CATRiNA

CATRiNA at Gamma Station beamline

Introduction

The Compound Array for Transfer Reactions in Nuclear Astrophysics (CATRiNA) is a neutron detector array located at Florida State University. CATRiNA is composed of 32 deuterated-benzene (${\textrm {C}}_{6}{\textrm {D}}_{6}$) liquid scintillators. The array consists of 16 "small" detectors each contained in a 2" x 2" (diameter x thickness) aluminum cell and 16 "large" detectors that are each contained in 4" x 2" aluminum cells. Due to the anisotropic light-output spectrum of of neutron-deuterium scattering, the light-output can be converted to the neutron energy without time-of-flight information in a process known as spectrum unfolding . Please refer [| here] for setting up the HV source for CATRiNA.

Light-Output Response

From page 570-571 of Radiation Detection and Measurement by Knoll, the recoil neutron energy is given as a function of the target recoil angle in the lab frame $\theta$, incident neutron energy $E_{n}$, and nucleon number of target nucleus $A$

$E_{recoil}={\frac {4A}{(1+A)^{2}}}cos^{2}\theta E_{n}$

For maximum energy transfer, $\theta =0$, and

$E_{recoil}={\frac {4A}{(1+A)^{2}}}E_{n}$

For deuterium, $A=2$ which implies a maximum deposited neutron energy of $E_{recoil}/E_{n}={\frac {8}{9}}$.

From previous work, the light-output response of a given CATRiNA detector can be parameterized as a function of incident neutron energy and experimentally-extracted parameters:

$LO=aE_{dep}-b(1-e^{-cE_{dep}})$

The light output parameters are given by the following table

Size	a	b	c
2" x 2"	0.6193	2.036	0.2592
4" x 2"	0.6109	1.946	0.2625

PMT Bias

The CATRiNA Photo-Multiplier Tubes (PMTs) require bias to function. The PMT channel number will be drawn in black ink on the PVC pipe covering the detector. Below is a table of optimized biases for the R7724 (2" x 2") PMTs:

PMT Channel	Bias (V)
0	-1225
1	-1225
2	-1225
3	-1225
4	-1225
5	-1275
6	-1400
7	-1400
8	-1200
9	-1400
10	-1250
11	-1225
12	-1325
13	-1300
14	-1375
15	-1300

The 9821B (4" x 2") PMTs:

PMT Channel	Bias (V)
0	-1725
1	-1700
2	-1675
3	-1800
4	-1700
5	-1750
6	-1650
7	-1725
8	-1750
9	-1725
10	-1725
11	-1800
12	-1700
13	-1725
14	-1885
15	-1735

Digitizer setup for coincident with RF

CATRiNA cable connection

Digitizer 1 is the master, and received the RF-coin signal. Digitizer 2 and 3 are the slaves, connected to the neutron detectors

The TRG-OUT of digi-2 and -3 will be "on" when ever any channel is fired. To do so, the Local Shaped Trigs [G] must be OR.

also, the TRG-OUT Mode is Trigger (Mask) and the TRG-OUT Mask buttons are green for all channels.

Time sync

Digitizer 1 is SW controll and internal clock. The TRG-OUT mode is "RUN".

Digitizer 2 and 3 are S-IN and external clock.

Contact

Sergio Almaraz-Calderon mailto:salmarazcalderon@fsu.edu