CUORE LNGS Review, November 2008 Karsten Heeger, Univ. Wisconsin 1

Calibration Slides for the CUORE Review at LNGS

CUORE LNGS Review, November 2008 Karsten Heeger, Univ. Wisconsin 2

Detector Calibration System

vertica

l cross se

ction o

f the cry

osta

t

Pb shield

300K

40K

4K

0.7K80mK

10mK

detectors@ ~10mK

Pb shield

motion system:insertion and extraction of sources in and out of cryostat

Source Deployment in between crystal towers to allow calibration of all bolometers

guide tubes: no straight vertical access

source strings:move under own weight in guide tubes

top view of detector array with source positions

source locations

CUORE LNGS Review, November 2008 Karsten Heeger, Univ. Wisconsin 3

Detector Calibration System

Motion Box and Drive Spool System

load cell

vacuum feedthrough with shaft

vacuum flange

motor

electrical feedthrough

narrow spool for spiral winding

guide pulley

drive spools can be removed for individual source exchange

~1m

guide tubes

detectors

motion box

CUORE LNGS Review, November 2008 Karsten Heeger, Univ. Wisconsin 4

Detector Calibration System

radioactive source wire• 56Co: proton activated Fe wire• 232Th: Thoriated Tungsten wire

Kevlar string

Cu crimp

PTFE heat shrink

source wire• flexible, moves in guide

tube under own weight

• small mass: < 5 grams

• vertical distribution of source activity can be adjusted

Source String

Guide Tubes

• stainless and/or machined from solid, low-background copper

~1m

~10mm

CUORE LNGS Review, November 2008 Karsten Heeger, Univ. Wisconsin 5

Calibration System: Cryogenic ChallengesCalibration System: Cryogenic Challenges

• Calibration system must be integrated with complex detector cryostat

• Must meet available cooling power requirements at all thermal stages

300K

40K

4K

0.7K

80mK

10mKStage T [K] Calibration system cooling

power budget [W]

40K 40 – 50 ~ 1

IVC 4 – 5 0.3

STILL 0.6 – 0.9 0.55m

HEX 0.05 – 0.1 1.1μ

MC 0.01 1.2μ

TSP 0.01 < 1μ

guide tubes

bolometric detectors

→ Cooldown of source string→ Friction heat during insertion/extraction→ Static heat load of guide tubes: thermal conductance&radiation emission

lead shield

lead shield

CUORE LNGS Review, November 2008 Karsten Heeger, Univ. Wisconsin 6

Detector Calibration SystemDetector Calibration System

Radioactive Sources: 56Co and/or 232Th, both have been used in Cuoricino

Schedule

–Q4/2008: review of preliminary design of calibration system

–Q1-Q3/2009: cryogenic tests of prototype source system with guide tube section at Wisconsin

–Q4/2009: installation of 2 full-scale prototype guide tube routings in the CUORE cryostat at LNGS; tests at 300K and < 4K.

–2010: installation and commissioning of the calibration system in the CUORE cryostat

Simulations

~100 events over background per peak are required for successful calibration

CUORE LNGS Review, November 2008 Karsten Heeger, Univ. Wisconsin 77