Nov 30, 2003 Tom Gaisser

The IceTop component of IceCube

Perspective from the South Pole

Nov 30, 2003 Tom Gaisser

Outline

• Scientific goals

• Design

• IceTop sub-group: tasks and staffing

• Budget & schedule

• Status of test-tank deployment, 03/04 season

• Lessons from current season

Nov 30, 2003 Tom Gaisser

IceTop:the surface component of IceCube

• 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

Nov 30, 2003 Tom Gaisser

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.

Nov 30, 2003 Tom Gaisser

IceTop station schematic

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

To DAQ

IceCubeDrill Hole

~10-20 m

HG HG LGLG

Two Ice Tanks 3.1 m2 x 1 m deep (a la Haverah, Auger)• 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

Tank simulation with GEANT-4

Nov 30, 2003 Tom Gaisser

IceTop tasks & activities• Design and construct tank detectors

– Evenson, Shulman, McDermott, Roth, Stoyan, technician (TBH)• Deploy tanks

– Gaisser, McDermott, Roth, technician (TBH) Yoshida (Chiba), student (UWRF), RPSC support, Engineer (SSEC)

• Confirm dynamic range scheme for 2 DOMs– Bai

• Calibrate detectors– Bai, Stoyan, Gaisser, Clem, Niessen, Spiczak (UWRF)

• Develop and install DAQ firmware– Evenson, Seckel

• Integrate DAQ software as part of IceCube– Seckel, Software engineer (TBH), Svarnkar (grad student), Asst Prof (TBH)

• Simulations– Stanev, Niessen, Gaisser

• Reconstruction, data handling– Tilav, Post-doc (TBH)

• Physics analysis– All, including Asst Prof (TBH)

Nov 30, 2003 Tom Gaisser

Staffing plans

• Current – 9 months faculty salary (includes 1 month UWRF)– 10 months technical staff– 5 months engineer– 50 months research scientists/post-doctoral (includes SPASE,

which becomes part of IceCube in PY3)– 12 months grad student

• Additional for PY03-PY10– 4 months faculty salary (new Asst Prof)– 12 months entry-level technician– 12 months software engineer– 12 months post-doc for event reconstruction– 12 months for second grad student

Nov 30, 2003 Tom Gaisser

Budget• IceTop (1.3.2) is an integral part of IceCube• IceTop effort focused at Bartol/UD & UWRF

– Air showers generate the primary background for IceCube as a neutrino telescope

– Bartol/IceTop efforts (e.g. in simulation, DAQ, reconstruction, physics analysis) make substantial contributions to other WBS elements

– 1.3.2 PY3: UD $1,086K; UWRF $60K; Total $1,146K– Other WBS elements in PY3: UD: $344K

• Tank construction schedule:– 10+32 in PY3 then 32 each in PY4,5,6 then 22 in PY7– This schedule allows shipping by vessel after PY3

Nov 30, 2003 Tom Gaisser

Outline of Bartol/UD budget PY3 Labor Capital Material & Supplies

(includes shipping)1.2.3.3 Field season ops $38K $20K

1.3.2.1 Tanks (10 + 32) 84 $250K 301.3.2.2 Cables (local coin only) 22 20 31.3.2.3 DOMs (labor only) 281.3.2.4 IceTop specific engineering 328 1201.3.2.5 Integration of SPASE 90 101.3.2.6 Management/office 101

1.3.4.5 Test DAQ System 361.3.4.6 First deployment DAQ 8

1.4.3.1 Event generation 39 101.4.3.3 Detector simulation 33 6

1.5.1 Detector verification 501.5.2.1 Reconstruction 781.5.3.2 Calibration 26

Totals 961 296 173 $1,436K

Nov 30, 2003 Tom Gaisser

South Pole 03/04 season

SPASE counting house

Nov 30, 2003 Tom Gaisser

100 m

Location of two test tanks, Nov ‘03

Nov 30, 2003 Tom Gaisser

Construction of tanks

• 2 Tanks delivered to Bartol in July; plumbing assembled

• Tanks & plumbing integrated, palletized and foamed at factory in VA late August

• Tanks arrive at Pt. Hueneme Sept 2

Nov 30, 2003 Tom Gaisser

Freeze-control equipment & DOMs

• Freeze control assembled at Bartol August - October

• Shipped with support equipment Sept-Oct (including sunshades)

• 4 DOMs with rev2 boards assembled, tested, shipped from UW October 31

Two views of freeze-control equipment mounted on tank inside sunshade at site

Nov 30, 2003 Tom Gaisser

Reassembly at South Pole• Gaisser, McDermott, Roth

arrive at South Pole Nov 10

• Used half of 40’x15’ heated Jamesway #76 in construction/cargo area

• Uncrated and assembled tanks near Jamesway; location convenient to logistical support

• Time: 2 persons, 1.5 weeks

• DOMs arrive Nov 15

Nov 30, 2003 Tom Gaisser

Preparation of site

• In parallel with assembly– Locate & survey site– Excavating trenches: two

hours using bulldozer with 14’ blade Nov 18

– Trenches 15 ft wide by about 40 ft long

– Tanks separated by 10 m– Power cord from SPASE

supplied by RPSC Nov 19

Nov 30, 2003 Tom Gaisser

Transport to site

• Nov 19– Load tanks on sled

– pull across skiway to MAPO

– Forklift from MAPO to site

– Level bottom of trenches

– Set & level tanks

– 3-man RPSC crew took a total of 2 hours

Nov 30, 2003 Tom Gaisser

Install freeze-control & DOMs

• Tank10 (1.0 m ice)– Install freeze box

– Install ejection pipe

– Bring up software

– Install DOMs

– Nov 20-21

• Tank09 (0.9 m ice)– Same procedure

– Nov 25-26

Nov 30, 2003 Tom Gaisser

Fill tanks

• Tank10– Freeze up of hose on

first attempt (Nov 21)

– Successful fill Nov 22• 20 minutes to fill

• < 10 RPSC man hours for transport and filling

• Tank09– Filled Nov 26, very

smooth operation

Nov 30, 2003 Tom Gaisser

Monitor freezing

• Two days to freeze over– Frost-covered ice– Clear; wind 6-10 kts– T = -40 to -35 deg C– Ice-surface at -20 deg C

37 days to freeze 1 m• But Tank10 at 2/3 ideal rate• Will reduce heat tape, pump cycle

time, add fans to reduce freeze time

• Tank09: problems with temp sensors currently being addressed. No water ejected after 100 hours suggests slow leak. To be investigated. Ice appears good.

• Winter-over scientist will take over monitoring to bridge until arrival of next crew (J. Eisch, S. Yoshida)

Nov 30, 2003 Tom Gaisser

Remainder of season

• Dec 1-5: train winter-over scientist (J. Lackey) and address problems

• Dec 10-30: Monitoring continues – S. Yoshida, Dec 10-31; J. Eisch Dec 20-Jan 6

• Dec 29-Jan 20: Install DOM-DAQ– J. Kelley, A. Karle with Evenson & S. Tilav

• Jan 12-27: Close tank– P. Evenson, Jan 12-27

Nov 30, 2003 Tom Gaisser

Lessons so far

• Modularize equipment– “plug and play” design to reduce labor needs– Programmable Logic Control to streamline assembly and operation

• Should include temperature control of heat tape• Commercial OTS control units at each tank

– See memo of Andrew McDermott based on experience this season• Manufacturing schedule should be at least one season ahead to allow

shipping by vessel• Need full Jamesway (40 x 15 ft) for staging• Begin early in season with tank assembly• Counting house, surface cables required early to allow setting tanks• Tanks to be filled as soon as Rodriquez well for drilling is ready—should

not wait to be filled as each hole is drilled.