1. NSF Baseline Review February 10-12, 2004 IceTop Tom Gaisser Bartol Research Inst., Univ. of Delaware Jan 28, 2004T. Gaisser, L3 Lead for 1.3.2 IceTop1

2. Hartill Baseline Review February 10-12, 2004 UW—Madison Jan 28, 2004T. Gaisser, L3 Lead for 1.3.2 IceTop2 IceTop functions A 3-dimensional air shower array for – Veto (i.e. tagging downward events) – Calibration – Primary composition from PeV to EeV – Calibration, composition analyses similar to SPASE-AMANDA but 5000 x larger acceptance wider energy range, better resolution IceTop at high altitude (700 g/cm 2 ) –125 m spacing between IceTop stations –E threshold ~ 300 TeV for > 4 stations in coincidence –Useful rate to EeV

3. Hartill Baseline Review February 10-12, 2004 UW—Madison Jan 28, 2004T. Gaisser, L3 Lead for 1.3.2 IceTop3 IceTop + IceCube: 1/3 km 2 sr Coverage to EeV energy

4. Hartill Baseline Review February 10-12, 2004 UW—Madison Jan 28, 2004T. Gaisser, L3 Lead for 1.3.2 IceTop4 Veto, Calibration, Survey Veto –Vetos all downward events E > 300 TeV with trajectories inside IceTop –Vetos larger events falling outside –Tags 5% of  background in IceCube for study via ~3 TeV showers hitting stations Calibration of angular resolution with tagged  bundles Muon survey of IceCube

5. Hartill Baseline Review February 10-12, 2004 UW—Madison Jan 28, 2004T. Gaisser, L3 Lead for 1.3.2 IceTop5 Cosmic-ray physics IceTop EAS threshold ~ 300 TeV –Knee of spectrum ~ 3 PeV –Transition to extra-galactic CR may be below 1 EeV (HiRes, AGASA) IceTop – IceCube coincidences –Measure spectrum, composition –Locate transition to extragalactic CR –Normalize potential extragalactic sources of high-energy neutrinos

6. Hartill Baseline Review February 10-12, 2004 UW—Madison Jan 28, 2004T. Gaisser, L3 Lead for 1.3.2 IceTop6 Small showers (2-10 TeV) associated with the dominant  background in the deep detector are detected as 2-tank coincidences at a station. Detection efficiency ~ 5% provides large sample to study this background. Showers triggering 4 stations give ~300 TeV threshold for EAS array Large showers with E ~ 100-1000 PeV will clarify transition from galactic to extra-galactic cosmic rays. IceTop: 80-station, km 2 EAS array with 125 m spacing

7. Hartill Baseline Review February 10-12, 2004 UW—Madison Jan 28, 2004T. Gaisser, L3 Lead for 1.3.2 IceTop7 EeV Detection in IceCube with shower background  Potential to reject this background for EeV neutrinos by detecting the fringe of coincident horizontal air shower in an array of water Cherenkov detectors (cf. Ave et al., PRL 85 (2000) 2244, analysis of Haverah Park) Penetrating muon bundle in shower core Incident cosmic-ray nucleus Threshold ~ 10 18 eV to veto this background

8. Hartill Baseline Review February 10-12, 2004 UW—Madison Jan 28, 2004T. Gaisser, L3 Lead for 1.3.2 IceTop8 IceTop Detector 2 m 0.9 m

9. Hartill Baseline Review February 10-12, 2004 UW—Madison Jan 28, 2004T. Gaisser, L3 Lead for 1.3.2 IceTop9 IceTop station Two Ice Tanks 3.1 m2 x 1 m deep (a la Haverah, Auger) Integrated with IceCube: same hardware, software Coincidence between tanks = potential air shower Signal in single tank = potential muon Significant area for horizontal muons Low Gain/High Gain operation to achieve dynamic range

10. Hartill Baseline Review February 10-12, 2004 UW—Madison Jan 28, 2004T. Gaisser, L3 Lead for 1.3.2 IceTop10 Technical requirements IceTop station must distinguish –Random particles hitting one tank –Small showers near one station –Larger showers (4+ stations hit) –Implications for DAQ Detector response –Integrated signal = energy deposited independent of location in tank –Time of 1 st particle to < 10 ns –Implications for ice quality, tank lining

11. Hartill Baseline Review February 10-12, 2004 UW—Madison Jan 28, 2004T. Gaisser, L3 Lead for 1.3.2 IceTop11 DAQ design goals Feature recognition Low-gain / high-gain Local coincidence Horizontal showers Calibration mode

12. Hartill Baseline Review February 10-12, 2004 UW—Madison Jan 28, 2004T. Gaisser, L3 Lead for 1.3.2 IceTop12 IceTop DAQ components IceTop Data Handler IceTop Data Handler HG Chan LG Chan. Tank 1 LG Chan HG Chan Tank 2 Station 1 Station 2 Station 80 DOM Hubs (10) IceTop Data Handler (SP) Vert. Sh. Trigger........ Global Trigger InIce DATA InIce Trig.Gen. On line ICETOP DAQ Hor. Sh. Trigger Common Event Builder DAQ Control Monitoring DOMs (320) 100 kB/s 32 MB/s 10 Hz

13. Hartill Baseline Review February 10-12, 2004 UW—Madison Jan 28, 2004T. Gaisser, L3 Lead for 1.3.2 IceTop13 IDH and Trigger Shower Trigger Time Correction Common Event Builder Global Trigger Hubs Separate Monitor Data Create stream for “station hits” Create stream for “tank hits” IceTop Data Buffer Post trigger data retrieval Monitoring Online In-Ice Trigger Horiz. Shower Trigger Trap calibration data Time Control DAQ Control (IceTop Data Handler)

14. Hartill Baseline Review February 10-12, 2004 UW—Madison Jan 28, 2004T. Gaisser, L3 Lead for 1.3.2 IceTop14 Detector design goals Primary: Produce blocks of clear ice approximately two meters in diameter by one meter deep. Each block is to be viewed by two optical detectors (DOM), which are to be “frozen in” to the ice. Secondary: –Bottom and sides of the block of ice must be covered with a diffuse, highly reflective material. –Entire assembly must be light tight. –The entire assembly must be insulated to an R value of TBD to Minimize the amplitude and suddenness of temperature variations Limit cracking of the ice Meet environmental constraints of the DOM.

15. Hartill Baseline Review February 10-12, 2004 UW—Madison Jan 28, 2004T. Gaisser, L3 Lead for 1.3.2 IceTop15 Detector construction plan Freezing based on natural ice growth on lakes. Clear ice is produced by a method known in the materials industry as “zone refining” which exploits the tendency of the crystal forming from the liquid phase to exclude impurities that concentrate in the remaining liquid. In a lake, the “impurities” (which include the oxygen fish need to survive) are diluted in the large volume of lake water under the ice. Top-down freeze allows accurate placement and “freezing-in” of DOMs at the outset Technical issues to be faced at Pole all derive from the need to conduct the freeze in a volume of water comparable to that of the end product. –Remove expansion water as ice forms –Keep dissolved air below saturation to avoid bubbles

16. Hartill Baseline Review February 10-12, 2004 UW—Madison Jan 28, 2004T. Gaisser, L3 Lead for 1.3.2 IceTop16 Status of detector development 2000-01: small tank at Pole –Pressure relief via heated rod –No degassing, no insulation 2001-02: full-size tank at Pole –Pressure relief via heated pipe –No degassing, no insulation. Freeze-time 28 days 2002-03: freeze 2 full-size tanks in commercial freezer in Delaware, one froze from top down, one from bottom up –Both methods work –Top-down requires cooling from bottom, DOMs freeze in at end –Bottom-up requires degassing, pressure relief; DOMs freeze in initially, bottom can be closed from beginning 2003-04: freeze two full-size test tanks at Pole –Insulated tanks assure uniform, flat freeze front, additional protection from thermal cycling. –Achieve good ice quality but –Freeze-time too long 2003… Construction of test station in lab for calibration, testing

17. Hartill Baseline Review February 10-12, 2004 UW—Madison Jan 28, 2004T. Gaisser, L3 Lead for 1.3.2 IceTop17 2001 test tank Viewed by 2 AMANDA analog OMs Cloudy ice but reasonable signals Currently taking data for comparison with station in lab

18. Hartill Baseline Review February 10-12, 2004 UW—Madison Jan 28, 2004T. Gaisser, L3 Lead for 1.3.2 IceTop18 Design of prototype tanks; 8 to be deployed in 04/05 with 1 st 4 strings Pallet Insulated tank DOM Support structure for DOMS and cover Freeze-control box* Pressure relief system Sunshade support* *Removed after freeze

19. Hartill Baseline Review February 10-12, 2004 UW—Madison Jan 28, 2004T. Gaisser, L3 Lead for 1.3.2 IceTop19 Degasser unit Dual unit: circulating pumps (black), filters (white) millipore degassers (outer units – connected to Vacuum ballast tank in freeze control box). Only one system at a time in operation. a) Before filling tank b) Near end of freeze under 85 cm ice

20. Hartill Baseline Review February 10-12, 2004 UW—Madison Jan 28, 2004T. Gaisser, L3 Lead for 1.3.2 IceTop20 Current test season at Pole Tank10 (1 m deep) – Filled Nov 22, 2003 20 minutes to fill < 10 RPSC man hours for transport and filling Tank09 ( 0.9 m ) –Filled Nov 26, 2003

21. Hartill Baseline Review February 10-12, 2004 UW—Madison Jan 28, 2004T. Gaisser, L3 Lead for 1.3.2 IceTop21 Cable runs looking toward MAPO away from SPASE Tank10 is on the right, Tank09 on the left. Power cable is on the left. There are 5 cables on the right: 2 freeze-control cables, two twisted quads for DOMS, and Stoyan’s cable to read temperatures during the winter. The latter is somewhat thicker than the other four.

22. Hartill Baseline Review February 10-12, 2004 UW—Madison Jan 28, 2004T. Gaisser, L3 Lead for 1.3.2 IceTop22 Tanks closed Jan 23-26 a) Dec 6 during freeze (cover used as extra sun shade) b) Jan 23 after closing, tent used as outer cover over black vinyl sheeting Tank10 during freeze and after closing

23. Hartill Baseline Review February 10-12, 2004 UW—Madison Jan 28, 2004T. Gaisser, L3 Lead for 1.3.2 IceTop23 4 IceCube DOMs now running From: SMTP%"john.kelley@usap.gov" 15-JAN-2004 15:56:19.45 To: icecube-c@ssec.wisc.edu Subj: First Four IceCube DOMs Deployed I'm pleased to report that the first four IceCube digital optical modules have been successfully deployed at the pole. They are currently frozen into two IceTop surface tanks, located near the SPASE building. The DOMs are operating normally, and we are looking forward to dark-adapting the tanks and taking real data. John Kelley, UW-Madison DOM frozen in place, Jan 15 ATWD waveforms in “scarface” --Serap Tilav, Jan 27

24. Hartill Baseline Review February 10-12, 2004 UW—Madison Jan 28, 2004T. Gaisser, L3 Lead for 1.3.2 IceTop24 Schedule for tanks PY3PY4PY5PY6PY7PY8 Strings deployed 4 12 16 18 18 12 Tanks Deployed: 8 24 32 36 36 24 Manufactured: 8 24 32 96 (accel) Freeze units (*) 8 (+2?) 16 (+2?) 12 0 manufctd (accel) Assumes each freeze unit reused up to 5 times. (add extras ?)

25. Hartill Baseline Review February 10-12, 2004 UW—Madison Jan 28, 2004T. Gaisser, L3 Lead for 1.3.2 IceTop25 Schedule Milestones Delivery of equipment for 03/04 deployment: 11/3/03 Post-deployment meeting: 3/27/04 Production readiness review for 8 prototype tanks: 6/15/04 Post-deployment meeting: 4/1/05 Second production readiness review 8/1/05 Initial In-Ice, IceTop Data System Integration Final Production readiness review 6/1/07

26. Hartill Baseline Review February 10-12, 2004 UW—Madison Jan 28, 2004T. Gaisser, L3 Lead for 1.3.2 IceTop26 Muon self-calibration procedure Take in-tank coincidence data for each tank for commissioning Compare to lab template (in water) Interpret deltas with simulations Fix parameters for interpretation of signals Add to data base Vertical  (defined by  -telescope) In-tank coincidence (defined by 2 OMs) broadened  peak + low energy e-m background Data with test-tank setup at UD in water. (Large negative amplitudes on left.)

27. Hartill Baseline Review February 10-12, 2004 UW—Madison Jan 28, 2004T. Gaisser, L3 Lead for 1.3.2 IceTop27 Initial calibration with SPASE SPASE: 30 m grid  threshold ~ 20 TeV –Intermediate between 2-10 TeV of 2-tank IceTop station coincidence and 300 TeV IceTop array threshold –Important energy region for background in IceCube (small showers with 2-3 muons) Provides tagged muon calibration and survey of first IceTop strings Provides calibration of IceTop tanks Sees IceCube strings from larger angle

28. Hartill Baseline Review February 10-12, 2004 UW—Madison Jan 28, 2004T. Gaisser, L3 Lead for 1.3.2 IceTop28 Hardware (capital) costs Capital –Tanks: 160 @ $6037=$965,920 –Frz units: 36 @ $6002= 216,072 –O’flow units 36 @ $ 561= 20,196 –Sunshade 36 @ $1922= 69,129 –Misc Tank Equip 38,550 –Test station Equip (inc. $45K at UWRF) 75,000 –4 test station tanks + ancillary equip 60,000 –Computer cluster180,000 Total capital$1,564,867 (+$60K)

29. Hartill Baseline Review February 10-12, 2004 UW—Madison Jan 28, 2004T. Gaisser, L3 Lead for 1.3.2 IceTop29 Materials & supplies (inc shipping) + travel (both unburdened) 1.3.2.1 Tanks$ 18,850 »(not enough for shipping) 1.3.2.4.1 (Test stations) 31,000 1.3.2.4.3 127,750 –DAQ computers 27,000 move half to 1.3.2.1 –Misc hardware 100,750 move to 1.3.2.4.1 1.3.2.5 -000- 1.3.2.6 48,000 »(replacement work stns) Total M & S$225,600 Travel$549,000

30. Hartill Baseline Review February 10-12, 2004 UW—Madison Jan 28, 2004T. Gaisser, L3 Lead for 1.3.2 IceTop30 Labor Costs FTE years (by institution for total project) UD: 34.3, UW: 3.5, LBNL: 0.7, UWRF: 3.6 By Individuals involved part-time Scientists: UD:13 UW: 1 LBNL: 0 UWRF: 2 Engrs, techs: UD: 5 UW: 1 LBNL: 2 Labor cost by Project year (burdened, $ M) PY 345678 1.221.271.130.910.56.0.44 Labor cost by WBS element ($ M) Tanks: $1.18 Cables: $0.30 DOMs: $0.22 Engineering resources: $1.32 Detector Simulations: $1.02 DAQ: $0.56 SPASE: $0.43 Management: $0.50 Total Labor cost for 1.3.2: $5.53 M

31. Hartill Baseline Review February 10-12, 2004 UW—Madison Jan 28, 2004T. Gaisser, L3 Lead for 1.3.2 IceTop31 Staffing Plan FTE per project year PY3: 7.5  8.8 –Hire technician starting June 1 –Part-time post-doc starting Sept 1 PY4: 8.8  9.4 –Hire Junior faculty member PY5, 6 7 8 8.3 6.9 4.4 3.8

32. Hartill Baseline Review February 10-12, 2004 UW—Madison Jan 28, 2004T. Gaisser, L3 Lead for 1.3.2 IceTop32 Issues/Risks First priority: speed up freeze time –Redesign of sunshade underway –Engineering study to reduce insulation Aggressive hardware schedule: –8, 24, 32, 96 tanks in successive years How to implement transition of effort to data handling, detector verification (and operations) as construction progresses

33. Hartill Baseline Review February 10-12, 2004 UW—Madison Jan 28, 2004T. Gaisser, L3 Lead for 1.3.2 IceTop33 Summary IceTop provides valuable calibration, survey and veto capabilities for IceCube. The possibility of a surface array over a -telescope is unique to IceCube. The result is a kilometer-scale, three- dimensional air shower array, A novel tool for cosmic-ray physics to EeV energies with likelihood of significant discoveries related to neutrino astronomy