters

A sample of 86 contact binary systems in 14 globular clusters with available color index data in (B-V) or in (V-I) has been analyzed. At least one third of all systems are numerous foreground Galactic Disk projections over long lines of sight to the clusters. Since the selection of the cluster members has been based on the MV(logP, color) calibrations, the matter of a metallicity-correction required particular attention with the result that such a correction is apparently not needed at the present level of accuracy. Analysis of the color-magnitude and period-color relations shows that globular cluster members are under-luminous relative to the Galactic Disk contact systems mainly because of the smaller sizes and, consequently, shorter orbital periods; the color-index effect of the diminished blanketing is less important, especially for (V-I). The variability amplitudes for the Blue Straggler systems show a significantly different distribution from that for systems below the Turn Off Point (TOP): The BS systems show only small amplitudes while the distribution for the systems below the TOP is peculiar in containing only large amplitude systems. This difference is linked to an observational selection effect so that efforts at determining the frequency of occurrence of the contact systems below the TOP have been judged to be premature; the frequency among the BS stars could be at about 45+-10 BS stars per one contact BS binary.Comment: submitted for publication in Astronomical Journal; 8 figures, 3 tables (Table 1 in landscape