1. Latest results from the superfluid-helium UCN source SUN2 at ILL
« All along the conference we will see presentations of experiments using Ultra-cold neutons, and their interests for fundamental physics. But production of these UCNs is still a research field. I will present here developements and results done at ILL on a new Source of Ultra-cold neutrons (SUN2) using Superfluid Helium.»
Florian MARTIN
ILL, Grenoble

2. New Source of Ultracold Neutrons
Physical Principle:
8.9 A Neutron Downscattering  Single phonon excitation in LHe
No nuclear absorption loss for neutrons  High UCNs densities can be achieved (~ few 100 UCNs/cm3 )
(Golub et al. Physics letter 62A, 337 (1977) )
-Dedicated beam ILL : H172B
-Experiments goal:
High UCNs densities > 100 UCNs/cm3
Test of differents configurations (cold guide, extraction system,…)
UCNs Extraction to room temperature  For room temperature experiments (Cf O.Zimmer presentation on Thursday)
Increase size of character
Remove monochromator
09-Sept-2013
F.Martin Latests results

3. Cold Neutron Beam Dedicated position, shared beam
Primary beam secondary beam
First/second order bragg peaks
Improve transition from previous slide
Dedicated position, shared beam
a 8x8 cm2 homogeneous beam
flux ~108
09-Sept-2013
F.Martin Latests results

4. Source preparation UCN production vs Temperature
Liquid Helium Source Filling
UCN production
vs Temperature
First hand change of the gif then gif remove points on the filling graph
09-Sept-2013
F.Martin Latests results

5. Density measurements Experiment: RESULTS - UCN accumulation for 300s
- turn off beam
- count UCNs
RESULTS
Temperature is 630 mK
Number of UCNs counted :
with fit extrapolation :
Source volume: 4l  ~120 UCNs/cm3
Number of UCNs whithout the fit, calculated errors
09-Sept-2013
F.Martin Latests results

6. Storage time constants
Experiment :
UCN accumulation for 300s
then turn off beam
wait for a delay time
count UCNs
RESULTS
Fit of decay curves by exponential sums:
@630 mK:
A1= 193E3 ± 26E3, Tau1 = 37.1s ± 6.3s
A2= 206E3 ± 27E3, Tau2 = 165s ± 14s
Increase size of graph remove the text?
Add error and pre factor for comparison
09-Sept-2013
F.Martin Latests results

7. Longitudinal UCN velocities
Experiment: Time Of Flight
In vacuum measurement
About 1 m flight path
Cascade Detector (detection in thin B layer)
630mK:
Velocities centered on 5m/s
Cutoff due to Al foil on detector
09-Sept-2013
F.Martin Latests results

8. Conclusion and perspectives
The new UCN source SUN2 is under test at ILL on a dedicated beam position
High UCN density measured ~ 120 UCNs/cm3
Soft UCN spectrum (horizontal velocities about 5 m/s)
Connect lifetime experiment HOPE to the source
Improve UCN extraction and cryogenics
Improve storage time by magnetic reflector
09-Sept-2013
F.Martin Latests results

9. present SUN2 collaboration
Serguei Ivanov, Michael Kreuz, Kent Leung, Florian Martin, Felix Rosenau, Martin Simson, Oliver Zimmer (ILL)
Thorsten Lauer (TU Munich, Ni/Mo coatings, UCN TOF experiments)
Mikhail Lasakov (PNPI, Be coatings)
09-Sept-2013
F.Martin Latests results

10. ANNEXES
09-Sept-2013
F.Martin Latests results

11. Tof
09-Sept-2013
F.Martin Latests results