Milagro meeting LAMPF Auditorium 12 -13 Feb 1997 



Index
Day 1 - June 12,1997
Cy Hoffman    What we need to accomplish today  tomorrow
Gus Sinnis  Rich Miller    Status of Milagrito  Site 
Jordan Goodman    General Budget Issues
Jordan - Planning and Timetable  (Gantt Chart)
Andy Smith et al  Status of Milagrito Reconstruction
Jordan
Gus
Isabel Leonor - Calibration
Peter Nemethy - pedestals
Rich Miller - Fibers 
Tony Shoup    PMT/cable/encapsulation status, plans
Todd Haines    Safety  Training
Michael Schneider    Water System    results, plans 
Todd    more water stuff
Linda Kelley    Electronics Status/Plans
Tony Shoup    Outrigger counters    design, cabling, fence
Cy Hoffman    Review of What We've Done Today 
David Williams    Reflectors/Baffles for PMTs 
Day 2 - June 13, 1997
Don Coyne      Cover Modifications    Needs and Plans
Cy Hoffman    Plans for work this summer 
Don Coyne    Lightning Protection System (Status)
Gus Sinnis    Milagrito Disassembly 
Morgan Wascko    Igloo Results
David Williams    Muon Layer Design Discussion 
Gus    current status of igloos 
Peter Nemethy    Peter Installation Scenario
Jordan Goodman    Review of Plans  Budgets
Stefan Westerhoff et al.    Monte Carlo Simulations 
Gaurang
Mei-li
Stefan
Discussion on Analysis  Data  Taking Strategy
Cy Hoffman What we need to accomplish today tomorrow Decisions that allow us to install Milagro next summer Muon layer igloos or simpler? if igloos, what kind? Installation strategy wet or dry? cover disposition? when to start? how long? how many people? how to dismantle Milagrito? Cables what length?, what kind?, patch panel? Other changes? What present at ICRC moon shadow? Milagrito analysis strategy calibrations, slewing, event fitting, Monte Carlos Outrigger detectors design, cabling, electronics, fence Modifications to Milagrito calibration system, PMT replacement, pub trailer cable plant patch panel Back to index Gus Sinnis Rich Miller Status of Milagrito Site Data Taking, Operations, etc Gus DAQ System FASTBUS no problems VME, SGI no problems Front End Boards 1 fried channel (we did) ~ 4 different channels being looked into PMTs 10 already dead (10 more died previously and were replaced), 1 died last week mostly infant mortality, things seem to have settled down Cover some light leaks, repaired, mostly okay Water system several problems pumps died, water hammer, pressure too high, system leaked, carbon getting by the 1 micron filters, cannisters rusted through, water bugs failed (cold solder joints) leak did not turn off system solutions pump motors replaced (were good, now have spares) installed flexible pvc from pub to pumps installed uvlamp shutoff retrofit on filter cannisters (there was a defect in the cannisters, sent in for repair) running 200 gpm since May 16 smallest filter is 0.5Fm Running time 77% live time since Jan 30, or 85% if exclude the zeros in the last month, most down time owing to MG reset Back to index

Rich Milagrito running 2.095e9 events, 117 DLT archive tapes, 2.34 TBytes of data 1 tape per day Experiment control relatively easy web run mostly Shift running has been easy only one emergency, that was water problem on 28 March the MG set has tripped gt 5 times log book usage is still not totally regular he urges people to use it more frequently Some milestones more on vugraph Regular data taking started 8 Feb 1997 online reconstruction started 4 Apr 1997 Made a small Milagro shift cheat sheet to attach to badges need 10 minute training on how to do shift Back to index

Jordan Goodman General Budget Issues timetable Not a good year at the NSF. Ongoing battles with them about both construction and operations Projected to get $584k construction, $190k operations Has cost estimates (to finish Milagro) available on the web Total remaining to spend $1m, with contingency $140k NSF giving us 454k construction 97, + 360k next year 98 with payback on operations (?) Program review? bring them on! just a threat? or an offer for more support? we need notice, however, and prefer that they not come during summer will the NSF pay for a tech at the lab? they are not willing to fight that issue accepted the idea of 0.25 tech $145k operations including utilities we're pretty close but flow of money is still problematical have to defer some purchases until next year computers (that we don't need until Milagro), outrigger array, 150 PMTs (though we must have the money early for these may have to sit on Eisenstein Important we have to order the tubes by Feb 1st to have them by August 1st!!) Planning and Timetable Jordan has a Gantt chart! Operate Milagrito thru 15 Apr 98 Cover design study finished now (??) Cover mods July Oct 97 Lightning system study done Lightning install June July Muon layer design study to be finished by end of July Install wiring from pub to counting house by end of summer Prototype outrigger array July August ~100 boxes? Muon layer box procurement Fall 97 what about building almost too late now PMT testing encapsulation by batches everything done by August 1 1998 (?) Electronics in by Jan Feb 98 test with readout Drain pond starting 15 Apr 98 Remove Milagrito tubes by 1 Jun 98 Survey Grid, Clean Pond by end of Jun 98 Install Muon/Hadron Layer by late summer (beginning July to end of August) Install Calibration System late summer Final cleaning in August Start filling pond by Sept 1 EAS layer installation from raft should practice this summer to see if practical Continue fill through early fall Install outrigger array Debugging run including muon layer Start data taking in 1 November 1998

Click here to get postscript file for the schedule" Back to index

Andy Smith et al Status of Milagrito Reconstruction
Software still has problems
10% showers fail fit losing most of the muons?
what to do about late light? small pulse heights are late by a lot (100 ns?)
resolution is still not understood, possibly a function of zenith angle
decreasing number of hit tubes for high zenith angle (shadowing of berm?, or maybe spectrum of GCR folds in? very sharp break around 50 degrees)
50% of hits fail to be included in the fit
Jordan
not ready to write papers yet still trying to understand how the detector works
We throw out a lot of tubes, and do we understand why? beautiful showers are beautiful but smaller showers are a mess if you get more than 150 tubes, you throw fewer and fewer tubes out they're all nailed (10 pe's minimum)
cooked up parameter to measure robustness of shower fit take each tube, shake the times by a Gaussian (~2.5 ns) new fit shouldn't change by much del angle between fit wiggled fit peaks at 0.5 degrees, long tail
del wiggle parameter gets much worse at zenith angles greater than 40 degrees, strong rise above 65 degrees to 2 degrees and more resolution at 53 degrees is 1.2 degrees or so
del e o exhibits similar behavior
foreshortening of array at large zenith angles is an effect that contributes to this problem
of course average trigger energy increases at large zenith angles
Gus
shows event displays with different cuts to see how the angle difference and the quality of fit depends on the cut chi sq improves with 1pe cut, more with 2pe cut and fit seems to be converging and stabilizing as cut is more severe but still get large angle changes (tail up through 14 degrees) yet del e o does not change much at the peak (though tail diminishes) we're looking at 1.5 degrees at the peak, with a long tail indicates some intrinsic in slewing, calibration, etc. Also fit larger fraction of showers when making stronger cuts.

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Isabel Leonor - Calibration

Isabel described the calibration system optics. Light is monitored by a photodiode before the filter wheel.

Data was taken at 13 filter wheel position - 4000 shots optical densities vary from 0 to 4

She describes the slewing corrections she is working on. Specifically she describes when she switches from low to high pmt. She then showed that for most channels a 3rd order polynomial fit fine but in some cases a 4th order fit much better. Some fit very poorly no matter what. She showed a map of which tubes could be best illuminated by which laser ball.

4 tubes had a bizarre relationship between falling edge time and tot.

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Peter Nemethy - pedestals

need to find timing pedestals -

A getting peds from laser calibration -

assume laserballs are at nominal location.

Get tpeds from slewing corrections and tube positions.

By using far away tubes we can reslove the ambiguity between laser ball position and pedestal ambiguity.

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Rich Miller - Fibers - A large fraction of the fibers leak light. The 6 dark cladded fibers work well. The others don't. New fiber is the answer. We need 3750m of fiber it may cost ~$1.50/meter.

There is a question as to whether we need to calibrate the igloos with a laser.

We should put some fibers in a few igloos for intercalibration.

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Tony Shoup PMT/cable/encapsulation status, plans

PMTS -We need to order 100 PMTs by Feb 1 in addition to the 200 we are ordering now to be ready

  need to finish 800 cables for the pond $49k 
  what should short cables be made of? 
  do we want to do a different cable routing pub count house? Box on outside might need longer quot short quot cables have to throw away the 75 ft cables? 
  the cables in the pond for the air shower later should be 20 ft longer, 490 number
  use rg 59 for the pub count house need 800 x 100 ft = 80,000 ft or 80 spools ?
  rev Scott Neil will make a proposal in the next fortnight about the pub counthouse cables

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Todd Haines Safety Training We have to take safety seriously, especially as regards visitors experiment could be taken down if we're not careful. It's everybody's responsibility. Milagro site (our requirements) need site specific training Gus is revising the need first aid and cpr that's up to date some discussion about rescinding this requirement, as the courses seem tobe too trivial. We've decided that it is sufficient to have taken the course once, not necessarily that the training is current. If you visit LANL for gt 10 days, you have to have GET training (2x0.5 days or can test out) LANSCE site specific training A training plan TH will do for everyone signed safety commitment P 23 new employee visitor checklist In addition students must do student hire checklist have an assigned supervisor mentor participate in local student activities Back to index

Michael Schneider Water System results, plans (including rainwater?) How are we doing? poorly at 5/16/97 pond is lt 3m at 3000C, but after the 1Fm filter better Internal welds and feedthroughs of the filter canisters are rusting through 2 have been shipped back to the manufacturer to be replaced, other 2 yet to be done Charcoal found all over the filters did not seal properly in the filter cannisters retrofit has addressed this problem Water at 5/20/97 shows we can make 10m water (at 43500 C 7m at 3000 C) why? confirmed by 5/27/97 not going through the softener to reduce the pressure, but both 0.5Fm and 1 Fm filters this is water going back into the pond But how is the pond itself doing? 5/27/97 is overlapping original 9/16/96 line but in the interim things were better 4/11/97 is highest curve, 3m at 3000C and even the 5/16/97 curve is higher than the latest one things going bad in just 11 days Is something happening in the pond that happens faster than we recirculate? Chemical reactions or biology? Propose a change put the sand filter (10 15Fm filter) before the charcoal filter to protect the charcoal from the incoming particles but need to protect the rest of the system from the charcoal. Better to take current charcoal filter, put sand into it then buy new, larger, tank for the new charcoal filter 62 inches diameter rather than 48 then put a 20Fm filter in series with the 1Fm filter (instead of 2x1Fm filters in parallel). The new charcoal filter tank would be about $10k, electropolished onetime investment. We really need the 200 gpm flow (part of existing problem is that high flow breaks up the charcoal, so need larger tank). Filter changes on the 20 and 1, 0.5 must be done at the same time turn off the flow and do it 5 minutes job must be done every 3 4 weeks Igloo plumbing quick connect at $20 per igloo delrin disconnect stops the flow needs 30 psi, which may be a problem for the pond filtration system owing to backpressure maybe a separate, simpler system just for the igloos, assuming that water eventually has gone through the pond filtration system Back to index

Todd more water stuff Issues what to do about the media filter (presently by passed because of backpressure) what to do about backflush from softener aren't allowed to put it on the ground when do we fill with more water, and how much? Status softener lt 1 grain hardness ( lt 17 ppm), 40 tons NaCl supply pump miswiring has been fixed, we have two spare motors filter tanks sent for repair 5/16/97 analysis water also sent to commercial outfit Roy at SouthCoast Pollution Control from 0.5 Fm, lt 1 ppm small and large from pond , lt 1 ppm large, 10 ppm small but this may be wrong contaminated with 0.3Fm particles or oil or other organics? Back of envelope Attenuation length in cm = 13 x radius in microns, x density in particles per cc. If lambda is 500 cm, particle size 1 Fm, density must be 6e4 per cc, and total volume of particulates is only 2 cc was sticking to cover or liner, and just coming out slowly? Can we use rainwater that lands on the cover? Need to run it through the filtration system, but prior to that we need some pre filter to catch leaves and vermin. There are some unfinished lines, but we also need pump in the catchment basin the outfall on the west side of the pond. Can't use one of the submersible pumps, but maybe one of the trash pumps. Argument about what to do about filtration system Todd argues for understanding what is happening in the pond, others saying we ought to do the changes Michael suggests even if we don't understand what's happening in the pond, because it's a problem that will have to be addressed anyway. Everyone agrees we should change filters so that we have a 20Fm and 1Fm filter in series so as not to plug up the fine filters with junk. This may be just a valve configuration change not clear or have to splice in a new canister (not a big deal) after the multimedia filter. Or put in 2 of the 20Fm filters, one after the softener (as Michael suggests). Back to index

Linda Kelley Electronics Status/Plans ECL boards 2 substantial changes for solar physics individual scalar output header changed to low TOT, and another low threshold multiplicity output there is a 5 prototype run that will be back by 6/20 for testing of these changes by another 2 3 weeks, we should know whether further changes are needed so we'll have boards this fall for testing the solar physics design mods Analog boards one correction no change needed to the films or prototype How many boards do we make? total channels gt 1100 , giving ~75 boards we have 20 ECL, 25 Analog if we make 50 55 new, we'll ahve as many as we'll ever need ~1 month leadtime needed but 3 months if we decide we need more later (?) assembly cheaper houses? ECL can be done in house at UCSC, but analog has too many components for that Schedule begin ECL fab ASAP ready for assy end of July begin Analog fab in mid July, ready for assy end of August use student labor in the summer, allow time for extended assembly more testing all boards will be ready and tested by the end of fall probably December ready to install at the site in February Channel count pond 450 + 228 + 170 = 848? Decide to go ahead make the 55 more of both kinds of boards, but defer decision of populating all of them until later Back to index Tony Shoup Outrigger counters design, cabling, fence Monitoring tanks and shmoos in tank need to keep track of certain physical measurements, like temperature, water quality, etc. We don't know how well it's doing over time, since it's only been in the data stream a short time. To maintain quality perhaps just fill once, disinfect with hydrogen peroxide, and then never open again. Or considering that it's just 2500 gallons per tank just periodically dump and renew. Want to improve the mounting of the PMTs in the tank. Estimated cost ~$350 per tank (not including shipping, made in Wisconsin, so shipping might be expensive). cabling in conduit? certainly use old stuff (old shmoo cables)? watertight connectors? connector is out of the water in the present design, but is exposed to the atmosphere can use cheap connector, but with a cover (like the covers on the shmoos?) deployment where when, who, how do we use shmoos? Gus would like to use 100 phototubes from the shmoos for the air Cherenkov experiment how many shmoos, how many tanks what's the appropriate mixture have a limited number of Hamamatsu tubes that we can put in tanks tanks are arguably 10x better than shmoos so 20 tanks would be as good as all 200 of the shmoos tanks have further advantage in that detector physics is more similar to the pond best use of shmoos is to extend to bigger array, higher energy how high do we want to go? if to 20 TeV, need no shmoos at all part of the answer should come from Monte Carlo studies string of pools, string of shmoos or patches determine optimal density of outriggers versus distance from the pond use outriggers for timing? then need timing studies with existing outriggers is the water tank good for timing, or does the internal reflection kill you? first sharp rise time may be okay comes from first reflection on the bottom can correct for that Back to index

Cy Hoffman Review of What We've Done Today Calibration system decided to buy new fiber, continue using fiber balls no laser ball in every muon box, but in samples of them need deployment scheme cooling/heating problem in laser shack taken care of ICRC papers Jordan gives first light paper Dave gives poster on Simo results moon shadow paper will become whatever we need it to be expect a miracle PMTs Jordan's schedule is okay, but tight for getting last PMTs here have to pester theNSF not agreed how many PMTs we will have when this is over uncertainty involving couple dozen tubes Cables air shower layer will have 20' longer cables than we have now re use the existing cables in the pond for muon hadron layer, but we need some 100 more and what length? not decided probably best same length as existing cables from pub to counthouse use rg 59, and need somewhat longer cables than we have now. likely can't use the ones we have now, prefer soft, pliable cables. Use scheme of Neils to have a box under neath the trailer with a patch panel. Can use old Cygnus cables, which are a good length for this. Apparently we will throw away the old pub counthouse cables, which might be worth $5k. patch panel design needs lightning system design before finalizing (conducting or not?) Water system decided to add a 20Fm filter upstream of the charcoal tank, maybe after the water softener, but will try to understand what's going on in the pond before reversing the sand and charcoal filters Electronics will purchase 55 ish boards, but not decided how many will be stuffed have another month to make that last decision we should be able to come up with a minimum number 1000 channels seems right. Back to index

David Williams Reflectors/Baffles for PMTs (advanced from tomorrow schedule) Anecdotal evidence of bad light trigger rate at 25 tubes is gt 5kHz, scaler rates in tubes show time structures that are sometimes seen by several tubes are there tubes that emit light? tube 177 was doing this, and has lately died, acausal hits neighbors with signals separated by more than their distance tubes rejected from fits never early, but late might be shower light arriving at tubes from different paths than expected So make a baffle that will limit the field of view of the tubes simple cones of Everbrite wrapped around the tubes downside would cut you off at large angles calibration might be a little harder also an additional reflecting surface might be a bad thing to have in the pond and you don't want to get rid of light Recommends doing this for a few tubes this summer to see if this gets rid of some of the bad light Some bad light coming through the acrylic cap on the PMTs, and this ought to be fixed at the minimum. Make the caps on the PMT opaque (now acrylic, make pvc)? But this change might cause other problems better to put an opaque barrier within. 13 Jun 1997 Fri 8 59 03 Back to index Don Coyne Cover Modifications Needs and Plans the continuing saga Model not infinitely trustable dynamics ok for long features, ditches not modeled properly, and winches tabs in model are infinitely capable. Have to learn when to trust it and when not to. Propose flexible couplers that can free the line or couple the line to the membrane, spreading the force over a patch, and that can be assembled cheaply from readily available components steel D's and O's. This gives a quot tunable quot design, where you can adjust the pressure delivered to the cover and the straps. Video shows model stability increased with diagonal quot quilting quot straps (just strung across, tied at the ends, not tied to the cover) in general stability increases with greater tension on the straps. When transiting between stable modes (low cat, high cat, bubble), the cover is still unstable in a wind. Stability results from either stressing the cover or putting a fine mesh over it so far we've tried neither in real life. But there are lots of possibilities how do we choose? Prefer doing everything, of course, better winches, straps, connections, and quilt, including concrete piers for the diagonals. This option costs $106k. Quilt alone may work, needs no cover mods, and costs $32k Don is not confident enough in this one. A compromise would be 2 diagonals only, plus winches and cover mods (new tabs envelopes for some lines (~1/2), not all) for $50k. If all lines tabbed and enveloped, $86k . This seems to be the preferred option (#2). Decide contract Neal part cover mods, multi mode connector, for option #2. Operate in this mode this summer, to see if we need the diagonals, while at the same time pursuing the contract for the diagonals (mainly concrete piers, done by PM).When the contract is just about in place, we will be able to decide whether or not we really need the diagonals and proceed accordingly. Neal's part will necessarily happen more rapidly use the guilt factor. Back to index Cy Hoffman Plans for work this summer cables, water system, fence, patch panel, PMTs On water we will do the 20F filter before C, more water studies, including trying to use rainwater. Delete this last option On the patch panel get it out of the way of the water system On the PMT's diagnose failures and replace? we should do this install test the new encapsulations? also we do this install test baffles reflectors? we will make some and install try some PMT's with opaque bases? we ought to try this too, with new glue On cover mod's start with Neal mods, as discussed above Pre installation studies learn how to work in water with raft will do in changing the PMT's Deploy more outrigger tanks Tony will order 16 (a 4x4 patch, or cluster plus trailers), labor for installation will be needed Fencing will also be an issue Lightning system definitely much work, some shutdowns Upgrade the calibration system Richard, at the same time as PMT re installation Igloos ? Cut an igloo open and examine it. Back to index Don Coyne Lightning Protection System (Status) Faraday cage scheme has converged Bidders' feedback has confused some issues Cu, or Cu coated steel? sliders? or raising cables? cables in the pond? decide not to do this! Construction 5 bidders, ranging from ~100k to 200k Perhaps deal with pros for boring climbing, and we do bonding, raising, ditching(?) piecemeal approach using quot mountain men quot contractors Cable bulkhead should be metal? Actually need more tests Other parts of LPS left up to hardware subgroups Schedule DC here June 22 29 liaison with Staley ICRC takes out part of July August do we wait until fall? Back to index Gus Sinnis Milagrito Disassembly Drain pond 3 million gallons @ 200 gpm 2 weeks Remove PMTs take them out 2 days (put them in in one day) may take a little longer because pond is damp and tubes have to go up not down Re encapsulate yes, but here, not Irvine or table decision until we've seen some Remove igloos Cables Leave 'em in, but seal the ends? 0 days seal the ends with UCI system 1 day rip out fibers, keep the floats Clean Pond 1 week Back to index

Morgan Wascko Igloo Results Triggered on scintillator paddles above below the igloo (paddles only on #1 #7), also on tubes (6/16) immediately surrounding the igloo. Get a result on paddle triggers, igloos 1 7 see 30 and 24 pe's per muon. Seven measurements (each a day's worth of data) in half a year show fair stability in igloo 1 data taking for igloo 7 has only recently begun. Back to index

David Williams Muon Layer Design Discussion Concludes the igloos are hard to beat! Double density hadron layer works ok. We should choose to build the igloos, but not if cost is gt $1k per igloo. The denser hadron layer remains available as a low cost option. Results for gamma hadron separation With Muon Layer Counts gt 5 pe's in a muon box as a muon muon layer pulseheight distribution gives a very clean separation between hadrons gammas. With dense hadron layer Can get a separation between hadrons gammas in the denser hadron layer, but it is much poorer. Can make quot staircase quot cut as a function of total number of pe's in the hadron layer Quality factor at 1 TeV, schemes are indistinguishable, but above 30 TeV, get much better separation with the muon layer We should install igloos as a right path for doing muons, with the option later of making a denser hadron layer as an enhancement to Milagro for lt $0.5M Possibility of using some of the extra tubes to make a small dense section in Milagro, but maybe we should just make it bigger rather than denser 58 tube increment (170 to 228, same as present Milagrito). Back to index Gus current status of igloos shoebox design, trapezoidal outline for stacking Central Container Company of CA came back with price quote description $1200 Roy has a different supplier, different price quote, $375 difference is in strength, sturdiness and thickness, cheaper one will barely support itself, and will need braces to support the PMT's. Material is all HDPE. Time to assemble after delivery Tyvek plus water inlet couple hrs/box How long can we wait to decide whether to build or buy igloos? Gus thinks we can decide in August. Four months may be enough time to build, but we don't know where to do it or how to store them. Back to index

Peter Nemethy Peter Installation Scenario Here's the putative schedule, most of which will occur under high catenary mode Remove Milagrito 3 days/12 p PVC grid fixes 3 days/6 p pond cleanup 6 days/12 p survey 3 days/3 p + prof inflated coax cable plant 6 days/8 p fiber optics conduits strings 3 days/4 p 162 igloos install, plumbinb, anchors 12 days/12 p dry install muon/hadron pmt's 2 days/12 p sig/hv test all pmt's 2 days/4 p (fill to submerge) inspect/untangle snake dance 2 days/4 p replace dead pmt's 2 days/4 p (fill to ~4 m) (continue filling) wet install shower layer 10 days/12 p inflated (450 pmt's, 50 per day) sig/hv test all pmt's replace 4 days/4 p shakedown run with tube still floating Y These are calculated as 10 hour working days Integral of working days 58, not including time for fill there are 20 working days per month, so this is essentially 3 months. We need a high duty cycle lots of days when we're allowed to work, and lots of time working on those days. We need to be able to stay in catenary with rainspout overnight and in rain, to keep the duty cycle high, and avoid the quot drop sweep quot mode. Back to index

Jordan Goodman Review of Plans Budgets phototube budget how many do we have total when everything is done? To date 450 full price tubes 116 half price tubes To be ordered 350 paid for Total 916 total Lost 20 broken 7 sold (will be bought again) 10 in the pond are now dead, may be broken 10 or so are missing, will probably be found Available 890 quot 20 Design 450 air shower layer 162 muon layer 162 or 200 in hadron layer if these tubes are centered above the muon tubes 190 or 228 if these tubes are at the corners (below the air shower layer) Total goes from 774 to 840 Available for outriggers 50 120 tubes we also have ~30 Burle tubes that can be used for these Back to index

Stefan Westerhoff et al. Discussion on Monte Carlo Simulations will probably get together as a smaller group to decide where this is going Gaurang has document of real cosmic ray fluxes Parente et al Astroparticle Physics 1995, 3, 17 compilation of various data protons 1.73e4 e^ 1.81 for E_ 100 GeV, flux is 5.14 m^ 2 sr^ 1 s^ 1 above 1 TeV 0.89 shows simulation starting at 100 GeV, 80 tube threshold, varying attenuation length in the water at attenuation of 6m, get 350 Hz, at 4m get 275 Hz thus our trigger rate is a sensitive measurement of the attenuation length Mei Li Chen UMd ++ (+Berley + Ellsworth) using EAShower + Milagrosim Stefan using CORSIKA + GEANT make working group on Monte Carlo anyone who wants is welcome Back to index

Discussion on Analysis Data Taking Strategy Are we ready to sacrifice some virgins? Finish calibration first! Candidates Moon, Mrk 501 (Stefan NO!), Crab, Mrk 421, Y other possibilities multiplicity single muons use to predict what we're gonna see Need a plan first Need to learn how to reconstruct first How can we make an energy cut for sure then we would be able to do the Moon Look at large showers, small zenith angles Some arguments for using the Crab as a standard candle gammas rather than just protons go ahead and sacrifice? Agreed that this discussion can be tabled at least until the next collaboration meeting while we understand all the things that hinder our reconstruction slewing, curvature, etc Back to index