This page will contain the minutes of TUNL's weekly meeting. Scroll down or click on the date to view the minutes for the meeting you are interested in.
September 4, 1999 -- Discussions with Kengo Nakamura on the gain testing, mounting, and sealing of 20 inch PMT's.
September 11, 1999 -- Discussion of tests on the portable MCA system being developed for use in Sendai. There was also discussions on the GEANT simulations for the outer detector and for the water tank.
February 3, 2000 -- Discussion of mountings and installation for PMTs
February 10, 2000 -- Discussion of electronics issues from Giorgio's email, bottom Tyvek partition, and magnetic fields around the outer detector PMTs
February 17, 2000 -- Discussion of manpower issues and cabling of OD PMTs, plus other important miscellaneous items.
February 24, 2000 -- Discussion of cable splicing issues.
March 2, 2000 -- Discussion of new splicing technique for OD PMTs, timetable for travel, and epoxy testing.
March 9, 2000 -- Discussion of Tyvek and cable ordering.
March 16, 2000 -- Discussion of splicing, cable routing, and cable orders.
March 23, 2000 -- Discussion of sealants, tyvek testing, ID PMT installation, power supplies, and splicing issues.
March 30, 2000 -- Discussion of water creep and effectiveness of BNC splicing technique.
April 6, 2000 -- Discussion of different splicing techniques and pressure test for water creep in regular cable.
April 13, 2000 -- Discussion of splicing components, travel to Sendai, and results of weeklong pressure test.
April 15, 2000 -- Discussion of the pressure test with Kengo, mounting and Mitsui design, Kamiokande mount modifications, and PMT assembly process.
April 18, 2000 -- Discussion of travel dates, new design for cable routing, and calibration of PMTs at Kamioka.
April 27, 2000 -- Discussion of Mitsui design modification, Tyvek installation, and the application of the chimney veto.
May 4, 2000 -- Discussion of Berkeley meeting and calibration of outer detector.
May 11, 2000 -- Discussion of Berkeley meeting and materials for assembling OD PMTs in Sendai.
May 18, 2000 -- Discussion of cables and connectors.
September 4 KamLAND Meeting Notes --------------------------------- Present: Chris, Hoe, Hugon, Jason, Kengo, Ludwig, Michael, Werner Kengo discusses electronics (three types: LBL, Oak Ridge, KEK) - Old Kamiokande electronics can be used for OD. - Final decision on electronics should be made in Hawaii. Kengo discusses phototubes - 240 needed for OD and 600 requested for ID. - 200 8" tubes also needed? - 842 existing 20" tubes which passed the dark current signal check (842 survived out of ~1000). - There are 50 additional unchecked tubes (assume ~40 work). - Still uncertain how tubes will operate in oil. Kengo discusses gain testing of phototubes - Gain testing must be completed by January 2000 in order to know how many new tubes to order from Hamamatsu. - Assume that more time required to set up the gain test apparatus than to actually test the tubes. - 8 to 10 tubes can be tested at once in the black room, using a 17" tube as a reference to monitor shift-to-shift changes. - Kengo proposes using a laser and optical fibers to uniformly illuminate the tubes. Hugon suggests possibility of using LEDs instead. Werner and Hugon will look into setting up 8 to 10 LEDs as a backup plan, and the next TUNL person to travel to Sendai can take this LED setup with them. - Instead of Kengo's design (involving ADC and CAMAC), Hugon proposes using a system involving a PreAMP, an AMP and a MCA (Hugon and Werner will investigate this). This setup would be much cheaper. It will not provide us with timing aspect of tubes, but will adequately test gain (gain vs. HV). - Kengo needs to buy a computer and transformer in Japan. TUNL will ship the PreAMP/AMP/MCA setup (with mini-NIM bin) to Sendai along with the computer card for the MCA. - Single photoelectron test will not be done now, but can be later (20" tubes cannot see single photoelectron peak). Discussion of tube mounting - Use ~5mm diameter stainless steel cables which will be anchored to the floor and hung from the catwalk. - It must be determined soon where exactly to drill holes in floor before any construction is started. - Each tube is ~15 kg dry weight down, ~60 kg wet weight up, so cables must be able to support this. - Question of drilling holes in existing L-beams of wall mounts. - Some sort of clamp design (clamping the mount to the suspended cables) will be used to position the wall-mounted tubes at the appropriate heights. - Discussion of mounting for floor PMTs. Use weights to counter the 60kg upward force of the tubes in water? Discussion of water sealing of the phototubes - If glue is used, it must be soft, to accomodate temperature and expansion changes. Hard glue is likely to fail. - Hugon suggests an O-ring setup to seal the tube. He will look into this in more detail, as will Kengo. - Failure rate of old tubes is discussed. If a sealed tube is placed in water and remains in water, failure rate is low. If a sealed tube is placed in water, removed and placed back into water at a later time, failure rate is high. Scheduling is discussed - Diane and Jason will go to Sendai in early October. - Hugon, Jason and Chris can go in December, if needed. Back to top
September 11 KamLAND Meeting Notes ---------------------------------- Present: Chris, Hoe, Jason, Michael, Ryan Jason discusses hardware - MCA system (with Amp and PreAmp) is up and running. - Relative gain vs. HV has been measured for one tube, exponential behavior. - Gain will be calibrated later. - Pulser/LED operates at 10kHz and we have, as expected, poor resolution (~60%). Concerns, questions, and things to do - Chris discussed possibility of purchasing a NANO-LED pulser (~$3000 for one) as recommended by EEng dept. It can go down to 50ps, which would be good for timing resolution. - We will need to compare noise vs. (noise + signal) to see if we are able to see single photoelectrons. - We already have a portable system for testing the gain (LED and MCA) for one phototube, but how do we scale it to eight or ten tubes? - Jason will look into fiber-optic cables (max. length = 3m). - Three old Kamioka tubes have been delivered, and Hugon has taken two over to UNC to investigate sealing against water leaks. Ryan discusses M.C. simulations - He is detecting approximately three times as many photoelectrons in his code as compared to Yuri's (Oak Ridge) code...why? - Quantum efficiency = 1/4. - Collection efficiency = 1/2. - Reflection of the top = 3/4. - Geometrical efficiency for detecting light before it is absorbed is ~1/6. - Ryan will run some test cases like Yuri's code to see if he can determine where the factor of 3 difference in # of photoelectrons is coming from. - Hoe will continue working on the water tank code. Trip to Hawaii - At least Chris, Ryan and Ludwig are going (Hugon too?). Back to top
February 3 KamLAND Meeting Notes -------------------------------- Present: Ludwig, Chris, Werner, Jason, Hugon, Diane, Hoe, Michael Discussion of Kengo's January 27, '00 email - Focused on mounting structures, cost estimation, and other topics. - Email was accompanied by several technical drawings provided by Mitsui (outlining location of side, top and bottom PMTs). - Several drawings by hand by Kengo indicating preliminary mounting ideas for PMTs. Mountings (General) - The old Kamiokande supports can be used, but add-ons will have to be designed and made (by us?) using a configuration of L-beams. - It is unclear whether these add-ons would be welded to the existing mounting (Kamiokande) or whether they could be bolted on. - The TUNL consensus was that it would be best to bolt, but Mitsui has expressed that they would prefer welding (more costly?). Mountings (Floor) - Kengo's design involves adding two U-shaped structures (made of L-beams) to the existing mountings (to form a cube). - TUNL believes this is overkill, and will offer alternatives. - To situate these tubes on the floor, 20 I-beams (or C-beams) would be laid radially on the floor from the center and the PMT mountings would be either bolted or welded to these beams. - It is unclear in the drawings if these 20 floor beams would be attached to existing sphere support beams or if they would be heavy enough alone to counteract the buoyancy of the PMTs. Mountings (Top) - We would like to change the PMT layout to accomodate the 30 beam structure. We propose using a 30-15-15 configuaration at 8m-6m-4m. - Initial ideas for the top PMT mountings are similar to the bottom mounting ideas. Designs and Drawings - TUNL is unclear as to who is in charge of designing the mountings. - We would like Mitsui to provide detailed drawings. - Are extra mountings to be added in Sendai or after shipping to Kamioka? Tyvek Placements - Tyvek is preferred since aluminized Mylar is said to have some sort of coating. - Tyvek would be used only on the top the surface of the sphere. We have decided to eliminate the bottom partition. - There is uncertainty as to who will be installing the Tyvek. Cabling and Power Supplies - Power supply standard for the PMTs should be the same as the ID to avoid having two different standards. - RG-58 is not rated high enough for the HV load we will use (1500-2300 V), so it has been proposed to use RG-59 instead. - Werner is looking into the cost of purchasing cable in U.S. vs Japan, and cost of shipping cables from U.S. to Sendai. - We can then decide whether to add connectors here or in Sendai. Kengo is meeting with Mitsui tomorrow (February 4), so we need to contact him before that meeting. So Jason will work on some drawings and Ludwig will work on the email message. Back to top
February 10 KamLAND Meeting Notes --------------------------------- Present: Ludwig, Werner, Hugon, Ryan, Diane, Jason, Hoe, Michael Giorgio from the Stanford group has requested the following information: 1. What is the length of the veto PMT cable? 2. Where is the veto electronics located? 3. What is the trigger rate due to radioactivity from the rock? 4. What is the length of the trigger gate? (100ns?, 200ns?) 5. What is being considered for the chimney veto? 6. For the front-end trigger, will using the response from 15PMTs be a problem for the O.D.? (this is the current plan for the I.D.) Responses to questions 1 and 2 - PMT cable length is still unresolved as we do not know the location of the pre-electronics bin. It should be located near the inner detector bin, but no official decision has been made. - HV cables will need to be longer than signal cables because the HV distributors will be located in an access tunnel instead of above the detectors. - Due to timing, the outer and inner detector PMTs must have the same lengths. Because of the placement of the PMTs, this distance will be dependent on the outer detector. Response to question 3 - Radioactivity will be uncorrelated, single events and because the PMTs will be binned, this background will be very negligible. - Therefore, the trigger rate will be essentially zero and the radioactivity will only slightly add to the dark current Response to question 4 - Ryan stated that it will take a muon ~100 ns to traverse the outer detector from top to bottom, and an uncertainty of 20 ns for the photon to convert to a pulse inside the PMT. - Timing is also voltage dependent and the HV for any given PMT will vary between 1500 and 2300 volts. - Therefore, we believe that the trigger gate length should conservatively be set at 200 ns Response to question 5 - Based on a previous meeting with Suzuki-san, we contend that the chimney veto is not TUNL's responsibility. - However, the plan put forth by the Research Center for Neutrino Science uses 24 eight inch PMTs, all facing up towards the ceiling. - 8 PMTs will be inside the acrylic plate and 8 will be located outside the plate. All 16 are within the sphere and are located in buffer oil. - The remaining 8 PMTs' positioning could not be determined from the drawings or accompanying descriptions Response to question 6 - We need to know how LBL is going to set up the electronics before we can answer with any more detail - We can bin the PMTs, but it is unclear as to what information will be carried in these bins: - analog/digital - fire/not fired - info on the number of PMTs per bin that fired Tyvek Partitioning - Kengo inquired about the bottom Tyvek partition, showing interest in keeping a partition. - It was decided that due to the low occurence of events coming up from the bottom and the fact that the sphere will be covered in Tyvek, the bottom partition is not needed. Magnetic field coils close to outer detector PMTs - The compensating magnetic field coils will be located very near to the outer detector PMTs - We will want to perform some tests to confirm that the mu-metal shielding will effectively eliminate the magnetic field inside the shield. Back to top
February 17 -- KamLAND meeting notes ------------------------------------ Present: Chris, Ludwig, Werner, Diane, Hugon, Ryan, Jason, Hoe, Neal, and Michael Questions of radioactivity - Ryan will reconsider this problem accounting for water-proofing paint on walls (which would help stop even more electrons), but analysis should not change. - Ludwig asked Suzuki what Kamiokande triggered on (dark current /radioactivity / etc) but he has not received a response from Suzuki. Chimney Veto - Ludwig has asked Suzuki to clarify who is responsible for the chimney veto, but he has not received a response back. Discussion regarding cables and electronics: - ID cables come up through one of two "spigots" (N & S), or access holes located near the chimney. For ID tubes, 40 m of cable gets them to the spigot. From spigots, cable trays will carry the add-on cables to get the cables to the electronics "hut". BNC connectors will be used at spigots instead of a patch panel. - OD cables need to be brought to the ID spigots, whereupon LBL will take care of the rest of the wiring. Currently, the OD cables must reach the spigots within 40 meters. - Clean room will be located above chimney area (to prevent radon contamination in scintillator) and we will need to provide cable trays to get the OD cables to the clean room. - OD signal cables will be made from RG-58, though we need to check to make sure this is the same as will be used by ID tube cables. - TUNL is responsible for getting the HV cables (RG-59) to "Stage 1" location. Length for HV cables is not a concern. We may be able to use existing tray tables but may have to provide our own. - Cable casing needs to be PolyEthlyene (due to water), and we need to double-check that RG-58 and RG-59 have PE casing. - Our current design has 235 OD PMTs in all (60 ceiling, 120 side, 55 floor) This is to be the final number - we will not need to upgrade to a larger number in the future. Gating of OD PMTs - Is it a logical gate (or else what type?) - Will it contain info on how many tubes fired and which ones? - We have determined that the trigger gate should be set at 200 ns. Discussion of TUNL manpower (both Sendai and Kamioka) - Two months of help has been requested by Bob Svoboda for ID tube installation in May and June. This means sending two groups of two people to Kamioka for about three weeks. - Diane and Jason will be working in Sendai during April and May and will not be available for ID tube installation. - Neal (Duke engineering student) and Michael are definitely available. Hugon claims there is a UNC grad student interested in joining the collaboration. Plus, Chris has NCSU student, Mic, who should be able to go. That gives Neal, Michael, Mic, and UNC student, which means we can send two groups of two people for three weeks to help with ID tube installation. - Neal is free from May 1 - June 16 (or after June 17). Michael is free from May 1 - May 22 and after June 10. UNC student would not be free to go until after May 20. Jason will write Mic to find out when he can go. - Ludwig proposes that Neal and Michael go together and the other two go together, with a few days of overlap between the two two-man teams. - Hugon should be free to go after the second week in May. Werner would like to go for two weeks at some point. Ludwig is going for 8 months to Sendai/Kamioka beginning October 1. - Unclear when Kengo will be ready for Jason and Diane in Sendai - depends on whether we can use the 17"-tube setup. Diane needs to go early and come back by mid May. Jason is free after April 8 - May 25. Ludwig can go to Sendai in May after Duke classes (ending ~May 10). Housing - Berkeley has 4 appartments near Kamioka, but can TUNL put people there? We will have to ask Bob Svoboda. - Talked about renting an appartment in Sendai but we're not sure if 1-year lease is possible. It may be more reasonable to stay in hotel. Sealing of PMTs - Kengo is presumably still working on the sealing of the tubes (Tor-seal?). We haven't heard an update from him. PMT cleaning - Mitsui will be cleaning the tubes, but at what price??? Cable lengths - Cables will be cut and connectors attached here at TUNL. - We'll test cable sealing (shrinkwrap-type material) here but we must devise a way to get cable lengths consistent to about 2 cm. A jig will be designed to insure this length. Back to top
February 24 -- KamLAND meeting notes ------------------------------------ Present: Ludwig, Werner, Diane, Hugon, Jason, Neal, Hoe and Michael ID cable splicing plan - Using RG-303 cable (expensive teflon-coated RG-58). - Using small circuit board for splicing (dimensions: 46mm x 23mm). Width is so large because they are splicing both HV and signal together and there needs to be at least 7mm spacing between ground line and the HV pad on the board. - Board makes 50-Ohm resistor easy to solder (but what about the shielding do we solder or crimp?) OD cable splicing plan - Jason and Diane are proposing using similar circuit board for OD splicing - Dimensions would be no larger than 46mm x 11mm, as we must shrink-wrap tubing over it. - Tennessee would be willing to make the boards for us, though we should make the design for the board. Neal will look into designing a smaller board for them to make for us. - How do we best attach the shielding to the board? Neal thinks soldering is more reliable, Hugon thinks maybe crimping is better. Must decide what is best for mass production (~300 tubes). - Uncertainty as to whether we actually need to include the 50-Ohm resistor when splicing the cable. It seems to depend on whether the AMP is set to 50-Ohm termination (internal). So we must talk to Suekane to check on the amplifier design. - Ludwig claims that the electronics are built primarily for the ID tubes (new tubes already have 50-Ohm impedance), so it seems that we should indeed include the 50-Ohm resistor on the OD tubes. - For HV cables, we will NOT use a circuit board. Shrink-wrap concerns and waterproofing of cables - Shrink-wrap ratio is typically 2-to-1, so the circuit board needs to be smaller than 11mm wide, as cable is approximately 5mm wide. - Will we want to include a gel inside of the shrink-wrap to increase stability of crimp/solder jobs? It will be messy, and what is the best way to accomplish it? - For starters, Neal will talk to RayChem among others about shrink-wrap tubing and kits. He will look into making some test boards with shrink-wrap. The existing splice jobs from the SuperK tubes have shrink-wrap, but we don't know if they used an epoxy between the cable and shrink tubing. - While we will be using polyethylene(PE)-coated RG-58, and it seems that we would be smart to dip the short bits of old cable already on the tubes in some epoxy to protect against microholes - leaks. TUNL assistance with ID PMT installation - TUNL will only be assisting with the ID PMT installation, for 8 man-weeks. - The most probable schedule for TUNL would be for Hoe and Michael to go between April 20 and May 15 to Sendai to help with OD cable splicing. - Neal and Mic would go to Kamioka from mid-May to mid-June. - If the OD cable splicing schedule gets pushed back, Diane may be able to go through early May. OD PMT analysis - Jason plotted up the data of the Random Count Rates vs Number of tubes. - Majority of tubes show random count rates between 2 and 20 (kHz) with most of those around 6 and 8 kHz. Back to top
March 2 -- KamLAND meeting notes ------------------------------------ Present: Werner, Chris, Ryan, Diane, Hugon, Jason, Neal, Hoe and Michael Discussion of ordering PolyEthylene flooded cable - Flooded cable is highly recommended and was used by Bob Svoboda in SuperK - Two possible US companies (Dacon and South Bay Cable - SBC). SBC cables were used by SNO and the additional water proofing is done with application of a liquid which solidifies on the braid. Diane is not yet sure how Dacon waterproofs their cables. - Questions include: How easy is it to remove this material for splicing? Is there a convenient tool for cutting this type of cable? - Kengo has been talking with the Japanese company Renei. - Flooded cable is thicker than normal cable (RG-58 is ~0.195 inch and RG-59 is ~0.242 inch). Precise info is required to make sure the proper connectors are ordered and the splicing technique must take this into consideration. - Decision on cable ordering needs to be made NOW, as we have to take into consideration the long delivery time from here to Japan. Signal cable splicing technique - Idea of small circuit board has been abandoned altogether. - Instead, a T-connector (2 US$ each) can be modified by cutting off one of the branches, leaving a straight piece. To this cut-off section, we will solder a small "board-type" 50-Ohm resistor (VERY cheap!). - This will give us the equivalent of a terminated Female-Female barrel (which is a costly 26 US$ each!). - The piece can then be attached to standard BNC connectors (Male - pin), which will be attached to the PMT cable and the long 40-meter cable. Shrink-wrap can then be easily fit over the connectors and T-connector - The other end of the 40-meter cable will also have a Male BNC connector. HV cable splicing technique - HV cable splicing can be done using a Female BNC connector on the PMT cable attached to either (1) a Male connector on the long HV (RG-59) cable or (2) a BNC Male-Male barrel which is then connected to a BNC female connector on the long HV cable. - This will allow the cables coming off the tube to be easily distinguished (signal has male connector, HV has female). - The other end of the long HV cable will have an SHV connector attached to it. - Questions for HV cable: How long will the cable need to be? Does the entire cable need to be waterproofed? - There still will be at least 12 type C (SuperK) PMTs which have the signal and HV together as one cable. A special design will need to be thought out. What we will need to order for the splicing - 250 BNC T-connectors which will be modified (2 US$ each) with 1/8-Watt 50-Ohm board-type resistors (also must be ordered). - 250 SHV connectors for one end of long HV cable (20 US$ each). - 750 Male BNC connectors for signal cable splicing. - 250 Male BNC connectors for HV cable splicing (or) 250 BNC Male-Male barrels (price?) with 250 Female BNC connectors. - Special crimping tool? - T-connectors should be ordered first. Ordering connectors is not as vital as we don't need them until we have the cable anyway! Other concerns - Due to the size of the shrink-wrap, we may want to look into getting bulkhead-less BNC male connectors. These are more expensive though. - Shrink-wrap comes in either black or clear. We would prefer clear so that we can see the splicing and the seal of the wrap on the cable Water sealing PMTs - Diane has talked to two companies, Permabond and MasterBond. - Both provide expensive sealants, and MasterBond claims they can add some extra material to the epoxy which will make it even more water resistant (though they will not guarantee it will keep the seal for 10 years). - Diane ordered a small amount from Permabond (50 US$ worth) and Hoe will help investigate its ability, using two glass plates attached to a cylindrical piece of PVC. - Torr-seal is not the long-term answer as it absorbs water. - What about RTV which comes in many different grades? -Temperature gradient is a concern for the epoxy/seal, as the tubes will go from room temperature into 10 degree (C) water. - Epoxy will be very expensive, as we will need large quantities of it per PMT as we need to insure a good seal. Travel - TUNL will be sending Jason, Mike, Hoe, and Neal to Sendai to perform splicing, mounting and water sealing. - Travel time is still uncertain, although sometime in May and June is likely. - Mike needs to be back to Durham on May 23 and Neal needs to be back by June 15. Back to top
March 9 -- KamLAND meeting notes ------------------------------------ Present: Diane, Neal, Ryan, Jason, Hoe and Michael Discussion of BNC connectors (both RG-58 and RG-59) and cables - Could order connectors as surplus or from a name-brand. The name-brand is clearly a bit more expensive, but probably a bit more reliable. - Pat will go ahead and order the BNC T-connectors separately (fairly cheap at less than 2 US$ each). - Diane has decided to place the flooded cable order with South Bay Cable (the company used to provide the SNO cables). - We still don't know where the cable will be cut into 40 meter length cables. - If done by the company, we pay a considerable price for that (several thousand US$), whereas if we do it here, how well can we insure the length of the cable within +/- 10 cm? - Plus it is still uncertain how much RG-59 cable to order for the HV cables. - Kengo seemed to be concerned that somehow the cables which we will send along one of the top beams to the spigot could be buoyant and thus potentially cause problems with the top PMT's. The SNO cables were specially prepared to be buoyant by the inclusion of an extra layer of foam PolyEthylene. Therefore, we believe that our cables will not be buoyant. Discussion of sealant used for water sealing the PMT's - Neal will look at possibility of some sort of Silicon sealant rubber. - Diane received the Permabond in the mail, but is unsure how to send some to Kengo. - The tubes that failed in Super-K seemed to be a result of the continual filling and refilling that was done. This would result in recurring cold-shock to the sealant. We have been told that is why roughly 20% of PMTs failed. - We will only add additional epoxy/sealant around Pyrex/PVC interface as this is the most likely point of weakness - Neal will look into obtaining a piece (or pieces) of unflooded Poly- Ethylene coated cable so that he can test the shrink wrap method over the splice/connectors. Work that has been done with the water tank. - Ludwig believes that the Tyvek bounce detection is finally working. Only way to be certain is to remove the Tyvek and make sure we see nothing in the PMT's when a throughgoing muon goes through both plastic scintillator detectors. - Hopefully in the next two weeks, Michael will be able to go back over to the optics lab and work some more on studying the reflectance properties of Tyvek under water (i.e. test the amount of reflected light to better accuracy. - Right now, our measurement suggests a reflectivity of 70% +/- 10%. - Michael will check to make sure the reflection is truly isotropic as has been suspected all along. Back to top
March 16 -- KamLAND meeting notes --------------------------------- Present: Diane, Ryan, Jason, Neal, Hoe and Michael Discussion of shrink-wrap and sealants - Neal has obtained a sample piece of shrink-wrap tubing from Raychem which has a large diameter and a shrink-ratio of 4-to-1. In a test application, the tubing provided a very good seal and there is an epoxy on the inner-lining of the tube to improve the seal. The epoxy flows easily and should flow into cracks, which is good. - Since we need to make the cables coming out of the OD PMT's water proof, it may be easiest to obtain some 2-to-1 (or 3-to-1) shrink-wrap which will be more flexible and apply it to the length of the cable coming out of the PMT. - Neal will look into the exact price of 500 feet of the shrink-wrap (4-to-1) tubing from Raychem. This does not include the PMT cable shrink-wrap, nor any used for the labels. One easy way to put labels on the cables is to apply a label-maker label and then put shrink-wrap over the label (this requires the clear shrink-wrap). - 500 feet estimate is under the assumption of about a foot of shrink-wrap to go over the splice/connectors for each cable (250 HV cables and 250 signal cables). - Neal says that GE will NOT guarantee their silicon rubber sealant over a ten-year period (but then again, no one wants to!). We still have not tested Diane's Permabond sample, but we are waiting to obtain some pyrex samples to test with a piece of PVC pipe. - We would like to know what Hamamatsu used previously as sealant on the tubes but obtaining this information appears to be difficult. Discussion of cable orders and cable trays - Diane has ordered the cable from South Bay Cable. We still have not told SBC if we would like them to cut the cable for us, but that can be decided at a later time. - Our OD cable has a transit velocity of 66% c, compared to 69% c for the ID cables. However, the OD PMT's have a shorter transit time so these two factors almost cancel. We are going to use 42-meter cable, since it will give us extra length and still be within specs. - There may be ID purification pipes running from the chimney to the wall, which would interfere with our cable trays from the 280 degree access hole to the north spigot. If so, adjustments will need to be made, such as a "cable-tray bridge". - Jason will make some preliminary drawings for where we would like to place our cable trays and send these drawings to LBL for when they confirm their cable routing. Discussion of work to be done with T-connectors - We received the shipment of T-connectors. Hugon has offered to have the UNC physics shop cut off the T-section and smooth it. Then, Neal will have someone solder on a 50-ohm resistors, giving us our 50-ohm terminated barrels. - Neal will test one of the T-connectors to make sure that the inside of it is brass, which is needed to make a good solder. - We still need to test the HV BNC connectors to make sure they can withstand the high voltages we will apply. Plan for shipping the cables and connectors - Send the 42-meter long cables with connectors on both ends straight to Kamioka along with the T-connectors. - This way, when we arrive in Kamioka for tube installation, we only need to connect the cables and put shrink-wrap over the connections. - This will allow for quick labeling and placement of PMTs during installation Other - Kengo will talk to Honda-Seiki about suggestions for what to do with the PMT mounting structures. - He will design boxes for shipping the PMT's from Sendai to Kamioka. Back to top
March 23 -- KamLAND meeting notes --------------------------------- Present: Werner, Ludwig, Diane, Hugon, Ryan, Jason, Neal, Hoe and Michael Mitsui OD construction - Mitsui is still working on finalizing a price and time schedule for OD. ID PMT installation - ID PMT installation begins June 5. They project that they will need 156 person-weeks, of which they request 12 from TUNL. - They will accomodate us in Kamioka, though we will need to provide our own transportation from the appartment to the cave. - Mic (N.C.State) is available all summer. We don't want to send Kengo there. Sealants - Kengo has contacted a Japanese company about epoxy for sealing the PMTs. It is a Urethane-based two-part epoxy and he will test it in water. - Hugon will obtain some Pyrex samples which Hoe will use to test the Masterbond and PermaBond epoxies. Water tank and Tyvek - Ludwig's work with the water tank downstairs is coming along. He believes we are seeing the Cerenkov light bouncing off the bottom and floating pieces of Tyvek and then down into the PMTs. - For 100 crossing muons, approximately 70 produce a signal in either of the two PMTs. To test that we are truly seeing the reflection off Tyvek we will remove the top Tyvek piece. - Ryan says that the detection of delta-rays then may be a concern. - We may see some reflection (<20%) off the water-air interface OD trigger threshold - Ludwig raised the issue of the trigger threshold. With the water tank, Ludwig can go no lower than 10 mV threshold with the P/S discriminator. - However, if we set the threshold too low, dark current may become an issue. Power supplies - Werner has requested using a Lecroy 2500-Volt, 300-channel power supply from Cal-Tech, but it is not available until August. Connectors/splicing - The T-connectors which arrived last week are not good for our purpose.Diane has reordered better T-connectors. - It was recalled that the signal cable off of the PMTs is NOT RG-58, so new connectors will be ordered for those cables. Other - Ludwig talked with Hank Sobel (Super-K) about Tyvek. Hank insists that Tyvek is the last thing we will install Otherwise, it gets very dirty and will not reflect well. - But how will we attach it to the sphere? This issue has not been raised, but may have to involve some sort of combination of hooks with wires, or some adhesive. - Will we order the Tyvek from the US, or Japan? Back to top
March 30 -- KamLAND meeting notes --------------------------------- Present: Hugon, Diane, Ryan, Jason, Neal, Michael and Hoe Discussion of ordered cable - SBC makes their water-blocked (or flooded) cable using an epoxy which dries between the jacket and the braid. - Neal will call SBC to find out information about this epoxy. If it is heat-activated, will it be disturbed when we apply the heat gun to attach the heat-shrink around the splices? Discussion of splices and water creep - In a teleconference last week, there was concern expressed about our plan of using BNC connectors in our splicing technique. If there is a water leak anywhere along the cable, water will creep down to the connectors, possibly shorting them. - One possibility is to crimp an extra wire to run from the ground braid across the splice to the other cable. This would work for the HV cable only. Signal cable would need to be designed. This scheme would involve considerably more work and would have to be done at Sendai. - Another possibility is to use RTV (silicon rubber) which could be applied to the end of the cable before we add on the connector. This would provide an additional seal to block any water which is creeping. - We may also want to put a compression fitting around the water blocked cable, which would possibly provide an additional seal. Such a fitting could damage the cable jacket, so we would need to put it near the connector so that it would be included in the shrink-wrap. Other - Diane already has the Pyrex from Hugon and will obtain some PVC to begin the test of the MasterBond and PermaBond sealants. - Diane has not yet gone ahead with re-ordering the T-connectors because it was unclear if our splice idea of connectors will be the final solution. - ID tube installation at Kamioka is delayed until at least June 12 and could be further delayed. - TUNL is not sending anyone to Sendai or Kamioka in May. Current plans predict sending people to Sendai in June. Back to top
April 6 -- KamLAND meeting notes --------------------------------- Present: Ludwig, Hugon, Ryan, Diane, Jason, Neal, Michael and Hoe for the HV cable only. Signal cable would need to be designed. Water leakage testing of BNC connectors - Neal will begin a test to determine how well RTV will seal against water creep. He has applied some RTV (rubber silicon sealant) on the end of the cable over the braid and dielectric. Then he added the BNC connector before the RTV was dry. - A large hole will be cut in the cable sheath and nitrogen will be sent through the cable. The BNC end of the cable will be placed in water, where he will look for bubbles. He will also place the open end of the cable in the water as well to see if nitrogen leaks through it. - Nitrogen will be used instead of water because the pressure can be increased up to 50 PSI. Upon sucessful completion of this test, we will perform the water test. But if the RTV can prevent nitrogen leakage, the test will be a success. - For now, Neal is trying with standard RG-58 cable (i.e. NOT flooded/blocked). He has asked South Bay Cable for some blocked cable samples and then will test them as well. Alternative splicing scheme for the HV cables - Diane received several samples of a special type of shrink wrap tubing. It comes in various sizes, but in essence it is standard shrink-wrap with either a crimp or small amount of solder in the middle. - We could use the small shrink-wrap (with crimp) to splice the center wire of the HV cable and then use a larger shrink-wrap (with solder) to splice the braids. Then a standard shrink-wrap can be fitted over the outer sheath. This method had never been tested before, but the company offered us a test sample. - It would be impossible to use this splicing method for the signal cable, as we would not be able to incorporate the 50 Ohm resistor. - If we decide to use this splicing scheme, it is rather labor intensive and would have to be done in Sendai. Water tank and MC simulations - Ludwig has done a preliminary analysis on the reflectivity of Tyvek with the tank downstairs. He is running with a small circle of Tyvek on the bottom and a larger circle on the top of the water. - Thus, a downgoing muon will have Cerenkov light that bounces off the bottom piece of Tyvek and then bounces off the upper piece and then into the PMTs. The water level is such that direct Cerekov light cannot enter the PMTs for a triggered muon. - Ludwig did two runs: one with both pieces of Tyvek and one with the upper piece of Tyvek removed. Comparison of these results with Ryan's GEANT (MC) simulations should allow them to obtain a good estimate of the exact reflectance of underwater Tyvek. - Thus far, Ryan's code agrees in general with Ludwig's results, but parameters will be adjusted to pinpoint the exact reflectance of underwater Tyvek. As of right now, Ryan claims that if anything, the PMT experimental efficiency seems to be a little higher than originally thought. - At the same time, Ludwig is working on a preliminary investigation of neutron spallation from muons. This was originally thought to be very difficult to measure, but Ludwig may have discovered a way to do it. Back to top
April 13 -- KamLAND meeting notes --------------------------------- Present: Werner, Ludwig, Hugon, Diane, Ryan, Jason, Neal, Michael and Hoe RTV test - Neal has been testing the RTV-treated cable connector under a water pressure of 40 PSI and has found no leaks after 1.5 days. In Kamioka, we should see no more than 30 PSI! - Neal used self-leveling RTV (GE number 112). How much would we need to buy for all of our connectors? - For those who are questioning the validity of our cable splicing technique, Neal/Diane/Hugon will explain it in detail on the web with test results from Neal's water pressure test. Other splicing components - Neal and Diane will contact Newark about getting brass T-connectors. - The ones we have currently are Zinc, and we can't solder the 50-Ohm resistors to Zinc. - Shrink-wrap will soon be ordered from Powell Electronics (ES-1000, size 4). It comes in 4-foot lengths, and we'll order enough to have one foot of tube per splice. - The tubing comes in packs of 75 so we will order 2 packs, giving us 600 ft. - We need at least 250 ft for both the HV and signal cable splices. - Cables will be shipped from South Bay Cable on May 6 and arrive sometime in 2nd week of May. Super K splicing - We still need to devise a plan for splicing the twelve Super-K tubes which have HV and signal cables rolled into one. We'll probably use the UT method using a small circuit board as well as Y-shaped shrink-tubing. Trip to Sendai - We will need to inform Kengo of which tools we will need so he will be ready for our arrival. Jason will arrive one week early to help prepare. Monte Carlo - Ryan's Monte Carlo is matching Ludwig's work downstairs even better than before, with a ballpark guess of Tyvek's Reflectance at 0.5 - 0.6. - Efficiency of tubes may actually be a bit higher than expected. - Ludwig will run with an increase in the voltage of 50 Volts to see if there is a difference in efficiency. Back to top
April 15 -- KamLAND meeting notes --------------------------------- Present: Werner, Ludwig, Kengo, Diane, Jason, Neal and Michael Pressure test of splicing techinque - During Friday's (April 14) meeting with Neal, Kengo was convinced that our design for splicing the cable (using RTV-treated connection ends along with the modified Tee connector encased in heat-shrink). - Neal has produced some drawings of the cable connections which will be placed on the web. Mitsui tube mounting design presented by Kengo - Mitsui provided detailed preliminary (NOT official!) drawings of their design for mounting of OD PMT's. - Since the hubs have already been welded to the sphere, we are restricted to going with L-beams with 720 mm spacing for the side-mounted PMTs. - We will bolt to the L-beams (not clamp!). But do we have Mitsui drill slots or holes in the L-beams or the mounts? - Design for top and bottom mountings is not detailed enough for us to envision how we will attach our existing frames to Mitsui's design in which they have four L-beam "arms" extending up (for bottom tubes) or down (for top tubes). Kamiokande frames - There are two types of frames. One is bent and ~10 cm longer. The slots are not located at the same position for both varieties - Mitsui is asking us to drill extra holes/slots in the existing frames. - Neal will take a closer look on how to deal with this problem. We would most likely have to have Honda-Seiki do the work, though it will be costly, as it will involve drilling in stainless steel. Assembly of PMTs in Sendai - 4 steps to the attachment of frame and shielding to PMT: 1) attach larger rubber ring around fat part of the PMT. 2) Attach the mesh to the ring, anchoring it to the rubber ring. 3) Attach a smaller rubber ring and the shield horn to the Kamiokande frame. 4) Place frame with horn over the small end of the PMT (which is facing up) and it is complete! - Add epoxy to the tube to provide extra sealing between glass and base. - Cut cable from PMT to about 1 foot. - Attach BNC connector and shrink wrap the 1 ft section. - Very conservative estimate of one working hour per tube per person. Back to top
April 18 -- KamLAND meeting notes --------------------------------- Present: Ludwig, Werner, Hugon, Kengo, Diane, Jason, Neal and Michael Travel dates to Japan: - Jason will go to Sendai around June 11 or 12. He will stay three weeks until July 1 or 2. - Mike, Neal and Hugon will leave on June 18 or 19 and stay until July 6. - There is a possibility to purchase plane tickets with an unfixed return date, which would allow us some flexibility in case there is extra work to be done (for example, on the frames). Cable lengths and routing discussed by Jason and Kengo: - In phone conference with LBL, it is clear now that our cable lengths will be 42 meters long (plus an additional 15 meter length add-on). - There are two or three of our OD PMT's which will be located such that the 42 meters of cable will only leave 90 cm leeway, which is not ideally enough. - There may be a possibility of routing the cables for these two/three tubes differently. Instead of going straight down the wall from the access hole and around the outside edge of the bottom, perhaps we could follow the curve of the wall on the downward path, saving us several meters of length. - This alternative approach would involve fastening the cable periodically to the vertical beams? Additional support for our splicing design - Neal cut into one of the standard (male) BNC connectors we have and found that there is an O-ring there. This would not provide a good seal if the connector is immersed in water. However, it may be somewhat useful inside the shrink-wrap, where the only water it could encounter would be a small amount coming from inside the jacket. Discussion of magnetic field effects on PMTs: - The magnetic field will affect the gain of the phototubes. We want all PMT's to have identical gain in Kamioka, which means some PMT's would need a special setting of HV. - Orientation of tube with respect to the frame will also affect the gain, as rotating the tube around its axis of symmetry will also affect the effective magnetic field effects. - There isn't much we can do about this, other than to calibrate with the proposed laser setup. Discussion of LED/Laser setup to test PMT gain/response in cavern. - Hawaii has devised an LED setup to accomplish this but they do not yet have any money. - We do not know what their design calls for in the way of placement of LEDs - If there is one LED per tube, what do we do about cables to these LED's? Do we have to provide them? - The alternative to LEDs involves a laser (or two) attached to a bunch of optical fibers, which carry the light to the face of the tube. But the laser would be most likely very expensive, and who pays for it? - Discussions with John Learned and Matsuto-san from Hawaii will have to take place soon to figure this out. - We would go with a mounting connector attached to the tube, to which the optical fiber could be attached. This could be done in Sendai while we assemble the PMTs Position of OD PMTs discussed as well - We will be allowed by Mitsui to get on the scaffolding to make sure that the location of each tube is correct. - We cannot be on the scaffolding (nor beneath it) while Mitsui is working on installation, for safety and liability reasons. Back to top
April 27 -- KamLAND meeting notes --------------------------------- Present: Ludwig, Werner, Hugon, Diane, Ryan, Jason, Neal and Michael Modification of Mitsui design - Neal came up with scheme to modify the Mitsui mounting design for top and bottom PMTs. It involves adding extra L-beams which would be horizontal and attached to the four vertical L-beam arms. - The horizontal L-beams will have holes drilled in them and we can then attach the Kamionkande frames to these add-on pieces. - To account for the fact that we have two different shapes of Kamiokande frames, we will have Honda-Seiki workers drill holes/slots in the frames (4 holes per frame) at the same location regardless of which type of frame. - Kengo received price estimate from Honda-Seiki for this work. It will cost US $10,000 for cleaning the frames, $8,000 for replacing the rubber ring, $5,000 for drilling 4 holes in each of the 250-300 Kamiokande frames, and $3,800 combined for the rubber belts needed. Discussion of Tyvek and how to attach it to sphere. - Widest width between ribs on the sphere is 3 meters. Dupont has confirmed to us that it is indeed possible to get 3-meter wide rolls of Tyvek, so there is no problem there. - Idea is to cut the Tyvek into 30-meter by 3-meter "diamonds" and punch holes in the edges. - We will need 20 of these diamond-shaped pieces, attaching them to each other to form a "Tyvek sphere. Holding the Tyvek in place would involve folding over the ends, stapling with stainless steel staples, and sliding a circular beam of steel through this "loop". This circular beam of steel can then be secured in place (one at the bottom of the sphere and one at the top). Discussion of 8-inch PMTs used for the chimney veto. - These tubes (20 of them) will be placed in oil, but how do we mount them? We will have Tohoku machine shop build the frames for this mounting. - Will we need to shield these 8-inch tubes from the magnetic fields of the Helmoltz coils? 8-inch tubes are less susceptible to magnetic field effects. - Since these tubes will most likely be very close to the inside tubes (where the magnetic field is cancelled, we would expect that our veto tubes should also be very near the cancelled magnetic field region...though where will the Helmoltz coils be exactly? Discussion of splice design and connector/heatshrink orders. - Neal will send a cable with the RTV-treated connectors to Japan so they can verify his water test. They will also most likely want a sample of the overall splice (involving RTV-treated connectors, the modified Tees and the heat-shrink, so they can test it's impermeability to water. - Tees will be ordered soon, though the brass Tees are more expensive than originally thought. We must order soon. - Heat-shrink must also be ordered soon, but since the signal cable coming off of the PMTs is RG-174 instead of RG-58, Neal has to modify the original heat-shrink idea. The heat-shrink we had intended to use will not shrink down far enough to satisfactorily enclose the RG-174. Back to top
May 4 -- KamLAND meeting notes --------------------------------- Present: Hugon, Diane, Jason, and Michael Berkeley meeting in early June - Ludwig, Hugon, and Diane (and perhaps Jason?) will be going. Kengo will be there as well. - We will ask for an hour's worth of time to present the "assembly" of OD, meaning frames, installation, cabling, etc. - We will need to work out details with Hawaii the method that will be used to calibrate the OD tubes. Hawaii's initial idea involves a large laser and 40 LED's in strategic places. But Hawaii only has US $10k to use. - We need to find out exactly what will be the point of the calibration? If it is simply to verify light production, we would still need to know the gain of a PMT for a given LED signal. Because LED's are solid state devices which will deteriorate faster in water than PMT's, future calibrations using this method will not be accurate. Discussion of 8-inch PMT's for the chimney veto - Twenty 8-inch tubes have been donated by RCNS. We propose that UT perform the refurbishment since they are doing it for other ID tubes. However, we are uncertain as to how these PMTs will be installed. - The 8-inch tubes will have to be tested, at least for the gain measurement. We could hopefully fit the tubes for our testing apparatus which was used for the 17- and 20-inch PMTs. - Who performs the installation of these PMT's? Other - All materials for the OD refurbishment has been ordered. Tees were ordered, and 200 will arrive next week, and another 48 will arrive in 4 weeks. BNC connectors will arrive next week. Heat-shrink tubing has been ordered, as well as RTV. Kengo says that there is an epoxy in Japan (used for tube sealing) which he can obtain from over there. - Honda-Seiki will go ahead and put eight slotted (oversized) holes in the Kamiokande frames. They will be using a punch instead of a milling machine, so we lose some accuracy and that is why we will go with oversized slots. The decision to go with eight holes instead of four is because eight holes is not much more expensive than 4 and it eliminates the need for Mitsui to build additional framework. Back to top
May 11 -- KamLAND meeting notes --------------------------------- Present: Ludwig, Hugon, Diane, Ryan, Jason and Michael Berkeley meeting (June 2-4) - Ludwig, Hugon and Diane are going for sure on Friday (June 2). Werner wants to go to and would also like to have Neal go as well. - The TUNL group will make an agenda for the meeting and send it to Suzuki. We will request that the OD discussion take place after Saturday morning. - We came up with the following items which we would like to discuss at the meeting: * 20" PMT Tests, Analysis, Assembly * OD Structure Construction and Installation * Tyvek Reflectivity Tests and Installation * 8" PMT Plan for Chimney Veto * Executive Summary: OD Status and Project Integration Other various topics - Jason will have to travel early to Japan (as will Mic) to arrive in time at Kamioka for the mine driver's training. This training will take place on June 9th. Kengo already has had this training. - Mic will be in Japan both in the summer and in the fall. - Housing in Kamioka will be taken care of for Mic and Geoff Milanovich, as well as for those people traveling in September. - For the trip to Sendai in June (for Jason, Hugon, Neal and Michael) we will need crimpers, wire strippers, connectors, RTV, heat-shrink tubing, soldering iron, heat gun, gloves, cable ties, etc. - The SHV connectors for the HV cable have not yet arrived, but everything else has arrived. - 3-meter wide Tyvek is probably the same price in Japan as it is in the US, so we will probably purchase it over there. It must be folded and cut (and holes punched and reinforced) and then stored in a clean fashion. In fact, it will be the last thing installed in the mine. Back to top
May 18 -- KamLAND meeting notes --------------------------------- Present: Ludwig, Hugon, Diane, Ryan, Jason, Neal and Michael Cables and connectors - Flooded cable has arrived from South Bay Cable. Werner and Diane are working out details of using the long FEL upstairs hallway for cutting the cables into the various lengths needed. - FEL hallway is carpeted and traffic-free for now. We will lay down a sheet of plastic and lay the cables on that as we cut them in order to avoid abrasions on the outer sheath. - Tee connectors have been worked on by the UNC machine shop. They were able to preserve the insulation as well as the entirety of the pin. - Neal has completed the first sample signal cable splice. He used a piece of 174 cable, put on the RTV-treated BNC connector, slipped a stainless steel "standoff" (one-inch) to increase the diameter of the cable near the BNC. Then, shrink-tubing is placed over the standoff and RG-174. The tee connector added, RG-58 cable connected, and shrink-tubing (one-foot length) encloses everything. - The standoffs (0.25-inch diameter) need to be ordered soon, since they will have to go with us to Sendai. Other topics - TUNL will be presenting the OD work at the Berkeley meeting on Sunday (June 4) morning. - Jason will leave for Japan (Toyama) on June 7th to arrive in time to do the mine driver training on June 9th. Mic will go at the same time to also do the training. - Neal and Michael leave for Japan on June 19 (Monday) and arrive in Sendai on June 20. - Jason is continuing data analysis of 20-inch PMTs. He is trying to get a value for the single photo-electron peaks and trying to fit the chanel/picoCoulomb calibrations. Back to top
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