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TITLE. Precise measurement of air fluo yield. How? Control everything. b) Work with Gwenaelle. The bench. The cross. Electron beam. 90 Sr spectrum. Electron ADC (1 st threshold). Electron ADC (2 nd threshold). “Integral” PMT. The spectrometer. Entrance slit alignment. - PowerPoint PPT Presentation
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4th air fluo workshop Prague, 17-20 / 05 2006 P. Gorodetzky APC - Collège de France Paris
TITLE
Precise measurement of air fluo yieldHow?
a) Control everything
b) Work with Gwenaelle
4th air fluo workshop Prague, 17-20 / 05 2006 P. Gorodetzky APC - Collège de France Paris
The bench
4th air fluo workshop Prague, 17-20 / 05 2006 P. Gorodetzky APC - Collège de France Paris
4th air fluo workshop Prague, 17-20 / 05 2006 P. Gorodetzky APC - Collège de France Paris
The cross
4th air fluo workshop Prague, 17-20 / 05 2006 P. Gorodetzky APC - Collège de France Paris
Electron beam
4th air fluo workshop Prague, 17-20 / 05 2006 P. Gorodetzky APC - Collège de France Paris
90Sr spectrum
4th air fluo workshop Prague, 17-20 / 05 2006 P. Gorodetzky APC - Collège de France Paris
Electron ADC (1st threshold)
4th air fluo workshop Prague, 17-20 / 05 2006 P. Gorodetzky APC - Collège de France Paris
Electron ADC (2nd threshold)
4th air fluo workshop Prague, 17-20 / 05 2006 P. Gorodetzky APC - Collège de France Paris
“Integral” PMT
4th air fluo workshop Prague, 17-20 / 05 2006 P. Gorodetzky APC - Collège de France Paris
The spectrometer
4th air fluo workshop Prague, 17-20 / 05 2006 P. Gorodetzky APC - Collège de France Paris
Entrance slit alignment
4th air fluo workshop Prague, 17-20 / 05 2006 P. Gorodetzky APC - Collège de France Paris
Why a spectrometer?
Here, we respect the Numerical Aperture
Filter properties vary with incident angle
4th air fluo workshop Prague, 17-20 / 05 2006 P. Gorodetzky APC - Collège de France Paris
PMT window
===> Silica
4th air fluo workshop Prague, 17-20 / 05 2006 P. Gorodetzky APC - Collège de France Paris
Gas
Very cleanNo argon
∆P/P ~ 0.1%
Flow = 1 l/h
4th air fluo workshop Prague, 17-20 / 05 2006 P. Gorodetzky APC - Collège de France Paris
Daq
4th air fluo workshop Prague, 17-20 / 05 2006 P. Gorodetzky APC - Collège de France Paris
Photon spectrum (single pe)
4th air fluo workshop Prague, 17-20 / 05 2006 P. Gorodetzky APC - Collège de France Paris
TDC spectrum
Atmospheric pressure
4th air fluo workshop Prague, 17-20 / 05 2006 P. Gorodetzky APC - Collège de France Paris
Discriminators dead-time
4th air fluo workshop Prague, 17-20 / 05 2006 P. Gorodetzky APC - Collège de France Paris
dE/dx
4th air fluo workshop Prague, 17-20 / 05 2006 P. Gorodetzky APC - Collège de France Paris
Fluo yield ε = Nphotons
/ Lelectrons
How many Photoelectrons ? How many Photons ?
Electrons travel?
Analysis
4th air fluo workshop Prague, 17-20 / 05 2006 P. Gorodetzky APC - Collège de France Paris
dE/dx
4th air fluo workshop Prague, 17-20 / 05 2006 P. Gorodetzky APC - Collège de France Paris
How many Photoelectrons ?
a) Région C : N(S+B)
b) NB on the same interval
c) NS = N
(S+B) - N
B
d) Ns / N
histo = N
pe / N
coïnc
4th air fluo workshop Prague, 17-20 / 05 2006 P. Gorodetzky APC - Collège de France Paris
Discriminator cut
PMT-2020 : + 3.76 %PMT-JY : + 3.85 %
Pressure and temperature
Measured inside and outside the chamber. Values sent to a slow 2048 channels ADCAround 760 mm Hg and 22°, channels # around 1000Variations in a run: typically 1 channel
4th air fluo workshop Prague, 17-20 / 05 2006 P. Gorodetzky APC - Collège de France Paris
Analysis
- P: number of counts in TDC peak-T: integral of TDC spectrum-C: number of coinc (scaler)-D: discri cut-Ne: :Electrons that reached the scintillator (scaler)-TM: dead time of scaler-Lmoy :travel of electrons = 46.11 ± 0.2 mm -ePMT :absolute efficiency of PMT = 0.178 ± 0.004-Tquartz: transmission of silica window = 0.992 ± 0.003-Egeo: geometrical efficiency (3.689 ± 0.02)10-4
4th air fluo workshop Prague, 17-20 / 05 2006 P. Gorodetzky APC - Collège de France Paris
Results
With our temp and pressure:
3.86 ± 0.09 ph / m for Ee = 1.19 MeV P = 753.8 mm Hg, T = 295.95 K
3.87 ± 0.09 ph / m for Ee = 1.54 MeV P= 751.8 mm Hg, T = 296.05 K
a) to normalize to 0.85 MeV,we use dE/dx
4th air fluo workshop Prague, 17-20 / 05 2006 P. Gorodetzky APC - Collège de France Paris
Theoretical normalization
b) To normalize to US standard P and T
4th air fluo workshop Prague, 17-20 / 05 2006 P. Gorodetzky APC - Collège de France Paris
Bianca
4th air fluo workshop Prague, 17-20 / 05 2006 P. Gorodetzky APC - Collège de France Paris
Normalized results [300-430 nm]
Our results, normalized to 0.85 MeV, and US standard conditions
3.945 ± 0.120 photons / meter
4th air fluo workshop Prague, 17-20 / 05 2006 P. Gorodetzky APC - Collège de France Paris
Nitrogen to air ratio
4.90 ± 0.01
OK with Nagano (thanks to his error bars)Excludes Davidson & O’Neil
4th air fluo workshop Prague, 17-20 / 05 2006 P. Gorodetzky APC - Collège de France Paris
Spectrometer resolution
With a He-Ne laser
4th air fluo workshop Prague, 17-20 / 05 2006 P. Gorodetzky APC - Collège de France Paris
Spectrometer calibration
Not betterthan 20%
4th air fluo workshop Prague, 17-20 / 05 2006 P. Gorodetzky APC - Collège de France Paris
The lines
Ulrich
Inte
nsity
(ar
b. u
nits
)In
tens
ity (
arb.
uni
ts)
Our work with6 nm FWHM
4th air fluo workshop Prague, 17-20 / 05 2006 P. Gorodetzky APC - Collège de France Paris
Conclusion (preliminary)
If HiRes took Kakimoto 1.4 MeV==> their showers are now~ 20% lower in energy than published
It does not go along Bahcall and Waxman explanationJ.N. Bahcall and E. Waxman (hep-ph/0206217 v5 27 Feb 2003)
