Sources 1/2 Model 634 Deuterium source (side on, MgF2 window, 30 W) - - PowerPoint PPT Presentation

Sources 1/2

• Model 634 Deuterium source (side on,

MgF2 window, 30 W) for vacuum ultraviolet and UV range 115 to 300nm

Sources 2/2

• Model 621 universal chimney-type lamp housing with

forced air cooling, safety interlock, 150 W Xenon Arc Ozone free w/ rear reflector.

Source coupler

• Vacuum energy optimizer with two source branches

Xe lamp (250-600 nm) D2 lamp (115-250 nm)

Filter wheel for order sorting

Vacuum manual filter wheel with 5-posn, 25mm DIA:

• Long pass filter for 220nm
• Long pass filter for 400nm
• Open
• Block (for detector background)

Collimator coupling monochromator to sample chamber

• Compact collimating chamber

employs aspheric mirrors to produce a collimated beam. Provides 90% of the available rays emitted from monochromator at the sample (in Model 121.) Vacuum NW40K ports

Exit slit

Vacuum Sample Chamber

• Model 121 Reflectance /

Transmission sample chamber

• three-sample stage (sample,

reference, blank) indexing between 1" samples

• Quik-flange type ports (NW100K

and three NW40K)

• Measure variable angle reflectance

at incident angles from <10 – 60 degrees plus transmission (180 degrees.) Freely position sample and detector angle with respect to the incident beam.

Detector 2/2

28mm(1–1/8 Inch) Diameter, 11–stage, Bialkali Photocathode, Head–On Type, Low Dark Current, High Stability,Low Profile (R6094)

GENERAL

Parameter Description/Value Unit Spectral Response 300 to 650 nm Wavelength of Maximum Response 420 nm Photocathode MateriaI Bialkali Structure Number of Stages Minimum Effective Area 25 mm dia. Window MateriaI Borosilicate glass Dynode Base Suitable Socket Box and Line 11 14–pin glass base E678–14C (supplied)

PHOTOMULTlPLlER TUBES

R6094, R6095

TPMHB0223EA

200 800 600 400 0.01 0.1 1 10 100 CATHODE RADIANT SENSITIVITY (mA / W) QUANTUM EFFICIENCY (%) WAVELENGTH (nm) QUANTUM EFFICIENCY CATHODE RADIANT SENSITIVITY

Scintillator for VUV Detection

Sodium salicylate is the most popular scintillator we use today. Sodium salicylate has excellent fluorescent efficiency, nearly constant response in the 30 to 300nm spectral region, is easy to prepare, and does not affect vacuum pressure. Stability of fluorescence efficiency is excellent over time in vacuum systems with clean dry vacuum pumps. We have systems in the field using it for more than twenty years with continued good

• peration. It is our first choice for preparing photomultipliers for spectroscopy in the vacuum ultraviolet.

Emission Wavelength: 420nm Decay Time: 7-12 nanoseconds Characteristic: Crystalline layer of approximately 1-2mg/cm2 Fluorescence Efficiency: ~60% for incident wavelengths 40 to 300nm

115-250 nm

200-360 nm

350-600 nm

Composite ratio

Hematite

Lamp drift characterization

• Ratio of two lamp

spectra, obtained before and after the sample spectrum.

• Separation in time ~30

min

Lyot, 1929

Lunar Polarization

Moon Volcanic Ash

Mare Highlands

“per mille” or “per thousand” symbol

1971, Dollfus & Bowell

14

128

Bo

eo 120 160

LBO

Angle of vision in degrees A-Mixture of ashes, of 0.13 albedo

B -Average curve for the Moon

Figure 51. Lunar Ground and Volcanic Ashes area is 0.13. This number represents fairly well the average albedo

• f the Moon according to the

definition employed in the present work (1). The curve B of Fig. 51 is the average of the curvesfor the first quarter and the last quarter

• f the Moon. The

similarity between the curves A and B is remarkable, considering the great dif- ferences that the curves

• f other

materials show. On the

• ther

hand, the volcanic ashes scatter back in the direction of the source, even for very high angles

• f incidence, a proportion of polar-

ized light which is smaller than that of all the other substances studied. This proportion never 'exceeds the ratio of 1/1000. I have shown (French page

46) however,

that the Moon shows this effect

• nly

very faintly. Finally, the lunar ground, when

• bliquely

illuminated, scatters much more light in the direction close to the Sun than in the opposite direction. The

same is true of an

area covered with dull powders and especially with volcanic ashes. All these similarities lead us to conclude that the Moon must be almost completely covered with powders having a constitution similar to that of the Earth's volcanic ashes. These powders could also be in the form of a very

(1)

The value of this quantity is poorly known. Zollner gave the value

• f 0.17, the

Annuaire du Bureau des Longitudes gives the value

• f 0.15, the work entitled Astronomy by Russel, Dugan

and Stewart gives for the most probable average value for the brightness of the full Moon a value

• f 1/465,000 with respect to the Sun (from this ratio a value of 0.110 is found

for the albedo).

Accessible with LASP TREX lab Roughly: 10 – 100deg (exact range TBD)

Vacuum pumpdown curve

Cooled sample holder

• Liquid Nitrogen cryostat (Janis

VPF-100)

• Temperature controller with

cable (Lakeshore 325)

Vacuum pump

• 300 liter per second air-cooled

turbo pump system (Edwards) with adapter from pump to spectrometer, pump PS and controller, oil free scroll roughing pump, metal fore line to connect the two. Included gauge system with digital display and includes integrated controller

• Manifold on pump connected to

spectrograph cavity and sample chamber (i.e. bypassing exit slit)

Lunar polarization

1970, Coyne & Pellicori

Coyne GV, Pellicori SF (1970) Wavelength dependence of polarization. xx. the integrated disk of the moon. Astron J. 75:54-60. doi:10.1086/110940

Polarization vs wavelength

200 300 400 500 wavelength (nm) 0.00 0.05 0.10 0.15 0.20 0.25 polarization WUPPE (not full disk) [8] SOLSTICE Coyne & Pellicori [7] waning waxing

Fox et al, 1998, WUPPE, MNRAS 298 Coyne & Pellicori, 1970, Astron. J. 75 60° phase

21