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A 2nd-generation gravitational neutron spectrometer

The GRANIT project consists of designing and building a second-generation gravitational neutron spectrometer with ultra-high resolution. Its key property is the storage of UCN in a selected gravitationally bound state for extended period of time using a closed specula trap. The high quality of mirrors needed for the trap is at the edge of modern technology.

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Characteristics

Characteristics

reactor hall level C, cold guide H172

13.6 m downstream the vertical liquid-deuterium neutron cold source

Monochromator

graphite crystals intercalated with potassium

8.9 A monochromatic neutrons reflected towards guide H172A

Ultra Cold Neutron (UCN) source

Small size 4He source

5 liters

Environment setup

Anti-vibration and levelling systems


Clean-room class 1

at position of the GRANIT optical elements

Optics

transport mirror

25 x 30 cm2

(gravitational quantum states in flow-through mode)

 

specular trap

30 x 30 cm2 with vertical walls of ~ 500 µm

(gravitational quantum states in storage mode)

Detectors

nuclear-track position-sensitive UCN detectors

spatial resolution ~1 µm

low-background 3He UCN counters

background ~10-4 s-1

one- and two-dimensional UCN detectors

spatial resolution of ~100 µm

(to be developed)


 

 

 

The housing of GRANIT as view from top of the neutron guides. (©2009, Ecliptique - Laurent Thion)