Brookhaven National Laboratory Tandem Van de Graaff

The Tandem Van de Graaff is the Brookhaven accelerator most of the published planetary single event effect results were taken on. Its distinguishing property for a test planner is that ion energy is tunable at the machine rather than by putting a degrader in the beam, so there is no straggling in the energy distribution reaching the part, and a single event effects campaign can be turned around in a week [2].

Exposures are run in vacuum, and the energies are the lowest of the four accelerators on the radiation testing page: ranges in silicon of 30 to 200 micrometers, so parts are delidded and flip chips thinned, or at the high-LET tune not tested at all [1].

Two other Brookhaven beams are not this facility. The NASA Space Radiation Laboratory runs at energies whose ranges in silicon allow a whole circuit card assembly to be irradiated without delidding; its envelope, its spilled beam structure and the error that structure introduces are recorded on the radiation testing page. The Alternating Gradient Synchrotron was used to deliver 10 GeV per nucleon gold ions at 12 MeV-cm2/mg linear energy transfer at normal incidence, at a range far exceeding that of 200 MeV proton recoils, which was sufficient to latch up any device with a measurable cross section below that LET [6].

Laboratory data

Parameter	Value
Operator	Brookhaven National Laboratory [2]
Location	Upton, New York, United States
Commissioned	Not published
Type	Tandem electrostatic accelerator, heavy ion single event effects
Floor area	Not published
Capabilities	Heavy ion beam line
Simulant or terrain	Not applicable
Instrumentation	Not published
Ground truth	Not published. Test methods follow ASTM F1192 or JEDEC JESD57 [4][5]
Fidelity limits	Monoenergetic single-species beam; 30 to 200 micrometer range in silicon [1]
Access	User facility. One week campaign turnaround achievable [2]
Cited by	radiation testing, sensors and IMUs

No operator-written facility description is held. The envelope below comes from two users’ facility comparisons and from the ion, energy and range figures recorded in the campaigns themselves [1][2][3].

Capabilities

Heavy ion beam line

Parameter	Value
Working volume	Vacuum chamber; dimensions not published [4]
Test article limits	Ceramic cover removed; flip chip thinned, or not tested at the high LET tune [1]
Vacuum	Yes. Heavy ion exposures are run in vacuum [4]
Temperature	Set by the user. Campaigns here report room temperature to 90 C [3]
Illumination	Not applicable
Slope	Not applicable
Gravity offload	Not applicable
Instrumentation	Supplied by the user

Two tunes. The low-LET tune covers 1 to 6 MeV-cm2/mg at 85 to 200 micrometers of range in silicon, with the ceramic cover removed, flip chips thinned, and no heat spreader or heat sink [1]. The high-LET tune covers 6 to 85 MeV-cm2/mg at 30 to 85 micrometers, and flip-chip parts should not be tested on it at all.

The ranges the campaign records give are consistent with that: bromine-81 at 287 MeV reaches 36 micrometers in silicon at LET 37.5 MeV-cm2/mg at normal incidence, and silicon-28 at 187 MeV reaches 74 micrometers at LET 7.8 [3].

Because ion energy is tunable at the machine, no degrader is needed to reach an intermediate energy, and the beam therefore arrives without the energy spread a degrader introduces [2]. That is what makes a one week turnaround possible.

What it does not reproduce

The spectrum. Monoenergetic, single-species, as at every accelerator here. See the radiation testing page.

Penetration. The shortest ranges of the four facilities, 30 micrometers at the high-LET tune, so every part is opened and many are thinned [1]. A result taken here is a result on a modified part.

A stated envelope. Nothing held is written by the operator. The two tune rows above come from a JPL test-engineering guideline whose author states in its own foreword that the facility table was already out of date at publication [1].

Campaigns run there

MEMS accelerometer latchup against temperature, reported 2018. Two Colibrys parts were exposed under bromine-81 and silicon-28 [3]. The SF1600S showed a non-destructive latchup threshold between LET 7.88 and 11.44 MeV-cm2/mg above 70 C at maximum recommended bias, and the MS1002A between 11.44 and 19.71 above 70 C. The temperature dependence is the result worth carrying: on the MS1002A the latchup cross section at LET 37.5 and 1e7 ions/cm2 was 6.1e-6 cm2 at 75 C against 1.5e-6 cm2 at room temperature, a factor of four [3]. A latchup screen run at ambient understates the flight case by that factor for this part.

JPL compendia heavy ion exposures, 2007 to 2012. The vacuum heavy ion half of both JPL compendia was run here, with the in-air and longer-range work at Texas A&M [4][5]. Entries taken in this configuration include the Elpida EDS5104ABTA-75 512 Mbit SDRAM, upsetting above LET 2.7 MeV-cm2/mg, with a recoverable mode-register functional interrupt above 3.8 and a run of over a thousand consecutive errors above 5.4, the latter clearing on rewrite or power cycle [4]. The same part family in the later compendium upset and suffered functional interrupts below LET 2 at about 2e-9 cm2 per bit [5]. The sample size and method caveats that apply to every compendium entry are on the Texas A&M page.