News in the
thermo-mechanical
measurement in the
Firenze facility
Gianpietro Cagnoli a,b), Enrico Campagna a,c),
Elisabetta Cesarini a), Matteo Lorenzini a), Giovanni Losurdo a),
Filippo Martelli a,c), Francesco Piergiovanni a,c), Flavio Vetrano a,c)
a)
b)
c)
INFN Sez. Firenze
University of Glasgow
University of Urbino
3rd ILIAS-GW Annual General Meeting, London October 26-27, 2006
1
Scientific activity of Firenze-Urbino
group in STREGA

Research lines in STREGA M5 task: “Characterization of
the losses of Si fibres at different temperatures, reaching the
Liquid Nitrogen temperature ”
 Measurement of Silicon fibres: first results published in
collaboration with the Pisa and Perugia INFN groups
RSI 77, 044502 (2006) & CQG 23, 5277 (2006)


Work in progress on thermomechanical characterization of
new materials
Facilities setup in Florence lab

Thermal conductance measurement facility


Q measurement facility


Results on Si and Silicate-bonding
Innovative nodal suspension, designed and realized
a measurement facility

Double FP cavity setup being completed
2
Facility for k – The cryostat
Vacuum chamber
Outer tank
Liquid N2
Inner tank
Liquid He
Outer cold shield
Inner cold shield
30 cm
Optical
windows
Experimental chamber
Optical windows
3
Facility for k
Measurements on a Si reed
BOX
HEATER
INSULATOR
CLAMP
THERMOMETERS
SAMPLE
SAMPLE
HEATER
COPPER
BOX
T  100 mK
P  Vi
L  5.8 cm
D  5 mm
L
kP
S  T
4
Facility for k
Measurements on a Si reed
 = 260 cm
10000
n  4 1013 cm-3
 =5000 cm
Th. conductivity (W/mK)
n  31012 cm-3
Our sample:
purity 10-6
  42 cm (measured)
1000
 =15-25 cm
n  51014 cm-3
Solid lines from Y.S. Touloukian, E.H. Buyco,
“Thermo-physical properties of matter”, Plenum, NY, 1970
100
0
50
100
150
200
T (K)
5
Facility for k - Si-bonded samples


1”ø x ¼ ” silicon
disks silicate bonded
by the Glasgow group
Work done in
collaboration between
Glasgow and Florence
Cold plate
Heat
sink
Sample
Heater
Thanks to G. Frossati for providing the PT1000 sensors
6
Facility for k - Si-bonded samples

Setup had been optimized for fibers and rods
Heat flux inhomogeneity problems
 2 PT1000 put on the lateral surface
 P=0.5 W  T=30 mK



Resolution around 500 mK
Bad data reproducibility

Not depending on



Power losses by radiative emission
PT1000 calibration
Hidden reason under investigation

Bad electrical contacts?
7
Facility for Q measurements
GeNS: a Gentle Nodal Suspension

Simple but innovative idea


Thickness < diameter  stable equilibrium
Advantages w.r.t. other methods

No clamp



Allows to test coated samples
Minimize the contact surface
Independent relevant parameter estimation



Disk-sphere friction
Surface roughness
Q-dependence on suspension centering
8
Facility for Q: GeNS at work



4.75 ø mm steel ball bearing
15 mm diameter contact
surface (estimated)
Optical lever readout
9
Facility for Q: measurements

Samples

HOQ300 fused silica 75 ø mm disks2.4 mrad wedge flamed
0.4 mrad wedge
5.E+06
0.4 mrad wedge flamed - a
1÷3 mm thickness
4.E+06
0.4 mrad wedge flamed - b
 Normal/special surface working (parallelism)
0.4 mrad wedge flamed - c
 Flamed/unflamed lateral surface

3.E+06
Q
1.5E+06
1.4 mrad wedge
1.7 mrad wedge
2.E+06
1.4 mrad wedge flamed
Q
1.0E+06
1.E+06
5.0E+05
0.E+00
0.0E+00
0
0

5000
1000
2000
3000
10000
4000
5000
6000
Frequency
[Hz]
frequency [Hz]
15000
7000
8000
9000
Q vs frequency (residual pressure ≈ 10e-5 mbar)
10
Facility for Q: measurements

Q versus vacuum chamber pressure
Measured Q in millions
40
f vs pressure (75mm x 1mm special disk)
y displacement [ mm]
1.E-05
30
f
3.9
20
4.0
4.0
0
1.E-07
-10
4.1
4.0
disk (measured)
air (Saulson '94)
-20
-40
-80
total
1.E-02
-60
P [mbar]-20
x displacement [ mm]
-40
4.0
0
1.E-01
20
Q versus suspension position


4.1
4.0
1.E-06
10
1.E-08
-30
1.E-03

3.9
1.3 mm displacement precision ( → 2mm on the target screen)
Reproducibility around 3% even after a month
11
Facility for small displacement
0.1 K
Heating wires for RC temperature control
1h


Fluctuation below 0.01 K needed
Few mK stability reached
12
Future work

Facility for k


Characterization of Si-bonding influence on the
thermal conductance
Facility for Q
Characterization of GeNS with measurement on
Suprasil 311
 Coated sample investigation


Facility for a

Complete setup
13