1. Nebraska’s Statewide Outreach and Education Experiment The Cosmic Ray Observatory Project Dan Claes University of Nebraska-Lincoln Washington Area Large Time-coincidence Array Needles in a Haystack Neutrinos Among The Cosmic Rays The Henderson Mine Project Tuesday, September 28, 2004

2. Henri Becquerel (1852-1908) received the 1903 Nobel Prize in Physics for the discovery of natural radioactivity. Wrapped photographic plate showed clear silhouettes, when developed, of the uranium salt samples stored atop it. 1896 While studying the photographic images of various fluorescent & phosphorescent materials, Becquerel finds potassium-uranyl sulfate spontaneously emits radiation capable of penetrating  thick opaque black paper  aluminum plates  copper plates Exhibited by all known compounds of uranium (phosphorescent or not) and metallic uranium itself.

3. In ordinary photographic applications light produces spots of submicroscopic silver grains a fast charged particle can leave a trail of individual Ag grains 1/1000 mm (1/25000 in) diameter grains plates coated with thick emulsions (gelatins carrying silver bromide crystals) clearly trace the tracks of charged particles

4. 1898 Marie Curie discovers thorium ( 90 Th) Together Pierre and Marie Curie discover polonium ( 84 Po) and radium ( 88 Ra) 1899 Ernest Rutherford identifies 2 distinct kinds of rays emitted by uranium  - highly ionizing, but completely absorbed by 0.006 cm aluminum foil or a few cm of air  - less ionizing, but penetrate many meters of air or up to a cm of aluminum. 1900 P. Villard finds in addition to  rays, radium emits  - the least ionizing, but capable of penetrating many cm of lead, several feet of concrete

6. B-field points into page 1900-01 Studying the deflection of these rays in magnetic fields, Becquerel and the Curies establish  rays to be charged particles

7. 1900-01 Using the procedure developed by J.J. Thomson in 1887 Becquerel determined the ratio of charge q to mass m for  : q/m = 1.76×10 11 coulombs/kilogram identical to the electron!  : q/m = 4.8×10 7 coulombs/kilogram 4000 times smaller!

9. 1900 Charles T. R. Wilson’s ionization chamber Electroscopes eventually discharge even when all known causes are removed, i.e., even when electroscopes are sealed airtight flushed with dry, dust-free filtered air seemed to indicate an unknown radiation with greater penetrability than x-rays or radioactive  rays Speculating they might be extraterrestrial, Wilson ran underground tests at night in the Scottish railway, but observed no change in the discharging rate. far removed from any radioactive samples Also necessary to be shielded with 2 inches of lead But even when STILL slowly discharges!

10. 0 1909Jesuit priest, Father Thomas Wulf, developed an ionization chamber with a design planned specifically for high altitude balloon flights. A taut wire pair replaced the gold leaf. This basic design became the pocket dosimeter carried to record one’s total exposure to ionizing radiation.

11. Hess lands following a historic 5,300 meter flight. August 7, 1912 National Geographic photograph 1911-12 Austrian physicist Victor Hess, of the Vienna University, and 2 assistants, carried Wulf ionization chambers up in a series of hydrogen balloon flights. taking ~hour long readings at several altitudes both ascending and descending radiation more intense above 150 meters than at sea level intensity doubled between 1000 m to 4000 m increased continuously through 5000 meters Dubbed this “high” level radiation Höhenstrahlung

12. 50  m Cosmic ray strikes a nucleus within a layer of photographic emulsion 1937 Marietta Blau and Herta Wambacher report “stars” of tracks resulting from cosmic ray collisions with nuclei within the emulsion

13. Before the explosion: v o = 0 m1m1 m2m2 v1v1 v2v2 After the explosion: Mass, M

14. With no external forces, P the momentum P must be conserved. P Initially: P = 0 Pvv Finally: P = m 1 v 1 + m 2 v 2 = 0 vv m 1 v 1 =  m 2 v 2 m1m1 m2m2 vv1vv1 vv2vv2 v o = 0

15. p = 0 p gas p rocket p i = 0 = p f p gas = – p rocket = p gas + p rocket p i = 0 = p f = p rifle + p bullet p rifle = – p bullet

16. A cannon rests on a railroad flatcar with a total mass of 1000 kg. When a 10 kg cannon ball is fired at a speed of 50 m/sec, as shown, what is the speed of the flatcar? A) 0 m/s B) ½ m/s to the right C) 1 m/s to the left D) 20 m/s to the right

17. A bomb at rest explodes into four fragments. The momentum vectors for three of the fragments are shown. Which arrow below best represents the momentum vector of the fourth fragment? ?

18.  - decay  - decay

19. Some Alpha Decay Energies and Half-lives Isotope KE  (MeV)  1/2 (sec -1 ) 232 Th4.011.4  10 10 y 1.6  10  18 238 U4.194.5  10 9 y 4.9  10  18 230 Th4.698.0  10 4 y 2.8  10  13 238 Pu5.5088 years 2.5  10  10 230 U5.8920.8 days 3.9  10  7 220 Rn6.2956 seconds 1.2  10  2 222 Ac7.01 5 seconds 0.14 216 Rn8.0545.0  sec 1.5  10  212 Po8.780.30  sec 2.3  10  216 Rn8.780.10  sec 6.9  10 

20. B Before decay: After decay: Potassium nucleus A 1930 Series of studies of nuclear beta decay, e.g., Potassium goes to calcium 19 K 40  20 Ca 40 Copper goes to zinc 29 Cu 64  30 Zn 64 Boron goes to carbon 5 B 12  6 C 12 Tritium goes to helium 1 H 3  2 He 3

21. 1932 Once the neutron was discovered, included the more fundamental n  p + e For simple 2-body decay, conservation of energy and momentum demand both the recoil of the nucleus and energy of the emitted electron be fixed (by the energy released through the loss of mass) to a single precise value. but this only seems to match the maximum value observed on a spectrum of beta ray energies! E e = (m A 2 - m B 2 + m e 2 )c 2 /2m A

22. No. of counts per unit energy range Electron kinetic energy in KeV 51015200 The beta decay spectrum of tritium ( H  He). Source: G.M.Lewis, Neutrinos (London: Wykeham, 1970), p.30)

23. 1932 n  p + e  + neutrino charge0 +1  1 ? mass 939.56563 938.27231 0.51099906 ? MeV MeV MeV neutrino mass < 5.1 eV < m e /100000  0

24. 1936 Millikan’s group shows at earth’s surface cosmic ray showers are dominated by electrons, gammas, and X-particles capable of penetrating deep underground (to lake bottom and deep tunnel experiments) and yielding isolated single cloud chamber tracks

25. 1953, 1956, 1959 Savannah River (1000-MWatt) Nuclear Reactor in South Carolina looked for the inverse of the process: n  p + e- + neutrino p + neutrino  n + e + Cowan & Reines with estimate flux of 5  10 13 neutrinos/cm 2 -sec observed 2-3 p + neutrino events/hour

26. Underground Neutrino Observatory The proposed next-generation underground water Čerenkov detector to probe physics beyond the sensitivity of the highly successful Super-Kamiokande detector in Japan

27. The SuperK detector is a water Čerenkov detector 40 m tall 40 m diameter stainless steel cylinder containing 50,000 metric tons of ultra pure water The detector is located 1 kilometer below Mt. Ikenoyama inside the Kamioka zinc mine.

28. The main sensitive region is 36 m high, 34 m in dia viewed by 11,146 inward facing Hamamatsu photomultiplier tubes surrounding 32.5 ktons of water

29. Underground Neutrino Observatory 650 kilotons active volume: 440 kilotons 20 times larger than Super-Kamiokande major components: photomultiplier tubes, excavation, water purification system. $500M The optimal detector depth to perform the full proposed scientific program of UNO  4000 meters-water-equivalent or deeper

30. Aspen High School, Aspen, CO Basalt High School, Basalt, CO Roaring Fork Valley High School, Carbondale, CO Lake County High School, Leadville, CO The highest-elevation school in U.S. -- 10,152 feet above sea level SALTA: Snowmass Area Large Time-Coincidence Array Empire Clear Creek High School, Empire, CO

31. Polishing scintillator edges outside Conference Center Making detectors light-tight SALTA Workshop, July 2001, Snowmass, CO mass phototube gluing

32. CROP article in Lincoln Journal Star, 7 August 2003

33. The Chicago Air Shower Array Located in the Utah Desert 1089 stations, 15m spacing covering 0.23 square km each houses 4 scintillators w/tubes 1 high and 1 low voltage supply CROP recycles retired detectors from the Chicago Air Shower Array

34. U.S. Army Photo September 30, 1999 The CROP team at Chicago Air Shower Array (CASA) site

35. CASA detectors’ new home at the University of Nebraska 2000 scintillator panels, 2000 PMTs, 500 low and power supplies at UNL

36. PMMA (polymethyl methacrylate) doped with a scintillating fluor Read out by 10 stage EMI 9256 photomultiplier tube Recycling material inherited from The Chicago Air Shower Array 2 ft x 2 ft x ½ inch

37. Leadville 1 10 miles

38. Henderson Mine Visit Dec 4, 2003 hosted by Chip deWolfe Marc Whitley Diana Kruis Nancy Spletzer Aspen High School Basalt High School Clear Creek High School Michelle Ernzen Laura French Lake County School Roaring Fork Valley Hans-Gerd Berns University of Washington Dan Claes University of Nebraska

39. Scouted 3 possible locations between 2800-3900 ft depths 110 power available

40. January 13-15 – SALTA students checked out condition of their detectors

41. Aspen Center for Physics July, 2004: Back for MORE!

42. Aspen Center for Physics Education & Outreach Workshop July 6-8 SALTA schools take over the library, setting up cosmic ray telescopes, for training in the new DAQcard that will facilitate all their data-taking.

43. ¼ in lead Detector Configuration requiring a coincidence in each pair helps cut down “noise” sandwiched with lead sheet Two modules each a pair of telescoped of detectors

44. At mining level (3000 mwe) any one (2 ft  2 ft) panel can be expected to count only a handful of events / day May need week(s) long runs We will move detectors at 2-3 week intervals

45. Desktop Base Station An ~identical pair of modules will run in a fixed location (surface office) to establish a baseline