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

Jan 28, 2004 T. Gaisser, L3 Lead for 1.3.2 IceTop

1

NSF Baseline ReviewFebruary 10-12, 2004

IceTopTom Gaisser

Bartol Research Inst., Univ. of Delaware


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Hartill Baseline Review

February 10-12, 2004

UW—Madison

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/cm2) – 125 m spacing between IceTop stations – Ethreshold ~ 300 TeV for > 4 stations in coincidence– Useful rate to EeV


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UW—Madison

IceTop + IceCube: 1/3 km2 sr

Coverage to EeV energy


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UW—Madison

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


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UW—Madison

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


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UW—Madison

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, km2 EAS array with 125 m spacing


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UW—Madison

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 ~ 1018 eV to veto this background


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UW—Madison

IceTop Detector

2 m

0.9 m


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UW—Madison

Two DOMs: 10” PMTOne high-gain; one low-gain in each tank

To DAQ

IceCubeDrill Hole

~10-20 m

HG HG LGLG

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


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UW—Madison

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 1st particle to < 10 ns– Implications for ice quality, tank lining


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UW—Madison

DAQ design goals

• Feature recognition

• Low-gain / high-gain

• Local coincidence

• Horizontal showers

• Calibration mode


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UW—Madison

IceTop DAQ components

IceTopData

Handler

IceTopData

Handler

HG Chan

LG Chan.Tank 1

LG Chan

HG ChanTank 2

Station 1

Station 2

Station 80

DOM Hubs (10)

IceTopData

Handler(SP)

Vert. Sh. Trigger

.

.

.

.

GlobalTrigger

InIceDATA

InIceTrig.Gen.

On line

ICETOP DAQ

Hor. Sh. Trigger

CommonEvent Builder

DAQControl

MonitoringDOMs (320)

100 kB/s

32 MB/s

10 Hz


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UW—Madison

IDH and Trigger

Shower Trigger

Time Correction

CommonEvent Builder

GlobalTrigger

Hubs

Separate Monitor Data

Create stream for “station hits”

Create stream for “tank hits”

IceTopData Buffer

Post trigger data retrieval

Monitoring

Online

In-Ice Trigger

Horiz. Shower Trigger

Trap calibration data

Time Control

DAQControl

(IceTop Data Handler)


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UW—Madison

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.


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UW—Madison

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


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UW—Madison

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


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UW—Madison

2001 test tank

• Viewed by 2 AMANDA analog OMs

• Cloudy ice but reasonable signals

• Currently taking data for comparison with station in lab


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UW—Madison

Design of prototype tanks; 8 to be deployed in 04/05 with 1st 4 strings

Pallet

Insulated tank

DOM

Support structure for DOMS and cover

Freeze-control box*

Pressure relief system

Sunshade support*

*Removed after freeze


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UW—Madison

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


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UW—Madison

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


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UW—Madison

Cable runs looking toward MAPO away from SPASETank10 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.


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UW—Madison

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


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UW—Madison

4 IceCube DOMs now runningFrom: SMTP%"[email protected]" 15-JAN-2004 15:56:19.45To: [email protected]: First Four IceCube DOMs DeployedI'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


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UW—Madison

Schedule for tanks

PY3 PY4 PY5 PY6 PY7 PY8Strings deployed 4 12 16 18 18 12TanksDeployed: 8 24 32 36 36 24Manufactured: 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 ?)


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UW—Madison

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


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UW—Madison

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.)


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UW—Madison

Initial calibration with SPASE

• SPASE: 30 m gridthreshold ~ 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


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UW—Madison

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 cluster 180,000

• Total capital $1,564,867(+$60K)


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UW—Madison

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


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UW—Madison

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-timeScientists: UD:13 UW: 1 LBNL: 0 UWRF: 2Engrs, techs: UD: 5 UW: 1 LBNL: 2

• Labor cost by Project year (burdened, $ M)PY 3 4 5 6 7 81.22 1.27 1.13 0.91 0.56.

0.44

• Labor cost by WBS element ($ M)Tanks: $1.18 Cables: $0.30 DOMs: $0.22Engineering resources: $1.32 Detector Simulations: $1.02DAQ: $0.56 SPASE: $0.43 Management: $0.50

• Total Labor cost for 1.3.2: $5.53 M


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UW—Madison

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 88.3 6.9 4.4 3.8


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UW—Madison

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


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UW—Madison

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

Documents

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