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. NSF 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. NSF 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 1450 2450 m

4. NSF Baseline Review February 10-12, 2004 UW—Madison Jan 28, 2004T. Gaisser, L3 Lead for 1.3.2 IceTop4 Calibration, Veto, Survey Background tagging and partial veto –Tags 5% of  background in IceCube for study via ~3 TeV showers hitting stations –All downward events E > 300 TeV with trajectories inside IceTop vetoed –Larger events falling outside also vetoed Calibration of angular resolution with tagged single  and  bundles Muon survey of IceCube

5. NSF 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 extra-galactic sources of high-energy neutrinos to extra-galactic CR

6. Large showers with E ~ 100-1000 PeV will clarify transition from galactic to extra-galactic cosmic rays. Showers triggering 4 stations give ~300 TeV threshold for EAS array 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

7. NSF 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. NSF Baseline Review February 10-12, 2004 UW—Madison Jan 28, 2004T. Gaisser, L3 Lead for 1.3.2 IceTop8 IceTop Detector 2 m 1 m Diffusely reflecting liner

9. NSF 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 Two DOMs/tank gives redundancy against failure of any single DOM because only 1 low-gain detector is needed per station

10. NSF 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 (ideal) –Time of 1 st particle to < 10 ns –Implications for ice quality, tank lining

11. NSF 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 Fully integrated with in-ice DAQ

12. NSF 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 DOM LG DOM Tank 1 LG DOM HG DOM Tank 2 Station 1 Station 2 Station 80 DOM Hubs (10) IceTop Data Handler (IDH) Vert. Sh. Trigger........ Global Trigger InIce DATA InIce Trig.Gen. On line Hor. Sh. Trigger Common Event Builder DAQ Control Monitoring DOMs (320) 100 kB/s 32 MB/s 10 Hz

13. NSF Baseline Review February 10-12, 2004 UW—Madison Jan 28, 2004T. Gaisser, L3 Lead for 1.3.2 IceTop13 IceTop FPGA DateTaskResources 3/2002Proof of concept2001 test tank Altera dev. tools 11/2002Practical StudiesString 18 Data 2-5/2004Digital DesignUD: Bench test DOM UD: Test station Pole: 03/04 Tanks 5-8/2004ImplementationAltera dev. tools UD: bench & station 9/2004 - 1/2005 Integration w/in-ice FPGA & DOM App Development: support from DAQ (1.3.3). Testing: at UD High Trigger Rate + Bandwidth Constraints   : Advanced feature recognition e + e –  : 2-tank coincidence High Trigger Rate + Livetime concerns  2-level trigger, fast ATWD decision 10 ns timing + synchronous trigger  Advanced feature recognition Projection of muon waveform onto four basis functions & reconstruction. Projection of string-18 SPE waveform w/pedestal & reconstruction.

14. NSF Baseline Review February 10-12, 2004 UW—Madison Jan 28, 2004T. Gaisser, L3 Lead for 1.3.2 IceTop14 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 Trig. Trap calibration data Time Control DAQ Control

15. NSF Baseline Review February 10-12, 2004 UW—Madison Jan 28, 2004T. Gaisser, L3 Lead for 1.3.2 IceTop15 IceTop DAQ Development Pre-DAQ Design & Test FPGA IDH & Triggers Review Components Deliver algorithms/data formats/implementations IceTop DAQ v1 Initial Design Interface with In-Ice FPGA Implement and bench test SW – inc. IDH & Triggers Test at UD-station Assessment 8-31-2004 Requirements Acquire Test Data Digital design Design  Firmware Bench test FPGA Acquire DAQ Simulation SPE, muon, shower High Gain, Low Gain Coincidence logic UD Test } 4 months IceTop DAQ v1.1 Monitoring Calibration 5-31-2005 7-31-2005 IceTop DAQ v2 Design Review Build Test at UD-station Station test at Pole Array test at Pole 2-28-2006 In-Ice/IceTop Integrated DAQ CONUS tests Tests at Pole Acceptance Milestone 6-30-2006 PY-03 Pole-DAQ Requirements Modify In-Ice DAQ Test at UD-station Review (9-1-04) Install & Test Deliver 1-31-2005

16. NSF Baseline Review February 10-12, 2004 UW—Madison Jan 28, 2004T. Gaisser, L3 Lead for 1.3.2 IceTop16 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 (DOMs), 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 Maintain optical coupling of DOM to ice Meet environmental constraints of the DOM.

17. NSF Baseline Review February 10-12, 2004 UW—Madison Jan 28, 2004T. Gaisser, L3 Lead for 1.3.2 IceTop17 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

18. NSF Baseline Review February 10-12, 2004 UW—Madison Jan 28, 2004T. Gaisser, L3 Lead for 1.3.2 IceTop18 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 –Bottom-up requires cooling from bottom, DOMs freeze in at end –Top-down 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 plus additional protection from thermal cycling. –Achieve good ice quality but –Freeze time 60+ days > 40 days planned to allow 36 tanks/season in outyears –Temperature monitoring in place during winter to study thermal cycling 2003… Operation of test stations in lab for calibration, testing 2004 Construct and deploy 4 stations (8 tanks) in 04/05 season

19. NSF Baseline Review February 10-12, 2004 UW—Madison Jan 28, 2004T. Gaisser, L3 Lead for 1.3.2 IceTop19 2001 test tank Viewed by 2 AMANDA analog OMs Cloudy ice, asymmetric signals Currently taking data for comparison with station in lab Unsuitable as shower detector

20. NSF Baseline Review February 10-12, 2004 UW—Madison Jan 28, 2004T. Gaisser, L3 Lead for 1.3.2 IceTop20 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

21. NSF Baseline Review February 10-12, 2004 UW—Madison Jan 28, 2004T. Gaisser, L3 Lead for 1.3.2 IceTop21 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

22. NSF Baseline Review February 10-12, 2004 UW—Madison Jan 28, 2004T. Gaisser, L3 Lead for 1.3.2 IceTop22 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 Freeze time 60+ days – 40 days planned – mitigation options under study

23. NSF Baseline Review February 10-12, 2004 UW—Madison Jan 28, 2004T. Gaisser, L3 Lead for 1.3.2 IceTop23 Freeze-rate Current test tanks have insulated sides, bottom Plot shows ideal time profile of ice thickness (m) Increasing ice thickness slows freezing Conditions in field complicated and variable during freeze Wind speed Temperature Insulation partially removed Power outages Trial use of fans Evaluation, analysis & modeling of freeze now in progress

24. NSF Baseline Review February 10-12, 2004 UW—Madison Jan 28, 2004T. Gaisser, L3 Lead for 1.3.2 IceTop24 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.

25. NSF Baseline Review February 10-12, 2004 UW—Madison Jan 28, 2004T. Gaisser, L3 Lead for 1.3.2 IceTop25 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

26. NSF Baseline Review February 10-12, 2004 UW—Madison Jan 28, 2004T. Gaisser, L3 Lead for 1.3.2 IceTop26 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

27. NSF Baseline Review February 10-12, 2004 UW—Madison Jan 28, 2004T. Gaisser, L3 Lead for 1.3.2 IceTop27 Feb 10/11, 2004 Tank 9 with  telescope Tank 10

28. NSF Baseline Review February 10-12, 2004 UW—Madison Jan 28, 2004T. Gaisser, L3 Lead for 1.3.2 IceTop28 Muon signals from DOMs in Tank09 at South Pole

29. NSF Baseline Review February 10-12, 2004 UW—Madison Jan 28, 2004T. Gaisser, L3 Lead for 1.3.2 IceTop29 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 ?)

30. NSF Baseline Review February 10-12, 2004 UW—Madison Jan 28, 2004T. Gaisser, L3 Lead for 1.3.2 IceTop30 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 6/1/06

31. NSF Baseline Review February 10-12, 2004 UW—Madison Jan 28, 2004T. Gaisser, L3 Lead for 1.3.2 IceTop31 Simulations For tank design & calibration Of electronics and DAQ For station design For array response and trigger Of air showers –For array response and trigger –Coordinate with work under 1.4.3 for generation of background showers in deep detector

32. NSF Baseline Review February 10-12, 2004 UW—Madison Jan 28, 2004T. Gaisser, L3 Lead for 1.3.2 IceTop32 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.)

33. NSF Baseline Review February 10-12, 2004 UW—Madison Jan 28, 2004T. Gaisser, L3 Lead for 1.3.2 IceTop33 Initial calibration with SPASE SPASE will provide a tagged muon calibration and survey of first IceCube strings (before IceTop has enough detectors to reconstruct showers) SPASE will provide initial calibration of IceTop tanks 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) Sees IceCube strings from larger angle

34. NSF Baseline Review February 10-12, 2004 UW—Madison Jan 28, 2004T. Gaisser, L3 Lead for 1.3.2 IceTop34 “ WBS 1.3.2 IceTop” Cost Baseline (w/o escalation or contingency) WBS1.3.2.1 Tanks 1.3.2.2 Cables 1.3.2.3 DOMs 1.3.2.4 Engrng 1.3.2.5 SPASE 1.3.2.6 Mgmt Total Cost ($ K) 2,616 304 2242,676 4151,966 Labor1,305 304 2242,210 4151,209 Capital Equipment 1,283 0 0 255 0 0 Material & Supplies 28 0 0 211 0 63 Travel 0 0 0 0 0 693 Total WBS 1.3.2 Cost: $9.3 M Costs prior to PY3: $1.1 M

35. NSF Baseline Review February 10-12, 2004 UW—Madison Jan 28, 2004T. Gaisser, L3 Lead for 1.3.2 IceTop35 Fiscal Year04-0505-0607-0808-0909-1010-1111-1212-13Est. To Project Year345678910Complete Funding 1,6361,8441,6631,7097336178,202 US Contribution1,6361,8441,6631,7097336178,202 Non-US Contribution Budget Allocation US Collaborators: LBNL Univ. of Delaware UW-Madison UW-River Falls 31 1,511 44 51 70 1,686 37 51 1,575 37 51 1,643 34 31 667 34 31 556 30 31 101 7,638 218 245 Non-US Collaborators “WBS 1.3.2 IceTop” Funding Profile/Allocation ($K, w/o escalation or contingency) Prior to PY3 $1,100K Total Cost $9,302K

36. NSF Baseline Review February 10-12, 2004 UW—Madison Jan 28, 2004T. Gaisser, L3 Lead for 1.3.2 IceTop36 Fiscal Year04-0505-0607-0808-0909-1010-1111-1212-13Est. to Project Year345678910Complete Staffing On-board New Hires 8.9 6.9 2.0 9.4 8.4 1.0 8.4 7.1 4.5 3.9 41.9 Labor Category Senior Scientist Scientist Post Doc Grad Student Undergraduate Senior Manager Manager Senior Engineer Engineer Technician Administration 0.3 0.7 1.8 1.1 0.5 0 1.2 2.3 1 0.3 0.7 2.0 1.1 0.5 0 1.2 2.7 1 0.3 0.6 1.6 1.1 0.5 0 1.0 2.3 1 0.3 0.6 1.1 0.5 0 1.0 1.5 1 0.2 0.5 0.3 0.6 0.5 0 0.5 0.9 1 0.2 0.5 0.3 0.6 0.5 0 0.4 1 1.7 3.6 7.0 5.5 3.0 0 5.2 9.9 6.0 “WBS 1.3.2 IceTop” Staffing

37. NSF Baseline Review February 10-12, 2004 UW—Madison Jan 28, 2004T. Gaisser, L3 Lead for 1.3.2 IceTop37 Issues/Risks Mitigation of slow freeze time –Solution will ensure close-up on schedule –Two options are available Speed up freeze Design for freeze to finish after closing Final plan likely to include aspects of both Redesign underway based on extensive information from current season’s test Aggressive initial hardware schedule: –8 tanks in 04/05, 24 tanks in 05/06 How to implement transition of effort to data handling, detector verification (and operations) as construction progresses

38. NSF Baseline Review February 10-12, 2004 UW—Madison Jan 28, 2004T. Gaisser, L3 Lead for 1.3.2 IceTop38 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