RoentDek DLD40 User manual

RoentDek
HandelsGmbH
Supersonic Gas Jets
Detection Techniques
Data Acquisition Systems
Multifragment Imaging Systems
MCP Delay Line
Detector Manual
(Version 11.0.1304.1)

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D-60438 Frankfurt am Main
Germany
Web-Site:
www.roentdek.com
WEEE:
DE48573152
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All rights reserved. Technical changes may be made without prior notice. The figures are not binding.
We make no representations or warranties with respect to the accuracy or completeness of the contents of this publication.
Page 2 of 83 MCP Delay Line Detector Manual (11.0.1304.1)

Table of Contents
DETECTOR SYSTEM - COMPONENTS.......................................................................................................................5
1THE MICROCHANNEL PLATE DETECTOR WITH DELAY-LINE ANODE................................................7
1.1 GENERAL DESCRIPTION.........................................................................................................................................8
1.1.1 Position Encoding.........................................................................................................................................8
1.1.2 Timing information:.................................................................................................................................... 10
1.2 ASSEMBLY OF THE MCP-DETECTOR ...................................................................................................................11
1.2.1 List of Detector Assembly Parts..................................................................................................................11
1.2.2 Preparation.................................................................................................................................................11
1.2.3 Connecting the Wires to the Delay-line Anode...........................................................................................12
1.2.4 Assembly of the MCP-stack.........................................................................................................................14
1.2.4.1 Assembly of the MCP-stack for the DLD40, DLD80 and HEX80 ...........................................................................14
1.2.4.2 Assembly of the MCP-stack for the DLD120 and HEX120 .....................................................................................18
2MOUNTING OF THE DETECTOR AND CABLE CONNECTIONS VIA VACUUM FEEDTHROUGH....23
2.1 MOUNTING OF THE DETECTOR ON A VACUUM-FLANGE ...................................................................................... 23
2.2 CONNECTING THE SIGNAL CABLES TO A FEEDTROUGH FLANGE .........................................................................25
2.3 THE FT12TP (HEX)–FEEDTHROUGH FLANGE WITH SIGNAL DECOUPLER ..........................................................26
2.4 THE FT4(TP) FOR FT16(TP) AND DET40/75......................................................................................................29
2.5 OPERATION OF THE MCP DETECTOR WITH DELAY-LINE (OR TIMING)ANODE ......................................................30
2.5.1 Initial Startup Procedure............................................................................................................................30
2.5.2 General Operation......................................................................................................................................32
3THE FRONT-END TIMING ELECTRONICS MODULES: AMPLIFIER & CFD MODULE.......................35
3.1 SIGNAL INPUTS AND AMPLIFICATION ................................................................................................................... 36
3.2 THE DLATR BOARD............................................................................................................................................38
3.3 CFD CONTROLS AND OUTPUTS ............................................................................................................................ 38
3.4 CONNECTING AND OPERATING THE ATR19.........................................................................................................40
3.5 OPENING THE ATR19 MODULE............................................................................................................................ 41
3.6 THE ATR19-2(B)MODULE ..................................................................................................................................42
3.7 FINAL ADJUSTMENT FOR DETECTOR OPERATION .................................................................................................43
3.8 THE SPS1(B)MAINS ADAPTER.............................................................................................................................46
3.8.1 Connecting the SPS1...................................................................................................................................46
3.8.2 How to switch the AC supply voltage..........................................................................................................47
3.8.3 Output voltage adjustment.......................................................................................................................... 48
3.8.4 Maintenance and Troubleshooting .............................................................................................................48
3.8.5 Technical Specifications .............................................................................................................................49
3.9 TROUBLESHOOTING THE ATR19’S INTERNAL MAINS POWER SUPPLY ..................................................................49
4DATA ACQUISITION HARD- AND SOFTWARE..............................................................................................53
4.1 THE TIME-TO-DIGITAL-CONVERTERS (TDC) FOR PC..........................................................................................53
4.1.1 TDC8HP .....................................................................................................................................................53
4.1.2 The HM1 / HM1-B ...................................................................................................................................... 54
4.1.3 The TDC8....................................................................................................................................................55
4.2 HARD-AND SOFTWARE INSTALLATION ...............................................................................................................55
4.2.1 TDC8HP .....................................................................................................................................................55
4.2.2 HM1 / HM1-B............................................................................................................................................. 56
4.2.3 TDC8........................................................................................................................................................... 57
4.3 CONNECTING THE ATR19 OR CFD WITH THE TDC.............................................................................................57
4.3.1 TDC8HP (or TDC8) ................................................................................................................................... 58
4.3.2 HM1 / HM1-B............................................................................................................................................. 58
4.4 STARTING THE COBOLDPC 2011 R3 SOFTWARE: ................................................................................................58
4.4.1 Hardware specific commands: DAq-parameters and coordinates............................................................. 61
4.4.2 Analysis specific commands: DAn parameters and coordinates ................................................................62
4.4.3 Spectra and condition definition commands...............................................................................................65
5HIGH VOLTAGE SUPPLIES................................................................................................................................. 69
MCP Delay Line Detector Manual (11.0.1304.1) Page 3 of 83

5.1 THE HV 2/4 DUAL HIGH VOLTAGE SUPPLY MODULE........................................................................................... 69
5.2 THE BIASET3 WITH SPS2(MINI).........................................................................................................................71
5.3 BA3 BATTERY UNIT.............................................................................................................................................73
5.4 HVT AND HVT4 HIGH VOLTAGE TERMINATORS................................................................................................ 74
5.5 HVZ VOLTAGE DIVIDER UNIT ..............................................................................................................................75
APPENDIX: (MCP’S):.....................................................................................................................................................79
LIST OF FIGURES..........................................................................................................................................................81
LIST OF TABLES............................................................................................................................................................ 83
LIST OF EQUATIONS....................................................................................................................................................83
Page 4 of 83 MCP Delay Line Detector Manual (11.0.1304.1)

Detector System - Components
This manual describes all major components of the RoentDek delay-line detector system as it can be delivered for the
DLD40(EP), DLD80(75eT), HEX80/HEX75 and DLD120 and HEX120(100) detector. Even if you have not purchased
the complete system you will find valuable information in the chapters describing the different components about the link
between the components and the operation. However, you might have received only the relevant parts of this manual.
1. DLD or HEXmicrochannel plate detector with delay-line anode
0. FT12(16)TP 12-pin CF35 (and fourfold MHV) UHV-feedthrough flange(s) with signal decouplers and (optional)
flange mounting gear on DNxxxCF flange with CF35 ports (xxx = 100 – 300)
0. ATR19 fast (differential) amplifier unit with integrated constant-fraction-discriminator (default) or
FAMP8 (or similar) amplifier unit, CFD8c/7x: (or similar) constant-fraction-discriminator modules (for download)
0. TDC8HP or HM1 time to digital converter and
CoboldPC
read-out software (default) or
fADC4/8 fast ADC units (for download)
Error! Reference source not found.. HV2/4,BIASET3 or similar high voltage supply assembly and
BA3/HVT/HVZ auxiliary bias units.
Please follow the link http://www.roentdek.com/manuals for device specific manuals.
If you have received special detector components, i.e. a detector of different size or type, or other electronic modules you will
find a separate manual commenting on peculiarities of your special system. In this case the information given here is mostly
relevant for your system but you might need extra information. Please also refer to the FAQ document on the web page.
Please always check our web site for updates after you have received our products or contact RoentDek.
MCP Delay Line Detector Manual (11.0.1304.1) Page 5 of 83

Page 6 of 83 MCP Delay Line Detector Manual (11.0.1304.1)

1
The Microchannel Plate Detector with delay-line anode
The Micro-Channel Plate detector with delay-line anode is a device for single particle/photon counting, giving information on
the position of each particle/photon and its impact time with high precision. It uses an electronic read-out scheme employing
fast timing amplifiers, timing discriminators and digitizers. It operates under ultra-high vacuum and requires high voltage
supplies.
This detector system is modular and com in different sizes and versions.
Typical performance:
position resolution < 0.1mm
overall linearity 0.3mm
rate capability 1MHz
multi-hit dead time 10-20ns
Typical characteristics of MCPs (for DLD40EP, DLD75eT and HEX75 see below)
# of MCPs in stack 2
Outer Diameter: 50/86.6/127mm
Active Diameter: 45/80/120mm
Aspect Ratio L/D 60:1
Thickness 1.5mm
Pore size 25µm
Center-to-center spacing: 32µm
Bias Angle: 8° ±1°
Open Area Ratio: >50%
for DLD40EP MCP: 40mm OD (>40mm active), L/D 80:1 , 1mm thickness, 13µm pore size, bias angle: 20°, OAR > 70%
for DLD75eT MCP: 86.7mm OD (75mm active), L/D 80:1; 1mm thickness, 13µm pore size, bias angle: 19°, OAR 64%
for HEX75 MCP: 86.7mm OD (75mm active),L/D 40:1; 1mm thickness, 26µm pore size, bias angle: 20°, OAR 70%
The HEX75 uses triple MCP stacks (Z-stacks). Other detectors can also be delivered with triple MCP stacks (option …/Z)
The HEX120 can also be delivered as HEX100 with 114mm OD MCP (105mm active), 26µm pore size, bias angle: 20°, OAR
70%
Typical characteristics of the detector assembly
Height above a mounting Flange: about 100mm (adjustable)
Mounting Diameter: 94/144/196/246mm
Operating Temperature Range: -50 to 70°C
Operating Pressure: < 2 x 10-6mbar
Baking Temperature: 150°C Maximum
Electron Gain @ 2400Volts*: 107Minimum
If you have chosen a detector set with central hole, its size in the MCP is usually 6.4mm and the minimum active diameter
9mm.
If you have chosen a different custom detector type, e.g. DLD25, DLD80x100, DLD100, DLD150, or HEX40 please refer
to the separate instructions.
*For DLD40EP, DLD75eT or /Z options: about 300V higher voltages may be applied.
MCP Delay Line Detector Manual (11.0.1304.1) Page 7 of 83

1.1 General Description
The RoentDek MCP detector with delay-line anode is a high resolution 2D-imaging and timing device for charged particle
or photon detection at high rates with limited multi-hit capability. The linear active diameter is at least 40mm for the detectors
with the DL40 anode (e.g. DLD40 and DLD40EP), 75mm for the DL80 anode (e.g. DLD80 and DLD75eT), and about
120mm for the DLD120. The RoentDek Hexanode has a third delay-line layer that gives redundant detection opportunities
either to improve the multi-hit performance, linearity or to allow the use of a MCP setup with central hole and minimized blind
detection area. In its usual version (HEX80) it has about 75mm redundant detection area (HEX120: 100mm redundant, up to
115mm linear with at least two layers, total up to 120mm, HEX100: 100mm redundant detection area, HEX40about 40mm
redundant detection area)*. For detectors with central hole (e.g. HEX40/o and HEX80/o) the descriptions in this manual are
also relevant unless otherwise stated. A DLD150 version is available on demand with 150mm active detection diameter.
The detector consists of a pair of selected MCPs in chevron configuration or of a triple stack (Z-stack) and a helical wire delay-
line anode for two-dimensional position readout. The MCPs are either supported by a pair of partially metalized ceramic rings
(1.5/2mm thick, 65/105mm outer diameter for DLD40/DLD80 and HEX80 with metal contacts on the ceramic rings are
suitable for soldering, clamping or spot welding) or the MCP stack is mounted between a metal front ring and a (usually square-
shaped) rear side holder plate, e.g. for the DLD120 and HEX120(100) or custom MCP stack designs.
Operation requires two DC voltages for a (resistance matched) MCP stack on front and back contacts and three voltages for
the anode’s support plate (“holder”) and the anode wire array. All voltages can be supplied by separate HV-supplies or voltage
dividers. The baking limit is specified as 150°C for the detectors and for optionally provided in-vacuum cables and feedthroughs.
The wire array consists of two or three helical wire propagation double (delay) lines. For each dimension a differential wire pair
is formed by a collection (signal) wire and a reference wire. A potential difference of 20V to 50V between signal and reference
wire ensures that the electron cloud emerging from the MCP is mainly collected on the signal wires, shared between the wire
layers for different position encoding directions. The anode holder has to be biased with an intermediate potential with respect
to the anode wires and the MCP back potential to ensure proper charge cloud propagation and spatial broadening in the drift
zone between MCP and anode wires. The optimal voltage depends on the distance between the MCP holder plate and the
anode wires.
Typically the wires should have about 300V more positive potential than MCP back side and the holder about +100V with
respect to the MCP back potential.
Avoid penetration of strong external electrical and magnetic fields into the electron cloud drift region (between MCP and wire
anode). Electrical fringing fields can produce image distortions, magnetic fields (> 50Gauss) disturb the proper charge cloud
broadening and will lead to malfunction of the anode.
1.1.1
Position Encoding
The position of the detected particle/photon is encoded by the signal arrival time difference at both ends of each parallel-pair
delay-line, for each layer independently. While the signal speed along the delay line is close to speed of light, one can define a
perpendicular signal speed v⊥given by the pitch of one wire loop (typically 1mm) and the time, which a signal needs to propagate
though this loop. This defines the single pitch propagation time per 1mm which is equal to 1/v⊥(in units mm/ns).
The corresponding ends of the delay-lines for each dimension are located on the opposite corners of the wire array terminals
on the rear side. The electrical resistance of each wire is between 5 and 100Ωend-to-end, depending on the size of the delay-
line and the wire type used. Corresponding ends of wires can such be identified. The four (or six) terminal pairs have to be
connected to vacuum feedthroughs by a twisted-pair cable configuration (both cables of a pair must have equal lengths, within
5mm). From the feedthroughs the signals must be transmitted (after DC-decoupling) to a differential amplifier or signal
transformer with equally adequate transmission cables.
The difference between the signal arrival times at the adjacent ends of each delay-line is proportional to the position on the
MCP in the respective dimension. The sum of these arrival times is fairly constant with few ns for each event (see below). The
time sequence of the signals can be measured by time-to-amplitude converters (TAC) or an n-fold time-to-digital converter
(TDC), n is at least 4 or up to 7 (Hexanode with separate timing channel). As time reference the signal on the MCP back or
front side can be used for correlating each particle to others or to an external trigger (TOF-measurement).
For the DLD detectors, the digital encoding for obtaining a 2d digital image (X/Y) is
*In the following we will refer to those detectors using the same anode only by nominating one detector version, e.g. for
DLD40 and DLS40eT as DLD40 unless otherwise noted. Additional remarks, if any, will refer to the different MCP types.
Page 8 of 83 MCP Delay Line Detector Manual (11.0.1304.1)

X = x1 – x2 + Oxand Y = y1 - y2 + OyEquation 1.1
with x1, x2, y1 and y2 denominating the time for each signal, Oxand Oyare arbitrary offsets.
The fast timing signal picked up from an MCP contact or, in the case of a pulsed particle/photon source, a “machine trigger”
signal can serve as time reference. The single pitch propagation time (for 1mm) on the delay line is about 0.75ns for DLD40,
1ns for DLD80 and 1.24ns for DLD120. Thus the correspondence between 1mm position distance and relative time delay in
the 2d image is twice this value: about 1.5ns, 2ns or 2.5ns, respectively. Note that these numbers are only accurate within 5%
and are slightly different for each dimension. In order to calculate the position in mm from the digital X and Y values you have
to take into account the bin width of your TDC and the single pitch propagation time for the respective layer.
Figure 1.1: Operation principle of the delay-line-anode,
left picture from: Sobottka and Williams IEEE TS-35 (1988) 348
The Hexanode has an additional layer and gives over-determined (redundant) position information: It is possible calculating
the two-dimensional particle position of signals from of any two of the tree layers. The signals from the third layer serve as a
redundant source of information for cases when signals are “lost” due to electronic dead-time (multiple hit events), non-
continuous winding schemes (anode with central holes) or non-perfect electronic threshold conditions/damping on special
very large delay-line anodes. With the Hexanode it is also possible to control their delay-lines’ intrinsic resolution and linearity,
improving the overall imaging performance. The Hexanode’s coordinate frame u, v, w can be transformed into a Cartesian
coordinate system by the following equations using only two of the hexagonal coordinates respectively, if the connection
scheme in the next section is chosen:
X
uv
=
Oxu+
Yuv =
( )
y O
vu +
−2
3
1
Xuw = Xuv
Yuw =
( )
y Ouw +−2
3
1
Xvw =
( )
x O++ wv
Yvw =
( )
yOv
w+−
3
1
Equation 1.2
Oxand Oyare arbitrary offsets. The position in a hexagonal coordinate frame is coded by the arriving time differences from
signals in opposite corners of the anode as in case of the DLD.
u = (x1 – x2) * d1
v = (y1 – y2) * d2
w = (z1 – z2) * d3 + o
Equation 1.3
If 1/viis the single pitch propagation time for a delay line layer i (viis slightly different for each layer) then diis given by
MCP Delay Line Detector Manual (11.0.1304.1) Page 9 of 83

di= ½ vi* ∆t Equation 1.4
dimust be precisely known to make the images obtained via different layer combination coherent. o is an offset value that shall
unify the “time difference zero” of all three layers, i.e. it must be chosen so that geometrically the position lines for calculated
u, v, w have a common crossing point, e.g. w must be zero when u and v are zero.
For the HEX80 the single pitch delay is about 1.4ns. The exact values u, v, w, o differs from anode to anode. There relative
values must be precisely determined which can be done by a self-calibration routine (for details please contact RoentDek).
o is also a function of connection cable lengths and cable lengths all the way to the TDC/TAC inputs (and internal offsets
therein) and must therefore be recalibrated whenever these parameters have changed. The single pitch delay for the HEX120
is about 1.75ns which corresponds to a pitch of 1mm or 1.5mm, depending on the anode version which you have received
(default: 1.5mm).
For detectors with central hole, the gaps in the wiring have to be taken into account. Please contact RoentDek for the
program codes appropriate for your detector.
The linearity deviations in each delay-line layer should be calibrated to achieve optimal results. Please contact RoentDek for an
auto-linearization routine and advanced position codes.
The X and Y positions can be calculated from any combination of the Equation 1.2. If for a given event more signals than from
the minimum of two layers are available, it is recommended to choose signals from those two layers where the positions are
most distant from the respective delay line ends (or gaps).
1.1.2
Timing information:
In order to determine the time difference between an outer time marker and the particle impact, the signal at the MCP contact
can be used. But it is also possible to deduce the particle impact time from the delay-line signals:
If the MCP signal is used as the time-zero, the “time sum” values
sumx = x1 + x2
sumy = y1 + y2
sumz = z1 + z2 (only available for Hexanodes)
Equation 1.5
are constant within the time resolution (less than one ns) but have a slight “position walk” which can be determined by plotting
sum vs. difference (i.e. position). Thus it is also possible to deduce the particle impact time from these time sum values alone.
Even if the particle timing is not of interest, the time sum measurement can be used to verify a proper detector function.
Figure 1.2: Typical imaging/timing performance of a DLD40 detector. The detector (shaded by a mask) was
irradiated with
α
-particles. Similar or better results can be achieved with adequate read-out electronics. Temporal
resolution is significantly better than the local time sum width (see right picture) which indicates an upper limit.
Page 10 of 83 MCP Delay Line Detector Manual (11.0.1304.1)