Neutrino Physics - Lecture 4

Neutrino Physics - Lecture 4

Steve Elliott

LANL Staff Member

UNM Adjunct Professor

505-665-0068, elliotts@lanl.gov

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

Spring 2007 Steve Elliott, UNM Seminar Series

3

Cl Results

2.56 ± 0.16 ± 0.16 SNU

Expect7.5 SNU

Spring 2007 Steve Elliott, UNM Seminar Series

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

Spring 2007 Steve Elliott, UNM Seminar Series

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.

Spring 2007 Steve Elliott, UNM Seminar Series

6

Map to SAGE

Spring 2007 Steve Elliott, UNM Seminar Series

7

Baksan Valley, UG Laboratory

Spring 2007 Steve Elliott, UNM Seminar Series

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

Spring 2007 Steve Elliott, UNM Seminar Series

9

Reactor Layout

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

Spring 2007 Steve Elliott, UNM Seminar Series

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

Spring 2007 Steve Elliott, UNM Seminar Series

11

Proportional Counter Spectrum

Spring 2007 Steve Elliott, UNM Seminar Series

12

Results - Solar Rate

€

66.9−3.8, −3.2+3.9, +3.6 SNU

Expect128 SNU

Each run saw about 6 signalEvents.

Spring 2007 Steve Elliott, UNM Seminar Series

13

Gran Sasso

Italy:Not too far from Rome

Spring 2007 Steve Elliott, UNM Seminar Series

14

GNO Layout

Spring 2007 Steve Elliott, UNM Seminar Series

15

GALLEX Results

Expected128 SNU

Spring 2007 Steve Elliott, UNM Seminar Series

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

Spring 2007 Steve Elliott, UNM Seminar Series

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

Spring 2007 Steve Elliott, UNM Seminar Series

18

Photomultiplier Tubes

Spring 2007 Steve Elliott, UNM Seminar Series

19

SuperKamiokande Characteristics

• 50,000 t water

• 11,146 20” pmt

• 1,885 8” pmt

Spring 2007 Steve Elliott, UNM Seminar Series

20

SuperK Data

Spring 2007 Steve Elliott, UNM Seminar Series

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

Spring 2007 Steve Elliott, UNM Seminar Series

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

Spring 2007 Steve Elliott, UNM Seminar Series

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

Spring 2007 Steve Elliott, UNM Seminar Series

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

Spring 2007 Steve Elliott, UNM Seminar Series

25

An example Event: atmospheric neutrino

Spring 2007 Steve Elliott, UNM Seminar Series

26

SNO data

Radius of event vertex Angle with Sun

Spring 2007 Steve Elliott, UNM Seminar Series

27

Event Energy

Spring 2007 Steve Elliott, UNM Seminar Series

28

NC vs. CC