An Aspect of Dark
NORMALLY Think Of
Even If It Wasn’t Frank
and Ettore’s Birthday
* Who do you think you’re kidding?
Think Cracks ∗
* Who hasn’t had problems with them?
First runs of
CRESST Cryogenic Dark Matter Detector
in Gran Sasso
Much careful eﬀort– Expect: few events/day
Horror–Find: 1000’s /hour
Several months, crazy hypotheses (touched with
hands? traﬃc in tunnel?...)
Even an unknown Background is Poisson in time
But not Poisson –come in ‘Bursts’– so not
Whaaaat the Devil is it?
Sapphire crystal surface, contact point with sapphire ball
Replace hard sapphire support balls
with softer plastic stubs
Rate goes down to expected level
Events were all “Cracks”
Several years later...early one morning (11:AM)...
We must have the worlds’ greatest collection of
Good energy, time measurement, low background
Tens-hundreds of thousands of events
Several years later... Finland ( 11:AM, Jyvaskala )
No. events per keV
1 10 100 1000
Energy spectra from four runs
Just like earthquakes,
Even about same power β ≈ 1.7 − 2.0
Except we really know energy, EQ’ers don’t.
Richter scale is an amplitude and with only small part of total energy.
But EQ data has much larger range
Many plots, correlations
no. events per unit w
1e-04 0.001 0.01 0.1
waiting time w in hrs
Upper:Cracks; Lower: Calibration photons
Photons: e−w/wo (Poisson)
Also found for earthquakes, about same power
α ≈ 0.3
• New Technology for Studying Microfracture
Unparalled sensitivity. Perhaps to few atom level with
Many 10x better than previous technology
• Striking parallels with EQ’s
Stupendous energy range! And big material diﬀerences
Something universal must be going on. Relations between
exponents, α, β?
• Absolute measurement of total energy
• Large clean data sets.
Look for patterns, “percursors” of ‘Big Events’ ?
(So far we couldn’t ﬁnd an eﬀective ’EQ predictor’ algorithm)
• Reference: ‘Fracture Processes Observed With A
Cryogenic Detector’, J.Astrom et al., arXiv:physics/0504151;
Phys. Lett.A356 262 (2006).
(Also arXiv:physics/061208, arXiv:0708.4315)
Mass Spectroscopy of
Or,... one of Leo’s
20 keV = 20 keV ! !
Usual detectors need velocity
In genomics, proteomics,..biologists will have
fragments in kiloDaltons (Dalton= 1 H atom)
accelerator ∼ 20keV .
Since E = 1 M v 2, molecule is slooow.
With practically all familiar detectors, initiating
event is hitting an electron.
This depends on velocity (max when
v(projectile) ≈ v(atomic electron)) and it becomes
diﬃcult and ineﬃcient for e.g.
Cryodetector needs energy (Heat)
For a cryodetector a huge, slow, 20 keV protein
is the same as a 20 keV electron !?
So ask (1991) Marvin ( brother microbiologist).
Marv to Leo: Maybe interesting
Discusions, ﬁnally actually carried out by
Damien Twerenbold et al.
We have since seen up to 100 000 Dalton proteins
Also very high sensitivity, good timing reduces
• For cryodetector really true that 20keV ≈ 20keV !
• In principle no mass limitation
• Very high sensitivy
Rare protein studies and diagnostics,...
• Good timing gives high mass resolution
Could see deuteration of single base?
• References: D. Twerenbold et al, Appl. Phys.
Lett. 68, 3503 (1996);
P. Christ et al. European Journal of Mass
Spectrometry 10, 469-476 (2004)