In collaboration with the European Space Agency (ESA), the needed equipment for Single Event Events (SEE) studies using heavy ions has been built and installed on one of the beamlines in the experimental hall of Louvain-la-Neuve cyclotron. Here is a brief description of the setup and its possibilities
The CYClotron of LOuvain la NEuve (CYCLONE) is a multiparticle, variable energy, cyclotron capable of accelerating protons (up to 85 MeV), alpha particles and heavy ions. For the heavy ions, the covered energy range is between 0.6 MeV/AMU and 27.5 MeV/AMU. For these ions, the maximal energy can be determined by the formula 110 Q² / M where Q is the ion charge state, and M is the mass in Atomic Mass Units. The heavy ions are produced in a single stage (6.4 GHz) Electron Cyclotron Resonance (ECR) source. The ions are extracted at low energy ( around 10 * Q keV ), an analyzing magnet is used to select the desired M/Q ratio and then the ions are injected axially for subsequent acceleration. The use of an ECR source allows us to produce highly charged ions and ion "cocktails". These are composed of ions with the same or very close M/Q ratios. The cocktail ions are injected in the cyclotron, accelerated at the same time and extracted separately by a fine tuning of the magnetic field or a slight changing of the RF frequency. One of the main advantages of the cyclotron - ECR source combination is the fast changing of ion species. Within the same cocktail, it takes only a few minutes to change from one ion to another.
| M/Q=5 | DUT energy [MeV] | Range [µm Si] | LET [MeV/mg/cm²] |
| 40 Ar 8+ | 150 | 42 | 15.9 |
| 20 Ne 4+ | 78 | 45 | 6.2 |
| 15 N 3+ | 62 | 64 | 3.3 |
| M/Q=5.07 | DUT energy [MeV] | Range [µm Si] | LET [MeV/mg/cm²] |
| 132 Xe 26+ | 459 | 43 | 67.7 |
| M/Q=4.94 | DUT energy [MeV] | Range [µm Si] | LET [MeV/mg/cm²] |
| 84 Kr 17+ | 316 | 43 | 40.1 |
| Ion | DUT energy [MeV] | Range [µm Si] | LET [MeV/mg/cm²] |
| 13 C 4+ | 131 | 266 | 1.2 |
| 22 Ne 7+ | 235 | 199 | 3.6 |
| 40 Ar 12+ | 372 | 119 | 9.95 |
| 58 Ni 18+ | 567 | 85 | 21.3 |
| 83 Kr 25+ | 756 | 92 | 31.0 |
A highly charged Xe beam is under development
For special purpose, a low LET beam has been developed:
| Ion | DUT energy [MeV] | Range [µm Si] | LET [MeV/mg/cm²] |
| Alpha | 9.2 | 63 | 0.4 |
The beam flux is variable between a few particles / s cm² and 1·104part. / s cm². On special request, the users have the possibility to increase the flux up to 106part/s cm².
The beam flux can be modified from the user station, this is done with injection grids (for a constant attenuation factor ) or by inflector bias variations (for intermediates values).
The Homogeneity is ± 10 % on a 25 mm diameter.
The chamber has the shape of a barrel stretched vertically, its internal dimensions are 71 cm in height, 54 cm in width and 76 cm in depth. One side flange is used to support the board frame and user connectors. This flange is placed on a rail system and can be removed as far as 1 m from the chamber. In this way, the user has a lot of space for device installation etc.
The frame system consist on a X,Y,Z, Theta mechanism . We have a translation movement (with a stroke of 260 mm), which allows the irradiation from side to side of the test boards. The rotation movement allows rotation from -90° to +90°, an additional translation movement has been added to properly place the component on the rotation axis. This last one is useful when there are different device packaging or socket heights on the same board, its stroke is 20 mm upstream and 40 mm to the back. A latest vertical translation has been added, its stroke is 100 mm upward and 20 mm downward. The frame dimensions are 25 X 25 cm (compatible with BNL and the Proton Irradiation Facility -PIF- in Switzerland).
To load a JPG picture of the frame
(File size=56 K)
To load drawings of the frame without
rules (JPG format 116 K)
To load drawings of the frame with
rules (JPG format 86 K)
To load drawings of the frame
withusable area (JPG format 209 K)
An iris is placed to avoid neighboring components irradiation, its aperture is controlled by the users by means of a joystick. The aperture can be fixed between 6 and 60 mm and is stored in the device position file for each sample.
A camera is placed in the chamber for device positioning.
The standard connector flange contains:
However, user adapter plates with special feed-through configurations can easily be accommodated.
The chamber is equipped with a vacuum system fast enough to pump down in less than 10 minutes.
To load a JPG picture of the test
chamber (File size=80 K)
To control and monitor the beam parameters (flux and homogeneity) a box placed in front of the chamber contains a faraday cup, 4 scintillators and 2 Parallel Plate Avalanche Counters (PPAC). Two additional surface barrier detectors are placed in the test chamber.
The faraday cup is used during beam preparation at high intensity.
When the beam is ready, defocused and the flux lowered, we proceed to a beam uniformity measurement with a collimated surface barrier detector. This detector is placed on a X and Y movement. Scans can be done automatically by the user interface, the final profile is drawn on the user screen and the ± 10 % width is calculated. If the profile meets the user criteria a PPAC calibration is performed.
The PPAC are checked with a 1 cm² surface barrier detector. During the irradiation, the PPAC flux is integrated in order to give the delivered total fluence on the device. This detector can also be used to switch off the beam when a preset fluence is reached. The second PPAC is kept in stand by in case of failure of the first one.
The four scintillators are placed at 90 degrees to each other to measure the beam uniformity during irradiation. Different collimators are used in function of the used beam flux.
To load a JPG picture of the
scan and calibration detectors (File size=82 K)
To load a JPG picture of
the test chamber and dosimetry box (File size=86 K)
A complete user interface in C/C++ in a Windows environment has been developed. In this way, the users have access to all the beam flux control, dosimetry features, device positioning, vacuum controls and cross section versus LET via 3 screens and 10 icon tool bars. A fourth screen is reserved for CYCLONE staff.
Screens are divided by function : - BOARD-POSITION - DATA-BEAM - BEAM LINE - OPERATOR.
The first screen allows the users to store the device positions for different boards.
The second screen includes all the beam parameters ( as the ion type, flux,… ). When the users have selected a target material and ion type from a drop down list, the LET and range are automatically displayed. From there, it's also possible to tilt the device to a desired angle or to choose a LETeff and automatically do a rotation to reach it. The users have also access to the run data like delivered fluence and calculated dose. The users may enter the memory size and error number to calculate the cross section and plot it. Moreover, an input is free for a TTL signal which, if this is connected to the test system, allows an automatic cross section measurement. All run data (ion, fluence, cross section, ...) are stored in a logbook file for latter printout.
The BEAM LINE screen is used to do calibrations (scan and flux measure), to insert beam attenuation grids and pump down or vent the test chamber.
The OPERATOR screen is password protected for security reasons. This one includes access to the different detectors, detector biasing, access to all line valves, vacuum control of all the line and diffusion foil and PPAC swapping. For the most used features of the installation such as vacuum chamber, start/stop irradiation, grids, laser light, light in the chamber and defined rotation angles, the users have all the time access to a tool bar.
