March 19, 2010Kara Keeter1 Ultra-Sensitive Immersion Tank MOTIVATION –WHOLE-BODY COUNTING...

March 19, 2010 Kara Keeter 1

Ultra-Sensitive Immersion Tank

• MOTIVATION

– WHOLE-BODY COUNTING

– TARGET SENSITIVITIES TO 10-13 – 10-14 g/g U/Th, etc.

– POLLING OF ISE COLLABORATIONS

• MODEL: BOREXINO COUNTING TEST FACILITY

– CTF USED TO MEASURE BACKGROUND LEVELS IN LS


• COMPONENTS (BOREXINO CTF MODEL)

– LS INNER VESSEL – 2 m diam. sphere

– NYLON CONTAINMENT FOR INNER VESSEL

– PMTS (~100)

• Light concentrators, associated electronics, calibration system

– PMT SUPPORT STRUCTURE

• SS?

– WATER SURROUNDING PMTS? (OUTER VESSEL) - 4 m diam. cylinder?

• SS Containment for Outer Vessel

– ACCESS FROM TOP OR SIDE?



• COMPONENTS (MOST RECENT PLAN)

– LIQUID SCINTILLATOR – 4 m. diam. X 4 m. high cylinder

– Containment – SS?

– ACCESS FROM TOP

– PMTS (~100)

• Light guides/reflectors, associated electronics, calibration system

– PMT SUPPORT STRUCTURE

• SS?



• CONSIDERATIONS

– ACCESS FROM TOP OR SIDE

• Top access is easier if there is room (crane vs. rails)

• Nylon for container/wall?

• N2 cover gas?

– Geometry – inner/outer vessel, or one vessel?

• Locate PMTs as far from center as possible, to shield from PMT and PSUP background

• Borexino CTF has PMTs at 3.3 m from center (2.3 m from nylon wall)

• Possibly incorporate part of water shield, i.e. in corner

• Possibly use event reconstruction to determine events originating within fiducial volume?



• CONSIDERATIONS

– WILL NEED PURIFICATION SYSTEM FOR LS

• IF ULTRA-PURE WATER IS USED, WILL NEED TWO SYSTEMS

– WILL NEED CHILLER FOR COOLING FOR PMTS?

– N2 COVER GAS SYSTEM

– RADON LEACHING?

– IF THE ROOM DOESN’T HAVE AN ACTIVE MUON VETO THEN CONSIDER ONE JUST FOR IMMERSION TANK, OR PUT SOME PMTS AT BOTTOM (CTF HAS 20)



• CONSIDERATIONS

– CHOICE OF LS (PC+PPO? LAB+PPO? etc.)

– CHOICE AND PLACEMENT OF PMTS (~100 - 120)

• LIGHT CONCENTRATORS, ASSOCIATED ELECTRONICS, CALIBRATION SYSTEM

• CTF OPTIMUM WAVELENGTH ~ 390 nm



• COSTS

– FOR FIRST APPROXIMATION, ASSUME BOREXINO CTF AS MODEL

• 2-m diam. INNER VESSEL W/ LS AND NYLON CONTAINMENT

– VOLUME = 4.2 m3 = 4200 L = 1,100 gal

– Unpurified: Approx. 21 barrels @ $500 / barrel of LAB = $10,500

• 4-m diam. x 4-m high cylinder (MOST RECENT DESIGN)

– Volume = 50 m2 = 50,300 L = 13,300 gal

– Approx. 240 barrels @ $500 / barrel of LAB = $121,000



• COSTS

• PMTS (~100 - 120)

– $50 k - $200 k, depending on choice

– Light concentrators, associated electronics, calibration system

– CTF: 120 PM channels @ $2800 each = $336,000

• IN ULTRAPURE WATER (CTF MODEL)

– Ag-coated light concentrators @ ~$330 each = $40,000

• IN LS (MOST RECENT DESIGN)

– Al-coated light concentrators @ $140 each = $17,000



• COSTS

– 4-m diam. SS Outer Vessel w/ access port

– SS PSUP

– Purification plant(s)

– Chiller, cover gas, etc.



• STUDIES NEEDED

– CHOICE OF LS CHOICE OF PMT

– INNER/OUTER VESSELS VS. ONE VESSEL

– EVENT RECONSTRUCTION, FIDUCIAL AREA, PLACEMENT OF PMTS

– ETC.


March 19, 2010Kara Keeter1 Ultra-Sensitive Immersion Tank MOTIVATION –WHOLE-BODY COUNTING...

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