Voyager 1 Recovery From FDS Anomaly
(last update 9/7/2024)

Excel file, last updated May 29, 2024, containing pha, rate and mrt header information from recent daily and weekly files.


Voyager 1 temperature plot from Stu

Voyager_1_Temperatures_2024-2024-07-17

Information on Engineering Values

October 2023 to September 2024 Raw DN Values

May to September 2024 DN Values

V1_Raw_MRT_Engineering_2023-2024 V1_Raw_MRT_Engineering_May2024

May to September 2024 FDS EU values (usually 0-3V)

May to September 2024 Real values (plot of V2 real values)

V1_EU_MRT_Engineering_May2024 V1_Meas_MRT_Engineering_May2024


On Jun 10, 2024, at 20:01, Douglas C. Hamilton wrote:
Tom et al.,

I agree with your conclusion, Tom, that we should stand pat for now.

I have been thinking about how to recover some composition information from the low energy end of LEPT. Since D2 is off, we won't have 2-D information. There are four rates that in theory could be useful:

1. Ch 39 E0A (E0B) (E2) nominally 0.075-0.150 MeV/nuc alphas
2. Ch 38 E0B (E0D) (E2) nominally 0.047-0.125 MeV/nuc medium nuclei

Since the E0 singles rate appears to be well behaved after FDS recovery, I thought this might be the best chance. However, my first attempt to examine Ch39 and Ch38 with VMIDL, shows Ch39 dropping after the anomaly to Ch38 levels before the problem and Ch 38 disappearing as if there had been a large gain loss in D0 such that the alpha pulses fell below E0A and medium nuclei fell below E0B and are now being counting in Ch39.

E1 singles show a noisy detector ~40,000 c/s. As far as I know, E1 sums counts from D1a and D1b, but I could be wrong. There are two singles rates from separate fast electronics connected to D1a only.

3. D1F1 (Ch46) nominally 0.15-1.1 MeV/nuc alphas
4. D1F2 (Ch47) nominally 0.13-10 MeV/nuc medium nuclei

These two rates are consistent before and after the FDS anomaly. D1F2 counts at a low rate of ~5 x 10^-4. D1F1 is a bit flakey with two different values: mostly ~2 x 10^-3 but with a second more noisy group of values ~2 x 10^-2. That behavior persists after recovery.

Since D1F1 and D1F2 are consistent across the anomaly, one might conclude that D1b is the noisy detector and turning it off could be of some benefit. However, since D1F1 and D1F2 are already "nominal" after recovery, it's not clear what turning off D1b would accomplish. Also the "bad behavior" of D1F1 may imply it's not useful anyway.

More study and comparison with V2 (only for D1F1 and D1F2 since D0 is off on V2) are needed.

Doug

v1_rate1317_2022-24 v1_rate4647_2022-24 v1_rate3839_2022-24 v2_rate1317_2022-24 v2_rate4647_2022-24 v2_rate3839_2022-24

NOTE: Many of the LECP rates typically have three readouts per 192 sec step. Some of these individual readouts are zero in the data at the start of recovery
These zeroes are not used when calculating the 192 sec singles rates averages plotted below. Step? means the step from the mrt header is unknown

E0 v1_2023-2024_E0 E0 v1_2023-2024_E0 E0 v1_2023-2024_E0 E0 v1_2023-2024_E0 E0 v1_2023-2024_E0 E0 v1_2023-2024_E0 AR v1_2023-2024_AR AL v1_2023-2024_AL E0 v1_2023-2024_ALAR E0 v1_2023-2024_CH31
PL01 v1_2023-2024_PL01 PL06 v1_2023-2024_PL06 Eb01 v1_2023-2024_Eb01 Ebp01 v1_2023-2024_Ebp01 Eb02 v1_2023-2024_Eb02 Ebp02 v1_2023-2024_Ebp02

V1_MRT_Status_Words_Nov23 V1_MRT_Status_Words_2023-2024

Much of the spread in the CH31 D4D3 matrix comes from periods with low CH31 rates.

v1_d4d3_matrix_2023-2024 v1_d4d3_matrix_ch31_lt_15_2023-2024 v1_d4d3_matrix_ch31_ge_17_2023-2024