Neutrino Physics - Lecture 4 Steve Elliott LANL Staff Member UNM Adjunct Professor 505-665-0068, [email protected]

Neutrino Physics - Lecture 4

Steve Elliott

LANL Staff Member

UNM Adjunct Professor

505-665-0068, [email protected]

Spring 2007 Steve Elliott, UNM Seminar Series

2

Lecture 4 Outline

• Neutrinos from the SunThe neutrinos

Past experiments

What we know and what we want to learn


3

Cl Results

2.56 ± 0.16 ± 0.16 SNU

Expect7.5 SNU


4

SAGE and Gallex (GNO)

• 71Ga(e,e)71Ge

• 71Ge has 11.4 day half life.

• Expose Ga to neutrinos

• Extract Ge and count via its decay

• Decays of 71Ge are by electron capture: the signature is the 1.2 or 10.4 keV x rays, Auger electrons


5

SAGE Operations

1. Add carrier to Ga.2. After about 3-4 weeks, extract

Ge carrier and solar neutrino induced Ge.

3. Synthesize counter gas and fill proportional counter.

4. Count sample for about 6 months.


6

Map to SAGE


7

Baksan Valley, UG Laboratory


8

Source Calibration

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

92.4% enriched in 50Cr512.7 g of CrIrradiated for ~3 mnths517 kCi activity


9

Reactor Layout

10 reactorsEach can hold 8 tons of GaKept warm so Ga is liquid


10

Proportional Counters

• R: recombination• IC: ionization

chamber• PC: proportional

chamber• GC: Geiger counter• D: continuous

discharge

R

IC

PC

GC

D

Voltage

Co

llec

ted

Io

ns


11

Proportional Counter Spectrum


12

Results - Solar Rate

€

66.9−3.8, −3.2+3.9, +3.6 SNU

Expect128 SNU

Each run saw about 6 signalEvents.


13

Gran Sasso

Italy:Not too far from Rome


14

GNO Layout


15

GALLEX Results

Expected128 SNU


16

Kamiokande & SuperK

• Elastic scattering of e-

in a large water detector

• Mostly sensitive to e because CC cross section is about 6x higher than NC


17

Cherenkov Radiation

“Electrons in the atoms of the medium will be displaced and polarized by the passing EM field of a charged particle. Photons are emitted as an insulator's electrons restore themselves to equalibrium after the disruption has passed. (In a conductor, the EM disruption can be restored without emitting a photon.) In normal circumstances, these photons destructively interfere with each other and no radiation is detected. However, when the disruption travels faster than the photons themselves travel, the photons constructively interfere and intensify the observed radiation.”

Wikipedia

€

cosθ =1nβ


18

Photomultiplier Tubes


19

SuperKamiokande Characteristics

• 50,000 t water

• 11,146 20” pmt

• 1,885 8” pmt


20

SuperK Data


21

SNO

• ES, CC, and NC

• CC: d(e, pp)e-

– Sensitive only to e

• NC: d(x, np)x

– Sensitive to all x

• NC/CC ratio


22

SNO’s Location

< 100 /day102

103

104

105

106

107

Muon flux (m

-2 y

-1)

8000600040002000Depth Underground (ft)

IMB

Soudan

Kamioka

Gran Sasso

Frejus, Baksan, Homestake Mont Blanc

Sudbury

Kolar


23

The SNO Detector

9438 inward & 91 outwardWith concentrators = 54% coverage

Control room

Vectransupportropes

Urylon liner

5300 tonneslight water

1000 tonnesheavy water 1700 tonnes

light water

2039 m to surface1011 m to Sun

12 m diameteracrylic vessel

Support structure for 9500 PMTs,concentrators

Norite rock


24

SNO Calibration

Electronics CalibrationsBuilt-in programmable pulsers

Optical CalibrationsLaser ball: attenuation, scattering, reflectivity

Energy Calibrations16N source: 16O(n,p)16N*

-tagged 6.1-MeV source8Li Source: e- spectrum similar to 8B252Cf source: fission neutron source

Encapsulated U/Th source (low-E ’s)3H(p, )4He: 19.8-MeV Triggered U: Th sources (low-E ’s)

Michel electrons


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An example Event: atmospheric neutrino


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SNO data

Radius of event vertex Angle with Sun


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Event Energy


28

NC vs. CC

Documents

Neutrino Physics - Lecture 4 Steve Elliott LANL Staff Member UNM Adjunct Professor 505-665-0068, [email protected]