-
Notifications
You must be signed in to change notification settings - Fork 5
/
Copy pathsinglephasedet.tex
134 lines (94 loc) · 11.3 KB
/
singlephasedet.tex
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
\label{singlephasedet}
\subsection{DUNE detector plans}
The far detector for the DUNE collaboration will be a series of four liquid argon TPCs, each in a cryostat that holds a fiducial/active/total LAr mass of 10.0/13.3/17.1~kt. The TPCs will be instrumented with a photon detection system. It is planned that the first 10~kt detector will be ready for installation in the 2022 timeframe.
The design for the first 10~kt detector is a submerged wire plane-based TPC with electronic readout also in the liquid argon. Designs of this style are referred to as single-phase detectors as the charge generation, drift, and detection all occurs in the liquid argon phase. This style TPC features no charge amplification before collection, thereby making a very precise charge measurement possible.
To achieve DUNE's goals, a detector is needed that is much larger than ICARUS, the largest LAr TPC detector built to date. The former LBNE developed a scalable far detector design shown in Fig.~\ref{fig:fardet-overview} that would scale-up LAr TPC technology by roughly a factor of 40 compared to the ICARUS T600 detector. To achieve this scale-up, a number of novel design elements need to be employed. A membrane cryostat typical for the liquefied natural gas industry will be used instead of a conventional evacuated cryostat. The wire planes or APAs will be factory-built as planar modules that are then installed into the cryostat. The modular nature of the APAs allow the size of the detector to be scaled up to at least 40~kt fiducial mass. Both the analog and digital electronics will be mounted on the wire planes inside the cryostat in order to reduce the electronic noise, to avoid transporting analog signals large distances, and to reduce the number of cables that penetrate the cryostat.
The scintillation photon detectors will employ light collection paddles to reduce the required photo-cathode area and thereby cost. Designs being considered are also more compact than the photomuliplier tubes solution used elsewhere.
Many of the aspects of the design are being tested in a small scale prototype at Fermilab but given the very large scale of the detector elements a full-scale test is critical.
Since the recent formation of the new DUNE collaboration a combined detector design team is emerging.
Ideas from this new collaboration have the potential to modify the detector design for the additional three far detector modules
which are foreseen for DUNE.
The detector design described here is the LBNE detector design chosen by the DUNE collaboration as the reference design for the first 10~kt
detector module and also adopted as the basis for the DUNE-PT.
\begin{figure}[!htb]
\centering
\begin{minipage}[b]{1.0\textwidth}
\begin{center}
\includegraphics[width=.75\textwidth]{figures/fardet-3D.png}
%\includegraphics[width=0.7\textwidth]{EndView-sketch.png}
\end{center}
\end{minipage}
\caption{\small 3D model of the design for the first DUNE single-phase detector. Shown is a 5~kt fiducial volume detector which would need to be lengthened for the 10~kt design. The present DUNE plan calls for the construction of four 10~kt detectors. }
\label{fig:fardet-overview}
\end{figure}
The engineering goals of the single-phase APA/CPA detector test can be broken into five broad categories:
\begin{enumerate}
\item TPC performance, mechanical and electrical verification,
\item photon detection light yield verification,
\item calibration strategy verification,
\item argon contamination mitigation verification,
\item production and installation procedure verification
\end{enumerate}
The goals related to mechanical testing are to test the integrity of the detector. In the current design, each APA measures 2.3 m by 6.0 m and includes 2560 wires and associated readout channels. Given the complexity of these assemblies, a test where the detector can be cooled down and tested under operating conditions is highly advisable prior to mass production. The mechanical support of the APAs can be tested to verify that the mechanical design is reliable and will accommodate any necessary motion between the large wire planes. The impact of vibration isolation between the cryostat roof and the detector can also be tested. Finally, an improvement over existing cryostat designs is the possibility to move the pumps external to the main cryostat. This will reduce any mechanical coupling to the detector and also greatly improve both reliability and ease of repair.
The electrical testing goals are to insure that the high voltage design is robust and that the required low electronic noise level can be achieved. As the detector scale increases so does the capacitance and the stored energy in the device. The design of the field cage and high voltage cathode planes needs to be such that HV discharge is unlikely and that if the event occurs no damage to the detector or cryostat results. The grounding and shielding of large detectors is also critical for low noise operation. By testing the full scale elements one insures that the grounding plan is fully developed and effective. Large scale tests of the resulting design will verify the electrical model of the detector.
Research at Fermilab utilizing the Materials Test Stand~\cite{mat-test-stand} has shown that electronegative contamination to the ultra-pure argon from all materials tested is negligible if the material is immersed in the liquid argon. This implies that the dominant source of contamination originates from the gas ullage region and the room temperature connections to the detector. Careful design of the ullage region to insure that all surfaces and feedthroughs are cold is expected to greatly reduce the sources of contamination over what exists in present detectors.
\subsection{DUNE-PT}
%\subsubsection{Overview of the CERN Single-Phase test Detector}
This section presents the design details of a single-phase prototype detector based on the design by the former LBNE collaboration \cite{LBNE-design}.
The DUNE detector design is modular and the DUNE-PT will be constructed from modular components of exactly the same design.
\begin{figure}[htb]
\centering
\begin{minipage}[b]{1.0\textwidth}
\begin{center}
\includegraphics[width=0.40\textwidth]{figures/CERN_single_TPC}
\includegraphics[width=.59\textwidth]{figures/TPC-3D-section.jpg}
\end{center}
\end{minipage}
\caption{\small 3D model of the CERN single-phase detector TPC (left) and inserted in the cryostat (right).}
\label{fig:CERNdet-overview}
\end{figure}
The TPC consists of alternating anode plane assemblies (APAs) and cathode plane assemblies (CPAs), with field-cage panels enclosing the four open sides between the anode and cathode planes. Fig.~\ref{fig:CERNdet-overview} shows a sectioned view for the planned TPC
by itself and inside the cryostat at CERN. A 500 V/cm uniform electric field is created in the volume between the anode and cathode planes. A charged particle traversing this volume leaves a trail of ionization. The electrons drift toward the anode plane, which is constructed from multiple layers of sense wires, inducing electric current signals in the front-end electronic circuits connected to the wires.
The TPC will be assembled from elements that are of the same size and materials as those planned for the first DUNE far detector module.
The overall size of the TPC has been determined based on the desired particle containment in order to address the required physics measurements (see Section \ref{detbeamtest}). The TPC will have an active volume that is 3 APAs long and consists of two drift volumes with a drift length of 3.6~m each (see Fig.~\ref{fig:CERNdet-overview}).
The APAs have an active (total) area measuring 2.29 m (2.32 m) wide and 5.9 m (6.2 m) high. The combination of the three APAs determines the overall TPC length to be 7.0~m. There will be a CPA in the center between the two rows of APAs.
The overall width of the TPC will be determined by the 7.4~m combination of the drift distances and the total thicknesses of the two APA planes and the CPAs.
The overall height of the TPC is determined by the height of the APA which is 6.2~m. The TPC dimensions are summarized in
Table~\ref{table:TPC-dim}.
%
The minimum internal size of the cryostat is also indicated in Table \ref{table:TPC-dim} and was determined by adding the necessary mechanical and electrical clearances to the computed size of the TPC.
\begin{table}[h]
\centering
\begin{tabular}{|c|c|}
\hline
\textbf{ Component } & dimensions [m] \\ \hline \hline
APA (active) & $2.29 (wide) \times 5.9 (high)$ \\ \hline
APA (external) & $2.32 (wide) \times 6.2 (high)$ \\ \hline
TPC (active) & $7.0 (long) \times 7.2 (wide) \times 5.9 (high)$ \\ \hline
TPC (external) & $7.3 (long) \times 7.4 (wide) \times 6.2 (high)$ \\ \hline
cryostat (internal) & $8.9 (long) \times 7.8 (wide) \times 8.1 (high)$ \\ \hline
\end{tabular}
\caption{Dimensions of DUNE-PT.}
\label{table:TPC-dim}
\end{table}
Along with the APAs and CPAs, the TPC will include a field cage that surrounds the entire assembly to ensure a uniform drift field in the TPC's active volume. -
%This is a series of fiberglass I-beams for the structural elements. These I-beams will be tiled with large copper sided FR4 panels to create the field cage. Each panel will be connected with a series of resistors. The field cage will also be connected to the CPAs through a capacitor assembly.
All of this will be supported by rows of I-beams supported from a mechanical structure above the cryostat. The hangers for these I-beams will pass through the insulated top cap. There will be a series of feedthrough flanges in the top cap of the cryostat to bring in and take out services for the TPC. One HV feed-through is foreseen for the CPA row and one signal feed-through for each of the APAs.
The design also foresees the option to have the two APA rows mounted at 2.5~m from the central CPA each.
A reduced drift distance between the APA and CPA represents a deviation from the DUNE far detector design but is potentially very
useful in order to lessen the impact of space charge effects.
Due to the operation of DUNE-PT on the surface, space charge
effects (discussed in Section~\ref{calibration}) are expected to be larger than for underground operation at SURF.
We foresee to calibrate out any space charge effects for a 3.6~m drift distance using laser beam calibration and cosmics.
At the same time we maintain the possibility for a second test with reduced drift length if the uncertainties associated
with our calibration limit the precision of measurements.
The cryostat would have to be emptied and the planes shifted to the 2.5~m drift distance.
%The plan is to have the CPA located in the center of the cryostat with APAs on each side near the walls of the cryostat membrane. The above dimensions preserve the ability to reverse the order of the TPC rows by placing the CPA next to the wall of the cryostat and the APAs in the center. However, this can only be done with the shorter 2.5m drift distance. This reversed configuration at the 3.6m drift distance would place the CPAs too close to the membrane and risk high voltage discharge and and thereby possible damage to the membrane.
% File from Bo Yu on the TPC component design
\input{APA-CP-FieldCage}
\subsubsection{Photon detection system}
\input{photondetector}
\subsubsection{TPC and PDS readout}
\input{readout}
\subsubsection{DAQ, slow control and monitoring}
\input{daq}